Thomas Betts Fan UDAP User Manual
Series Fan-Type  
Unit Heaters  
C E R T I F I E D  
Installation/Operation FORM RZ-NA I-UDA  
APPLIES TO:  
Models UDAP and UDAS  
Table of Contents  
Page  
FOR YOUR SAFETY  
What to do if you smell gas:  
• Do not try to light any appliance.  
• Do not touch any electrical switch; do not use any phone in  
your building.  
• Immediately call your gas supplier from a neighbor's  
phone. Follow the gas supplier's instructions.  
• If you cannot reach your gas supplier, call your fire  
department.  
Warnings ........................................ 1  
Installation/Operation .............. 2-25  
Check/Test/Startup ................. 26-28  
Maintenance/Service .............. 28-36  
Index (by page)  
Burner ................................................... 16, 29  
Burner Orifice ............................................ 30  
Burner Removal ........................................... 29  
California Warning Label .............................. 3  
Clearances .................................................... 7  
Installation Codes ......................................... 2  
Confined Space (UDAP) ............................... 8  
Dimensions ................................................ 4-5  
Disconnect, Built-in (UDAS) ................16, 34  
Door Switch (UDAS) ............................19, 33  
Downturn Nozzle (Option) ............................ 4  
Electrical Connections ............................... 16  
Fan ............................................................... 32  
Fan Motor...............................................22, 32  
Flame Rollout Switch ......................... 18, 34  
Gas Piping and Pressures ........................... 12  
Gas Valve ...............................................22, 33  
General .......................................................... 2  
Hanging the Heater ...................................... 10  
Hazard Intensity Levels ............................... 2  
Heat Exchanger Maintenance ...................... 29  
HighAltitude ............................................ 6, 14  
Ignition System ...................................... 19, 31  
Limit Control ......................................... 18, 33  
Location (Heater) ........................................... 9  
Maintenance Schedule ............................... 28  
Pressure Switch (Combustion Air) ....... 17, 33  
Replacement Parts ................ See Form P-UD  
Sound Data ................................................... 6  
Startup .......................................................... 26  
Suspending Heater ....................................... 4  
Technical Data ............................................... 6  
Thermostat (Option) .................................. 17  
Throw (Heater) .............................................. 9  
Transformer .................................................. 33  
Troubleshooting ................................... 34-36  
Uncrating and Preparation ........................... 3  
Valve Outlet Pressure ................................... 14  
Vent System ............................................... 34  
Venter Motor ............................................... 32  
Venting Model UDAP ........ Use Form I-V-PV  
Venting Model UDAP-CV Use Form I-V-CV  
Venting Model UDAS ......... Use Form I-V-SC  
Warranty ......................................................... 3  
Wiring Diagrams .................................... 23-25  
FOR YOUR SAFETY  
Do not store or use gasoline or other flammable vapors and  
liquids in the vicinity of this or any other appliance.  
WARNING: Improper installation, adjustment, alteration,  
service, or maintenance can cause property damage, injury,  
or death. Read the installation, operation, and maintenance  
instructions thoroughly before installing or servicing this  
equipment.  
WARNING: Gas-fired appliances are not designed for use in  
hazardous atmospheres containing flammable vapors or  
combustible dust, in atmospheres containing chlorinated or  
halogenated hydrocarbons, or in applications with airborne  
silicone substances. See Hazard Levels, page 2.  
WARNING: Should overheating occur, or the gas supply fail to  
shut off, shut off the manual gas valve to the appliance before  
shutting off the electrical supply.  
WARNING: Do not use this appliance if any part has been under  
water. Immediately call a qualified service technician to inspect  
the appliance and replace any gas control that has been under  
water.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 1  
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Installations in aircraft hangars should be in accordance withANSI/NFPANo. 409  
(latest edition), Standard for Aircraft Hangars; in public garages in accordance  
with ANSI/NFPA No. 88A (latest edition), Standard for Parking Structures; and  
for repair garages in accordance with ANSI/NFPA No. 88B (latest edition), Stan-  
dard for Repair Garages. In Canada, installations in aircraft hangars should be in  
accordance with the requirements of the enforcing authorities, and in public ga-  
rages in accordance with CAN/CGA B149 codes.  
Special Installations  
(Aircraft Hangars/  
Repair Garages/  
Parking Garages)  
If the heater is being installed in the state of California, the installer MUST attach  
a warning label on the outside of the access door. The California Warning label is  
shipped in the owner’s envelope along with this manual, the warranty form, and  
any other paperwork that applies.  
California Warning  
Label  
If installation is in California, select a location on the heater access panel. Be sure  
the surface is clean and dry and adhere the label.  
If the heater is being installed in the Commonwealth of Massachusetts, these units  
must be installed by a licensed plumber or licensed gas fitter.  
Massachusetts  
Requirement  
Refer to the limited warranty information on the Warranty Card in the "Owner's  
Envelope".  
3. Warranty  
Warranty is void if ...  
a. Wiring is not in accordance with the diagram furnished with the heater.  
b. The unit is installed without proper clearance to combustible materials.  
c. A fan model is connected to a duct system or if the air delivery system is  
modified.  
4. Uncrating and  
Preparation  
This unit was test operated and inspected at the factory prior to crating and was in  
operating condition. If the heater has incurred any damage in shipment, document  
the damage with the transporting agency and contact an authorized Reznor Dis-  
tributor. If you are an authorized Distributor, follow the FOB freight policy proce-  
dures as published by Thomas & Betts for Reznor products.  
Check the rating plate for the gas specifications and electrical characteristics of the  
heater to be sure that they are compatible with the gas and electric supplies at the  
installation site.  
Read this booklet and become familiar with the installation requirements of your  
particular heater. If you do not have knowledge of local requirements, check with  
the local gas company or any other local agencies who might have requirements  
concerning this installation.  
Before beginning, make preparations for necessary supplies, tools, and manpower.  
If the installation includes optional vertical louvers, downturn nozzle, ceiling mount-  
ing bracket, hanger kit, high altitude kit, multiple heater control, and/or stepdown  
transformer, install these options before the heater is suspended. Follow the in-  
structions included in the option package; option packages are shipped separately.  
Other shipped separate items could include a vent/combustion air kit, high tem-  
perature tape, a thermostat bracket kit, a thermostat, and/or a thermostat guard. Be  
sure all options ordered are at the installation site.  
IMPORTANT: Shipping brackets are attached with cabinet screws. When  
removing shipping brackets, re-insert ALL screws into the cabinet.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 3  
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5. Dimensions  
M and N - Hanger Dimensions for both 2-pt and 4-pt Suspension  
FIGURE 1 - Model UDAP,  
Power Vented Fan Model  
M
N
R - Hanger  
Dimension for  
2-pt Suspension  
Combustion  
P and Q -  
Hanger  
P
Air Inlet  
Dimensions  
for 4-pt  
R
Thermostat  
REAR  
VIEW  
Connection  
Suspension  
TOP VIEW  
(30-125 Vertical;  
150-400 Horizontal)  
Q
3/8”-16 Female Thread  
- all suspension points  
G
J
Line Voltage  
Inlet (connects  
at circuit board)  
Vent Collar  
(see Technical  
Data for size)  
External  
Gas  
Connection  
K
H
B
E
F
1-1/4  
(32)  
D
FRONT  
VIEW  
RIGHT SIDE  
VIEW  
(Access Panel)  
C
A
MODEL UDAP DIMENSIONS (inches 1/16)  
Size  
A
B
C
D
E
F
G
H
J
K
M
N
P
Q
13  
13  
13  
13  
13  
R
30, 45 12-1/8 26-5/8  
60  
75  
10 13-13/16 26 21-9/16 5-3/16 6-1/2 2-11/16 3-7/8 17-3/8 11/16 4-5/16  
13 13-13/16 27 21-9/16 7-7/8  
13 13-13/16 27-5/8 21-9/16 7-7/8  
21 13-13/16 28-5/8 21-9/16 14-1/2 6-1/2  
21 13-13/16 29-3/8 21-9/16 14-1/2 6-1/2  
9-9/16  
10-1/2  
10-1/2  
10-1/2  
10-1/2  
15-1/8 26-5/8  
15-1/8 26-5/8  
23-1/8 26-5/8  
23-1/8 26-5/8  
6-1/2  
6-1/2  
5-1/2  
5-1/2  
8-3/4  
8-3/4  
3-7/8 17-3/8 11/16 4-5/16  
3-7/8 17-3/8 11/16 4-5/16  
3-7/8 17-3/8 11/16 4-5/16  
3-7/8 17-3/8 11/16 4-5/16  
100  
125  
150, 175,  
200  
225, 250 26-1/8 38-3/16 22  
300, 350,  
400  
20-1/8 38-3/16 16  
23  
23  
23  
42  
42  
42  
35-3/8 8-1/2  
8-1/4  
5-7/16 6-1/2 25-11/16 1-3/8 8-3/16 22-3/16 16-3/8  
6-1/2 25-11/16 1-3/8 8-3/16 22-3/16 15-5/8  
11-13/16 7-5/16 27-11/16 1-3/8 8-3/16 22-3/16 16-3/16  
35-3/8 13-1/16 8-13/16  
9
34-1/8  
41  
30  
35-3/8 17-1/16  
9
MODEL UDAP DIMENSIONS (mm 2)  
Size  
30, 45  
60  
A
B
C
D
E
F
G
H
J
68  
140  
140  
222  
222  
K
98  
98  
98  
98  
98  
M
N
17  
17  
17  
17  
17  
P
Q
R
308  
384  
384  
587  
587  
676  
676  
676  
676  
676  
254  
330  
330  
533  
533  
351  
351  
351  
351  
351  
660  
686  
702  
727  
746  
548  
548  
548  
548  
548  
132  
200  
200  
368  
368  
165  
165  
165  
165  
165  
441  
441  
441  
441  
441  
110  
110  
110  
110  
110  
330  
330  
330  
330  
330  
243  
267  
267  
267  
267  
75  
100  
125  
150, 175,  
200  
225, 250 664  
300, 350,  
400  
511  
970  
970  
406  
559  
762  
584  
584  
584  
1067  
1067  
1067  
899  
899  
899  
216  
332  
433  
210  
224  
229  
138  
229  
300  
165  
165  
186  
652  
652  
703  
35  
35  
35  
208  
208  
208  
564  
564  
564  
416  
397  
411  
867  
1041  
Option CD3  
Options CD2 and CD4  
Size  
30, 45  
60, 75  
100, 125  
150, 175, 200  
225, 250  
300, 350, 400  
FIGURE 2 -  
With Optional  
Downturn Nozzle  
Dimension “U”  
-- Applies to both  
UDAP and UDAS  
inches  
7-1/8  
mm  
181  
219  
321  
292  
368  
470  
inches  
mm  
314  
381  
556  
505  
638  
813  
With  
With  
Option  
CD3  
12-3/8  
15  
Option  
CD2  
8-5/8  
or CD4  
12-5/8  
11-1/2  
14-1/2  
18-1/2  
21-7/8  
19-7/8  
25-1/8  
32  
U
U
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 4  
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FIGURE 3 - Model UDAS,  
Separated Combustion Fan  
Model  
M and N - Hanger Dimensions  
for both 2-pt and 4-pt Suspension  
M
N
R - Hanger  
Dimension for  
2-pt Suspension  
Combustion Air Connection  
(see Technical Data for size)  
T
P
Thermostat  
S
R
REAR  
VIEW  
Connection  
(30-45, 150-400  
Horizontal;  
TOP VIEW  
P and Q -  
Hanger  
60-125 Vertical)  
Dimensions  
for 4-pt  
Q
3/8”-16 Female Thread  
- all suspension points  
Suspension  
G
J
Line Voltage  
Vent Connection  
(see Technical  
Data for size)  
External  
Gas  
Connection  
K
Inlet (connects in  
H
sealed electrical box)  
B
E
D
1-1/4  
(32)  
F
RIGHT SIDE  
VIEW  
(Access Panel)  
C
FRONT  
VIEW  
A
MODEL UDAS DIMENSIONS (inches 1/16)  
Size  
A
B
C
D
E
F
G
H
J
K
M
N
P
Q
R
S
T
30, 45 12-1/8 26-5/8 10 13-13/16 26 21-9/16 5-3/16 6-1/2 2-11/16 3-7/8 17-3/8 11/16 4-5/16 13  
60 15-1/8 26-5/8 13 13-13/16 27 21-9/16 7-7/8 6-1/2 5-1/2 3-7/8 17-3/8 11/16 4-5/16 13  
75 15-1/8 26-5/8 13 13-13/16 27-5/8 21-9/16 7-7/8 6-1/2 5-1/2 3-7/8 17-3/8 11/16 4-5/16 13  
100 23-1/8 26-5/8 21 13-13/16 28-5/8 21-9/16 14-1/2 6-1/2 8-3/4 3-7/8 17-3/8 11/16 4-5/16 13  
125 23-1/8 26-5/8 21 13-13/16 29-3/8 21-9/16 14-1/2 6-1/2 8-3/4 3-7/8 17-3/8 11/16 4-5/16 13  
150,  
9-9/16 2-15/16 2-15/16  
10-1/2 3-1/4 2-15/16  
10-1/2 3-1/4 2-15/16  
10-1/2 4-5/8 2-15/16  
10-1/2 4-5/8 2-15/16  
20-1/8 38-3/16 16  
23  
23  
23  
42 35-3/8 8-1/2 8-1/4 5-7/16 6-1/2 25-11/16 1-3/8 8-3/16 22-3/16 16-3/8 4-1/8 8-5/16  
42 35-3/8 13-1/16 8-13/16 6-1/2 25-11/16 1-3/8 8-3/16 22-3/16 15-5/8 5-9/16 8-5/16  
11-13/16 7-5/16 27-11/16 1-3/8 8-3/16 22-3/16 16-3/16 9-1/16 8-9/16  
175,  
200  
225,  
250  
300,  
350,  
400  
26-1/8 38-3/16 22  
9
34-1/8 41  
30  
42 35-3/8 17-1/16  
9
MODEL UDAS DIMENSIONS (mm 2)  
Size  
30, 45 308  
60  
A
B
C
D
E
F
G
H
J
68  
140  
140  
222  
222  
K
M
N
17  
17  
17  
17  
17  
P
Q
R
S
75  
T
676 254 351  
676 330 351  
676 330 351  
676 533 351  
676 533 351  
660  
686  
702  
727  
746  
548  
548  
548  
548  
548  
132  
200  
200  
368  
368  
165  
165  
165  
165  
165  
98  
98  
98  
98  
98  
441  
441  
441  
441  
441  
110  
110  
110  
110  
110  
330  
330  
330  
330  
330  
243  
267  
267  
267  
267  
75  
75  
75  
75  
75  
384  
384  
587  
587  
89  
75  
89  
100  
125  
150,  
175,  
200  
225,  
250  
300,  
350,  
400  
117  
117  
511  
664  
970 406 584  
970 559 584  
1067 899  
1067 899  
1067 899  
216  
332  
433  
210  
224  
229  
138  
229  
300  
165  
165  
186  
652  
652  
703  
35  
35  
35  
208  
208  
208  
564  
564  
564  
416  
397  
411  
105  
141  
230  
211  
211  
217  
867 1041 762 584  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 5  
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6.Technical Data  
(Data applies to both Models UDAP and UDAS unless noted otherwise.)  
TECHNICAL DATA - Sizes 30 - 125  
Size  
30  
30,000  
8.8  
45  
45,000  
13.2  
83  
60  
60,000  
17.6  
83  
75  
75,000  
22.0  
83  
100  
105,000  
30.8  
83  
125  
120,000  
35.2  
83  
BTUH  
Input Heating Capacity  
kw  
Thermal Efficiency (%)  
82  
BTUH  
kw  
24,600  
7.2  
1/2  
37,350  
11.0  
1/2  
49,800  
14.6  
1/2  
62,250  
18.3  
1/2  
87,150  
25.6  
1/2  
99,600  
29.2  
1/2  
Output Heating Capacity A  
Natural  
Gas Connection (inches) B  
Propane  
1/2  
1/2  
1/2  
1/2  
1/2  
1/2  
Vent Connection C (inches diameter)  
4
4
4
4
4
4
C
4
4
4
4
4
4
Combustion Air Inlet (inches diameter) - UDAS only  
Control Amps (24 volt)  
1.0  
1.0  
1.0  
1.0  
1.0  
1.0  
Full Load Amps (115 volt)  
1.9  
15  
109  
50  
2.4  
15  
155  
55  
2.4  
15  
155  
60  
3.3  
15  
217  
60  
3.9  
15  
276  
60  
5.1  
15  
354  
60  
Maximum Over Current Protection (115V) D  
Normal Power Consumption (watts)  
Discharge Air Temperature Rise (°F)  
CFM  
456  
12.9  
0.96  
0.09  
475  
145  
0.02  
N.A.  
1550  
10  
629  
17.8  
0.96  
0.09  
656  
200  
0.03  
N.A.  
1550  
10  
769  
21.8  
1.25  
0.12  
616  
188  
0.03  
N.A.  
1550  
12  
961  
27.5  
1.25  
0.12  
770  
238  
0.06  
N.A.  
1550  
12  
1345  
36.7  
2.01  
0.19  
668  
196  
1/30  
1/4  
1537  
45.9  
2.01  
0.19  
763  
245  
1/20  
1/4  
Air Volume  
M3/minute  
ft2  
Discharge Air Opening Area  
M2  
FPM  
M/minute  
Open  
Enclosed  
Output Velocity  
Fan Motor HP E  
Fan Motor RPM  
Fan Diameter (inches)  
1050  
16  
1050  
16  
Sound Level  
dba @ 15 ft  
40  
40  
40  
49  
54  
55  
(Data applies to both Models UDAP and UDAS unless noted otherwise.)  
TECHNICAL DATA - Sizes 150 - 400  
Size  
150  
175  
200  
225  
250  
300  
350  
400  
BTUH  
150,000  
43.9  
83  
175,000  
51.2  
83  
200,000  
58.6  
83  
225,000  
65.9  
83  
250,000  
73.2  
83  
300,000  
87.8  
83  
350,000  
102.5  
83  
400,000  
117.1  
83  
Input Heating Capacity  
kw  
Thermal Efficiency (%)  
BTUH  
kw  
124,500  
36.4  
1/2  
1/2  
5
145,250  
42.5  
1/2  
1/2  
5
166,000  
48.6  
1/2  
1/2  
5
186,750  
54.7  
3/4  
3/4  
5
207,500  
60.8  
3/4  
3/4  
5
249,000  
72.9  
3/4  
3/4  
6
290,500  
85.1  
3/4  
3/4  
6
332,000  
97.2  
3/4  
3/4  
6
Output Heating Capacity A  
Natural  
Gas Connection (inches) B  
Propane  
Vent Connection C (inches diameter)  
C
6
6
6
6
6
6
6
6
Combustion Air Inlet (inches diameter) - UDAS only  
Control Amps (24 volt)  
1.0  
1.0  
1.0  
1.0  
1.0  
1.0  
1.0  
1.0  
Full Load Amps (115 volt)  
3.8  
15  
392  
60  
3.8  
15  
392  
60  
4.6  
15  
491  
60  
7.5  
15  
747  
60  
7.5  
15  
747  
60  
10.7  
20  
1086  
60  
10.7  
20  
1086  
60  
10.7  
20  
1086  
60  
Maximum Over Current Protection (115V) D  
Normal Power Consumption (watts)  
Discharge Air Temperature Rise (°F)  
CFM  
1921  
54.4  
2.56  
0.24  
752  
229  
1/6  
2242  
63.5  
2.56  
0.24  
877  
267  
1/6  
2562  
72.5  
2.56  
0.24  
1003  
306  
1/6  
2882  
81.6  
3.51  
0.33  
820  
250  
1/4  
3202  
90.7  
3.51  
0.33  
911  
278  
1/4  
3843  
108.8  
4.79  
0.45  
802  
244  
1/2  
4483  
126.9  
4.79  
0.45  
936  
285  
1/2  
5123  
145.1  
4.79  
0.45  
1069  
326  
1/2  
Air Volume  
M3/minute  
ft2  
Discharge Air Opening Area  
M2  
FPM  
Output Velocity  
M/minute  
Open  
Enclosed  
Fan Motor HP E  
1/4  
1/4  
1/4  
1/4  
1/4  
1/2  
1/2  
1/2  
Fan Motor RPM  
Fan Diameter (inches)  
1050  
18  
1050  
18  
1050  
18  
1050  
20  
1050  
20  
1050  
24  
1050  
24  
1050  
24  
Sound Level  
dba @ 15 ft  
51  
52  
53  
56  
56  
59  
61  
62  
A
B
CSA ratings for altitudes to 2000 ft.  
Size shown is for gas connection to a single-stage gas valve, not supply line size.  
C
Smaller and/or larger vent and combustion air pipe diameters may be permissible. For Model UDAS refer to the Venting Installation Manual for Separated  
Combustion Units. For Model UDAP refer to the Venting Installation Manual for Power Vented units. For a Model UDAP with Option AV6, refer to the  
Venting Installation Manual for Common Venting.  
D
MOCP = 2.25 x (largest motor FLA) + smallest motor FLA. Answer is rounded to the next lower standard circuit breaker size.  
E
All other information is this table is based on a heater equipped with a standard 115 volt open fan motor.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 6  
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If the heater is being installed at an elevation above 2000 ft (610M), the input rate  
will have to be derated. This is done by adjusting the valve outlet pressure.  
7. High Altitude  
Operation  
In addition, if the heater is being installed at an altitude above 6000 ft (1830M), the  
pressure switch will have to be changed. If ordered with the unit as Option DJ20 or  
DJ21, the pressure switch is shipped separately.  
Gas valve adjustment for  
high altitude can only be  
done after heater is  
operating; see  
Adjusting the valve outlet pressure is done after the heater is in operation; follow  
the instructions in Paragraph 12. Capacities and inputs for derated units are also  
listed in Paragraph 12.  
If the pressure switch needs to be changed, do that before the heater is operated;  
follow the instructions in FIGURE 4.  
Paragraph 12.  
FIGURE 4 - Installing High Altitude Pressure Switch required above 6000 ft (1830M) elevation  
Model UDAP  
Size  
30  
45  
60 75  
100  
125  
150 175 200 225 250 300 350 400  
High Altitude Switch P/N  
Negative Pressure OFF Setpoint "w.c.  
Label color  
197031  
0.35  
Purple  
197032  
0.45  
Pink  
197031  
0.35  
Purple  
201160  
1.00  
Brown  
201161  
1.30  
White  
Model UDAP-CV with Option AV6 for Common Venting  
Size  
30  
197029 197032 196362 196388  
0.60 0.45 0.55 0.50  
Lt Blue Pink White Orange  
45  
60 75  
100  
High Altitude Switch P/N  
Negative Pressure OFF Setpoint "w.c.  
Label color  
Model UDAS  
Size  
30  
45  
60 75  
100  
125  
150 175 200 225 250 300 350 400  
High Altitude Switch P/N  
Differential Pressure OFF Setpoint "w.c.  
Label color  
197029  
0.60  
Lt. Blue  
196388 197030 197031  
201160  
1.00  
Brown  
201161  
1.30  
White  
0.50  
0.40  
0.35  
Orange Green  
Purple  
Instructions for Changing Pressure Switch  
1. In the control compartment, locate the pressure switch.  
Sizes 30-125 - On the back wall of the control compartment.  
Sizes 150-400 - On the bracket on the bottom of the control compartment.  
2. Mark and disconnect the two wires attached to the pressure switch.  
3. Disconnect the sensing tube from the pressure switch.  
4. Locate the two screws holding the switch mounting bracket. Remove the  
screws (save screws) and the pressure switch.  
Pressure Switch  
5. Using the same screws, install the high altitude pressure switch. Attach the  
sensing tube and wires.  
Units must be installed so that the clearances in the table are provided for combus-  
tion air space, inspection and service, and for proper spacing from combustible  
construction. Clearance to combustibles is defined as the minimum distance from  
the heater to a surface or object that is necessary to ensure that a surface tempera-  
ture of 90°F above the surrounding ambient temperature is not exceeded.  
8. Clearances  
Clearances  
Top  
inches mm  
Flue Connector  
Access Panel  
Non-Access Side  
Bottom*  
inches mm inches mm  
Rear  
Size  
inches  
mm  
152  
152  
inches  
mm  
457  
457  
inches  
mm  
25  
51  
30-125  
1
4
25  
6
6
18  
1
2
1
1
25  
25  
18  
18  
457  
457  
150-400  
102  
18  
*Suspend the heater so that the bottom is a minimum of 5 feet (1.5M) above the floor.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 7  
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This heater must be supplied with the air that enters into the combustion process  
and is then vented to the outdoors. Sufficient air must enter the equipment location  
to replace that exhausted through the heater vent system. In the past, the infiltra-  
tion of outside air assumed in heat loss calculations (one air change per hour) was  
assumed to be sufficient. However, current construction methods using more insu-  
lation, vapor barriers, tighter fitting and gasketed doors and windows, weather-  
stripping, and/or mechanical exhaust fans may now require the introduction of  
outside air through wall openings or ducts.  
9. Combustion  
Air - applies to  
Model UDAP  
and Model  
UDAP-CV  
The requirements for combustion and ventilation air depend upon whether the unit  
is located in a confined or unconfined space. An "unconfined space" is defined as  
a space whose volume is not less than 50 cubic feet per 1000 BTUH of the installed  
appliance. Under ALL conditions, enough air must be provided to ensure there  
will not be a negative pressure condition within the equipment room or space.  
(Note: For Model  
UDAS, see Venting  
Manual for  
combustion air  
requirements.)  
WARNING: Model UDAP and UDAP-CV power-vented unit  
heaters are designed to take combustion air from the space in  
which the unit is installed and are not designed for connection to  
outside combustion air intake ducts. Connecting outside air ducts  
voids the warranty and could cause hazardous operation. See  
Hazard Levels, page 2.  
Do not install a unit in a confined space without providing wall openings leading  
to and from the space. Provide openings near the floor and ceiling for ventilation  
and air for combustion as shown in FIGURE 5, depending on the combustion air  
source as noted in Items 1, 2, and 3 below.  
Combustion Air  
Requirements for  
a Heater Located  
in a Confined  
Add total BTUH of all appliances in the confined space and divide by figures  
below for square inch free area size of each (top and bottom) opening.  
Space - applies to  
Model UDAP and  
Model UDAP-CV  
Confined Space:  
A space whose volume is  
less than 50 cubic feet  
per 1000 BTUH of the  
installed appliance input  
rating  
(2)  
(2)  
(3)  
(1)  
Confined  
Space  
FIGURE 5 - Definition of  
Confined Space and  
Required Openings for  
Combustion Air  
(3)  
(1)  
1. Air from inside the building -- openings 1 square inch free area per 1000  
BTUH. Never less than 100 square inches free area for each opening. See (1) in  
FIGURE 5.  
2. Air from outside through duct -- openings 1 square inch free area per 2000  
BTUH. See (2) in FIGURE 5.  
3. Air direct from outside -- openings 1 square inch free area per 4000 BTUH.  
See (3) in FIGURE 5.  
NOTE: For further details on supplying combustion air to a confined space, see  
the National Fuel Gas Code ANSI Z223.1a (latest edition).  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 8  
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Use the sound data in Paragraph 6, clearances in Paragraph 8; the combustion air  
requirements in Paragraph 9; the throw tables, mounting height requirements, and  
location recommendations below; the weights in Paragraph 11; and the venting  
requirements in the Venting Manual to determine where to suspend the heater.  
10. Unit Heater  
Location  
Heater Throw  
*Louver angle listed in the table is relative to the top of the heater.  
FIGURE 6 - Throw for Fan  
Models UDAP and UDAS  
NOTE: Throws listed are with  
standard adjustable horizontal  
louvers at the angles listed  
(angle is relative to the top of  
the heater). Throw pattern  
changes with the addition of  
optional vertical louvers and/or  
downturn nozzles.  
H
**“Z” is the point  
X
when the air velocity  
Y
drops below 50 feet  
(15.2M) per minute.  
Z**  
Dimensions X, Y, and Z (feet) Model UDAP and Model UDAS with Standard Horizontal Louvers at Mounting Heights of 5 - 18 ft  
30  
45  
60  
75  
100  
125  
H
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
5 ft  
8 ft  
6
7
6
-
-
-
14 30 -21°  
13 26 -39°  
11 22 -52°  
7
9
9
8
-
16 40 -20°  
8
18 45 -16°  
9
20 57 -14°  
9
20 59 -18° 10 22  
65 -14°  
63 -24°  
60 -30°  
57 -36°  
53 -43°  
47 -50°  
40 -57°  
16 37 -34° 10 18 42 -29° 12 22 54 -25° 11 21 56 -28° 12 23  
15 33 -43° 10 17 39 -37° 12 22 52 -32° 12 20 52 -36° 13 24  
12 27 -55° 10 16 34 -46° 12 21 48 -39° 11 19 47 -44° 14 23  
10 ft  
12 ft  
14 ft  
16 ft  
18 ft  
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
9
-
-
14 29 -56° 12 19 44 -46° 11 17 42 -51° 14 22  
-
-
-
-
-
-
-
-
11 17 38 -54° 10 14 34 -58° 13 20  
-
-
-
-
-
-
-
-
-
11 17  
150  
175  
200  
225  
250  
300  
350  
400  
H
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
8 ft 13 24 73 -26° 15 28 90 -22° 16 30 93 -20° 14 27 86 -24° 16 29 93 -21° 15 28  
10 ft 14 24 69 -32° 17 29 87 -27° 17 31 91 -25° 15 27 82 -30° 17 30 90 -26° 16 28  
12 ft 14 24 64 -39° 18 29 84 -32° 18 31 88 -30° 16 27 78 -35° 18 30 87 -31° 17 28  
14 ft 14 22 59 -45° 18 28 79 -37° 19 30 84 -34° 16 26 73 -41° 18 30 83 -36° 17 27  
16 ft 13 20 53 -51° 18 27 74 -42° 19 29 79 -39° 16 24 67 -47° 19 28 78 -41° 17 25  
18 ft 11 17 44 -58° 17 26 68 -48° 19 28 74 -44° 14 22 60 -53° 18 27 72 -46° 16 24  
94 -24° 17 31 105 -20° 18 34 113 -17°  
89 -29° 18 32 103 -25° 20 35 110 -21°  
85 -34° 19 32 98 -30° 21 36 108 -25°  
80 -40° 20 32 95 -34° 23 35 105 -29°  
74 -45° 21 31 90 -38° 23 35 101 -33°  
66 -51° 20 30 85 -43° 23 35 97 -37°  
Dimensions X, Y, and Z (meters) Model UDAP and Model UDAS with Standard Horizontal Louvers at Mounting Heights of 1.5 - 5.5M  
30  
45  
60  
75  
100  
125  
H
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
1.5 M 1.8 4.3 9.1 -21° 2.1 4.9 12.2 -20° 2.4 5.5 13.8 -16° 2.7 6.1 17.4 -14° 2.7 6.1 18.0 -18° 3.0 6.7 19.9 -14°  
2.4 M 2.1 4.0 7.9 -39° 2.7 4.9 11.3 -34° 3.0 5.5 12.8 -29° 3.7 6.7 16.5 -25° 3.4 6.4 17.1 -28° 3.7 7.0 19.2 -24°  
3.0 M 1.8 3.4 6.7 -52° 2.7 4.6 10.0 -43° 3.0 5.2 11.9 -37° 3.7 6.7 15.8 -32° 3.7 6.1 15.8 -36° 4.0 7.3 18.3 -30°  
3.7 M  
4.3 M  
4.9 M  
5.5 M  
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2.4 3.7 8.2 -55° 3.0 4.9 10.4 -46° 3.7 6.4 14.6 -39° 3.4 5.8 14.3 -44° 4.3 7.0 17.4 -36°  
-
-
-
-
-
-
-
-
-
-
-
-
2.7 4.3 8.8 -56° 3.7 5.8 13.4 -46° 3.4 5.2 12.8 -51° 4.3 6.7 16.1 -43°  
-
-
-
-
-
-
-
-
3.4 5.2 11.6 -54° 3.0 4.3 10.4 -58° 4.0 6.1 14.3 -50°  
-
-
-
-
-
-
-
-
3.4 5.2 12.2 -57°  
150  
175  
200  
225  
250  
300  
350  
400  
H
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
X
Y
Z
2.4 M 4.0 7.3 22.3 -26° 4.6 8.5 27.4 -22° 4.9 9.1 28.0 -20° 4.3 8.2 26.2 -24° 4.9 8.8 28.3 -21° 4.6 8.5 28.7 -24° 5.2 9.4 32.0 -20° 5.5 11.3 34.4 -17°  
3.0 M 4.3 7.3 21.0 -32° 5.2 8.8 26.6 -27° 5.2 9.4 27.7 -25° 4.6 8.2 25.0 -30° 5.2 9.1 27.4 -26° 4.9 8.5 27.1 -29° 5.5 9.8 31.4 -25° 6.1 10.7 33.5 -21°  
3.7 M 4.3 7.3 19.5 -39° 5.5 8.8 25.6 -32° 5.5 9.4 26.8 -30° 4.9 8.2 23.8 -35° 5.5 9.1 26.5 -31° 5.2 8.5 25.9 -34° 5.8 9.8 29.9 -30° 6.4 11.0 32.9 -25°  
4.3 M 4.3 6.7 18.0 -45° 5.5 8.5 24.1 -37° 5.8 9.1 25.6 -34° 4.9 7.9 22.3 -41° 5.5 9.1 25.3 -36° 5.2 8.2 24.4 -40° 6.1 9.8 29.0 -34° 7.0 10.7 32.0 -29°  
4.9 M 4.0 6.1 16.2 -51° 5.5 8.2 22.6 -42° 5.8 8.8 24.1 -39° 4.9 7.3 20.4 -47° 5.8 8.5 23.8 -41° 5.2 7.6 22.6 -45° 6.4 9.4 27.4 -38° 7.0 10.7 30.8 -33°  
5.5 M 3.4 5.2 13.4 -58° 5.2 7.9 20.7 -48° 5.8 8.5 22.6 -44° 4.3 6.7 18.3 -53° 5.5 8.2 21.9 -46° 4.9 7.3 20.1 -51° 6.1 9.1 25.9 -43° 7.0 10.7 26.9 -37°  
Locate the heater so that it is a minimum of five feet (1.5M) above the floor and in  
compliance with the clearances in Paragraph 8.  
Location  
Recommendations  
WARNING: If touched, the vent pipe and internal heater surfaces  
that are accessible from outside the heater will cause burns.  
Suspend the heater a minimum of 5 feet (1.5M) above the floor.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 9  
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For best results, the heater should be placed with certain rules in mind. In general,  
a unit should be located from 8 to 12 feet (2.4-3.7M) above the floor. Units should  
always be arranged to blow toward or along exposed wall surfaces, if possible.  
Where two or more units are installed in the same room, a general scheme of air  
circulation should be maintained for best results.  
10. Unit Heater  
Location  
(cont’d)  
Suspended heaters are most effective when located as close to the working zone as  
possible, and this fact should be kept in mind when determining the mounting  
heights to be used. However, care should be exercised to avoid directing the dis-  
charged air directly on the room occupants.  
NOTE: Venting  
requirements may  
affect location.  
Consult the Venting  
Manual for this heater  
before making final  
determination.  
Partitions, columns, counters, or other obstructions should be taken into consider-  
ation when locating the unit heater so that a minimum quantity of airflow will be  
deflected by such obstacles.  
When units are located in the center of the space to be heated, the air should be  
discharged toward the exposed walls. In large areas, units should be located to  
discharge air along exposed walls with extra units provided to discharge air in  
toward the center of the area.  
At those points where infiltration of cold air is excessive, such as at entrance doors  
and shipping doors, it is desirable to locate the unit so that it will discharge directly  
toward the source of cold air from a distance of 15 to 20 feet (4.6-6.1M).  
CAUTION: Do not locate the heater where it may be exposed to  
water spray, rain, or dripping water.  
The presence of chlorine vapors in the combustion air of gas-fired heating equip-  
ment presents a potential corrosion hazard. Chlorine found usually in the form of  
freon or degreaser vapors, when exposed to flame will precipitate from the com-  
pound, and go into solution with any condensation that is present in the heat ex-  
changer or associated parts. The result is hydrochloric acid which readily attacks  
all metals including 300 grade stainless steel. Care should be taken to separate  
these vapors from the combustion process. This may be done by wise location of  
the unit vent and combustion air terminals with regard to exhausters or prevailing  
wind directions. Chlorine is heavier than air. Keep these facts in mind when deter-  
mining installation location of the heater in relation to building exhaust systems.  
Hazards of Chlorine -  
applies to location of  
Model UDAS heater  
with regard to  
combustion air inlet  
Before suspending the heater, check the supporting structure to be used to verify  
that it has sufficient load-carrying capacity to support the weight of the unit.  
11. Hanging the  
Heater  
Model UDAP  
Size  
lbs  
30 45 60 75 100  
125  
101  
46  
150 175, 200 225  
250  
215  
98  
300  
269  
122  
350  
294  
133  
400  
306  
139  
WARNINGS: Check the  
supporting structure to  
be used to verify that it  
has sufficient load carry-  
ing capacity to support  
the weight of the unit.  
Suspend the heater only  
from the threaded nut  
retainers or with a man-  
ufacturer provided kit.  
Do NOT suspend from  
the heater cabinet.  
54 59 67 72  
24 27 30 33  
96  
44  
172  
78  
187  
85  
203  
92  
kg  
Model UDAS  
Size  
lbs  
30 45 60 75 100  
125  
102  
46  
150 175, 200 225  
250  
216  
98  
300  
270  
122  
350  
295  
134  
400  
307  
138  
55 60 68 73  
25 27 31 33  
97  
44  
173  
78  
188  
85  
204  
93  
kg  
When the heater is lifted for suspension, support the bottom of the heater with  
plywood or other appropriately placed material. If the bottom is not supported,  
damage could occur. Before hanging, verify that all screws used for holding ship-  
ping brackets were re-installed in the cabinet.  
The heater is equipped for either two-point or four-point suspension. A 3/8"-16  
threaded nut retainer is located at each suspension point. See Dimensions in Para-  
graph 5 and the illustration in FIGURE 7A.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 10  
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FIGURE 7A - Suspending  
the Heater with Rods from  
the Threaded Nut Retainers  
(either two or four point  
suspension)  
Be sure the threaded hanger rods  
are locked to the heater as  
illustrated.  
3/8” threaded rod  
(field supplied)  
Add a 3/8” nut and  
washer to lock the  
hanger rod to the heater.  
WARNING: Unit must  
be level for proper  
operation. Do not place  
or add additional weight  
to the suspended heater.  
Hazard Levels, page 2.  
Recommended maximum hanger  
rod length is 6 feet (1.8M).  
If ordered with swivel connectors for 1” pipe, Option CK8 or CK10, attach the  
swivels at the threaded nut retainers. Suspend with 1” pipe. (See FIGURE 7B.)  
Be sure the  
Lock the swivel  
connector to  
the heater.  
The connector  
is threaded for  
hanging from  
a 1” pipe.  
threaded swivel  
connectors are  
locked to the  
heater as  
FIGURE 7B - Swivel  
Connectors to Suspend the  
Heater from 1” Pipe, Option  
CK8 (2-pt) or CK10 (4-pt)  
illustrated.  
If ordered with a ceiling suspension kit, Option CK22, follow the illustrated in-  
structions in the kit. (See FIGURE 8.)  
FIGURE 8 - Suspending the  
Heater using Option CK22,  
Ceiling Suspension Kit (no  
hanger rods)  
Available for  
Sizes 30-125.  
Allows the  
heater to be  
installed one  
inch from the  
ceiling.  
NOR  
Model UDAS - Whether using the suspension points or the hanger kit, when in-  
stalling a Model UDAS, the unused suspension points on the control side of the  
heater MUST be plugged. Plug these holes with the 3/8”-16 bolts and flat wash-  
ers shipped in the bag with the heater. (See FIGURE 9.)  
FIGURE 9 - Model UDAS -  
Plug the unused suspension  
points on the control side of  
the heater with 3/8”-16  
Plug any unused suspension points  
on the control side with the 3/8”-16  
bolts and flat washers provided.  
screws and flat washers  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 11  
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WARNING: This appliance is equipped for a maximum gas  
supply pressure of 1/2 pound, 8 ounces, or 14 inches water column.  
Supply pressure higher than 1/2 pound requires installation of  
an additional lockup-type service regulator external to the unit.  
12. Gas Piping  
and  
Pressures  
WARNING: PRESSURE TESTING SUPPLY PIPING  
Test Pressures Above 1/2 PSI: Disconnect the heater and manual valve from the  
gas supply line which is to be tested. Cap or plug the supply line.  
Test Pressures Below 1/2 PSI: Before testing, close the manual valve on the  
heater.  
Sizing  
Gas  
Supply  
Capacity of Piping  
Cubic Feet per Hour based on 0.3" w.c. Pressure Drop  
Specific Gravity for Natural Gas -- 0.6 (Natural Gas -- 1000 BTU/Cubic Ft)  
Specific Gravity for Propane Gas -- 1.6 (Propane Gas -- 2550 BTU/Cubic Ft)  
Diameter of Pipe  
Length  
of  
Line  
1/2"  
3/4"  
1"  
1-1/4"  
1-1/2"  
2"  
Pipe Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane  
20’  
30’  
40’  
50’  
60’  
70’  
80’  
90’  
100’  
125’  
150’  
175’  
200’  
92  
73  
63  
56  
50  
46  
43  
40  
38  
34  
31  
28  
26  
56  
45  
38  
34  
31  
28  
26  
24  
23  
21  
19  
17  
16  
190  
152  
130  
115  
105  
96  
90  
84  
79  
72  
116  
93  
79  
70  
64  
59  
55  
51  
48  
44  
39  
36  
34  
350  
285  
245  
215  
195  
180  
170  
160  
150  
130  
120  
110  
100  
214  
174  
149  
131  
119  
110  
104  
98  
92  
79  
73  
67  
730  
590  
500  
440  
400  
370  
350  
320  
305  
275  
250  
225  
210  
445  
360  
305  
268  
244  
226  
214  
195  
186  
168  
153  
137  
128  
1100  
890  
760  
670  
610  
560  
530  
490  
460  
410  
380  
350  
320  
671  
543  
464  
409  
372  
342  
323  
299  
281  
250  
232  
214  
195  
2100  
1650  
1450  
1270  
1105  
1050  
990  
930  
870  
780  
710  
1281  
1007  
885  
775  
674  
641  
604  
567  
531  
476  
433  
397  
372  
64  
59  
55  
650  
610  
61  
Note: When sizing supply lines, consider possibilities of future expansion and increased requirements.  
Refer to National Fuel Gas Code for additional information on line sizing.  
All piping must be in accordance with requirements outlined in the National Fuel  
Gas Code ANSI/Z223.1a (latest edition) or CAN/CGA-B149.1 and B149.2 (See  
Paragraph 2). Gas supply piping installation should conform with good practice  
and with local codes. Support gas piping with pipe hangers, metal strapping, or  
other suitable material; do not rely on the heater to support the gas pipe.  
WARNING: All  
components of a gas  
supply system must be  
leak tested prior to  
placing equipment in  
service. NEVER TEST  
FOR LEAKS WITH AN  
OPEN FLAME. Failure  
to comply could result in  
personal injury,  
The heater is orificed for operation with natural gas having a heating value of 1000  
(± 50) BTUH per cubic ft or propane gas with a heating value of 2500 (± 100)  
BTUH per cubic ft. If the gas at the installation does not meet these specifications,  
consult the factory for proper orificing.  
Pipe joint compounds (pipe dope) shall be resistant to the action of liquefied petro-  
leum gas or any other chemical constituents of the gas being supplied.  
Install a ground joint union and manual shutoff valve upstream of the unit control  
system, as shown in FIGURE 10. Installation of a trap with a minimum 3" (76mm)  
drip leg is required.  
property damage or  
death.  
The unit is equipped with a nipple that extends outside the cabinet. The gas con-  
nection is either 1/2” or 3/4”.  
Gas Connection (inches)  
Gas Connection Size  
30 45 60 75 100 125 150 175 200 225 250 300 350 400  
Natural 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 3/4 3/4 3/4 3/4 3/4  
Propane 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 3/4 3/4 3/4 3/4 3/4  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 12  
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Leak-test all connections by brushing on a leak-detecting solution.  
FIGURE 10 - Gas  
Ground  
Joint Union  
connection is at the pipe  
nipple that extends outside  
the cabinet  
Manual shutoff  
To Gas Valve  
(inside the  
cabinet)  
Drip  
Leg  
From Gas Supply  
(horizontal or vertical)  
Illustration shows both a  
vertical and horizontal gas  
supply; requirements are  
the same.  
Pipe nipple extending  
outside the cabinet.  
Manual shutoff  
To Gas Valve  
(inside the  
cabinet)  
Drip  
Leg  
Ground  
Joint  
Union  
Measuring valve outlet gas pressure cannot be done until the heater is in opera-  
tion. It is included in the steps of the "Check-Test-Start" procedure in Paragraph  
24. The following warnings and instructions apply.  
Valve Outlet or  
Orifice Pressure  
Setting  
WARNING: Valve outlet gas pressure must never exceed 3.5"  
w.c. for natural gas and 10" w.c. for propane gas.  
NOTE: Gas Conversion  
Kits are available for  
For Natural Gas: When the heater leaves the factory, the combination gas valve  
is set so that the valve outlet gas pressure for a single stage valve or high fire of a  
two stage valve is regulated to 3.5" w.c. Inlet supply pressure to the valve for  
natural gas must be a minimum of 5" w.c. or as noted on the rating plate and a  
maximum of 14" w.c.  
changing from propane gas  
to natural gas or natural gas  
to propane gas. A factory-  
authorized conversion kit  
MUST be used.  
For Propane Gas: When the heater leaves the factory, the combination gas valve  
is set so that the valve outlet gas pressure for a single stage valve or high fire of a  
two stage valve is regulated to 10" w.c. Inlet supply pressure to the valve for  
propane gas must be a minimum of 11" w.c. and a maximum of 14" w.c.  
Before attempting to measure or adjust valve outlet gas pressure, the inlet supply  
pressure must be within the specified range both when the heater is in operation  
and on standby. Incorrect inlet pressure could cause excessive valve outlet gas  
pressure immediately or at some future time. If natural gas supply pressure is too  
high, install a regulator in the supply line before it reaches the heater. If natural  
gas supply pressure is too low, contact your gas supplier.  
Instructions  
Check Valve Outlet  
Pressure (can only be  
done after heater is  
operating)  
1) Locate the 1/8” output pressure tap on the valve (See FIGURE 11, page 14).  
With the manual valve turned off to prevent flow to the gas valve, connect a  
manometer to the 1/8" pipe outlet pressure tap in the valve. NOTE: A manom-  
eter (fluid-filled gauge) is recommended rather than a spring type gauge due to  
the difficulty of maintaining calibration of a spring type gauge.  
NOTE: If operating at high  
altitude, outlet pressure  
requires adjustment. Follow  
instructions on page 14.  
2) Open the manual valve and operate the heater. (NOTE: On Model UDAS,  
depress and hold the door safety switch.) Measure the outlet pressure of the gas  
valve. Normally when operating at sea level, adjustments should not be neces-  
sary to the factory setting. (For high altitude settings, see next paragraph.)  
If adjustment is necessary, remove the cap from the adjustment screw(s). Set  
pressure to correct settings by turning the regulator screw IN (clockwise) to  
increase pressure. Turn regulator screw OUT (counterclockwise) to decrease  
pressure.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 13  
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Instructions for High Altitude Derate  
12. Gas Piping  
and  
1. Determine the required valve outlet pressure for the elevation where the heater  
will be operating. If unsure of the elevation, contact the local gas supplier.  
Valve Outlet Pressure Settings by Elevation  
Pressures  
(cont’d)  
Manifold Pressure Settings by Altitude for the UNITED STATES  
Altitude  
Natural Gas (inches w.c.)  
Propane Gas (inches w.c.)  
Single Stage and Two Stage Single Stage and Two Stage  
Two Stage High Fire Low Fire Two Stage High Fire Low Fire  
Feet  
Meters  
Derate by Valve  
Outlet Pressure  
Adjustment for High  
Altitude Operation  
0-2000  
0-610  
3.5  
3.1  
3.0  
2.8  
2.7  
2.6  
2.5  
2.4  
2.3  
1.8  
1.6  
1.5  
1.5  
1.4  
1.3  
1.3  
1.2  
1.2  
10.0  
8.8  
8.5  
8.1  
7.7  
7.4  
7.1  
6.7  
6.7  
5.0  
4.4  
4.2  
4.1  
3.9  
3.7  
3.5  
3.4  
3.4  
2001-3000 611-915  
3001-4000 916-1220  
4001-5000 1221-1525  
5001-6000 1526-1830  
6001-7000 1831-2135  
7001-8000 2136-2440  
8001-9000 2441-2745  
9001-10000 2746-3045  
This adjustment can only  
be done after the heater is  
in operation. It is included  
in the startup procedures.  
Manifold Pressure Settings by Altitude for CANADA  
Natural Gas (inches w.c.) Propane Gas (inches w.c.)  
Altitude  
NOTE: If elevation is  
above 6000 ft (1830M), a  
high altitude pressure  
switch is required; see  
Paragraph 7.  
Single Stage and Two Stage Single Stage and Two Stage  
Two Stage High Fire Low Fire Two Stage High Fire Low Fire  
Feet  
Meters  
0-2000  
2001-4500 611-1373  
0-610  
3.5  
2.8  
1.8  
1.5  
10.0  
8.1  
5.0  
4.1  
2. Locate the 1/8” output pressure tap on the valve (See FIGURE 11). Turn the  
knob on the top of the valve to “OFF”. Connect a manometer to the 1/8" pipe  
outlet pressure tap in the valve. Use a water column manometer that is readable  
to the nearest tenth of an inch.  
FIGURE 11 - Top View of  
Valves showing Outlet  
Pressure Tap and  
3. Single Stage and Two Stage High Fire - Turn the knob on the top of the valve  
to “ON”. Remove the cap from the pressure adjusting screw and adjust the gas  
train pressure to the pressure selected from the table above. Adjust pressure by  
turning the regulator screw IN (clockwise) to increase pressure or OUT (coun-  
terclockwise) to decrease pressure.  
Adjustment Locations  
Single-Stage Valve  
Output  
1/8” Output  
Adjustment  
Pressure Tap  
Screw  
Two Stage Low Fire - Disconnect the wire from the “HI” terminal on the gas  
valve and check the low fire pressure. Turn the regulator screw to adjust the  
low fire outlet pressure to the “Low Fire” pressure selected from the table. Re-  
connect the wire to the gas valve.  
Inlet  
Pressure  
Tap  
4. Turn up the thermostat. (NOTE: On Model UDAS, depress and hold the door  
safety switch.) Cycle the burner once or twice to properly seat the adjustment  
spring in the valve.  
Re-check the pressure(s). When the outlet pressure is right for the installation,  
remove the manometer and replace the cap.  
Two -Stage Valve  
Check for leak at the pressure tap fitting.  
Adjust Low  
Pressure  
Output  
Adjust High  
Pressure  
Output  
5. With the heater operating determine that the inlet pressure to the heater for  
natural gas is between 5 and 13.5 inches w.c. and for propane between 10 and  
13.5 inches w.c. Take this reading as close as possible to the heater (Heaters are  
equipped with gas valves that have an inlet pressure tap.) If the inlet pressure is  
not within the specified range, the inlet pressure must be corrected and Steps 3  
and 4 repeated.  
Inlet  
Pressure  
Tap  
6. Find the High Altitude Adjustment label in the plastic bag that contained these  
instructions. Using a permanent marker, fill-in the appropriate information from  
the tables on page 15. Select a location for the label on the outside of the heater  
access panel so that it will be conspicuous to anyone operating or servicing the  
unit. Be sure the surface is clean and dry and adhere the label.  
1/8” Output  
Pressure  
Tap  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 14  
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The input and/or the capacity of the heater changes with the derate. The tables  
below list inputs and capacities at altitudes from sea level to 10,000 ft (3045M).  
High Altitude  
Capacity Changes  
BTUH Inputs and Capacities by Altitude in the UNITED STATES for Model UDAP and Model UDAS  
Thermal  
Output  
Capacity  
Thermal  
Output  
Capacity  
Thermal  
Output  
Capacity  
Thermal  
Output  
Capacity  
Normal  
Input  
Minimum Normal  
Input Input  
Minimum Normal  
Input Input  
Minimum Normal  
Input Input  
Minimum  
Input  
ALTITUDE  
Feet  
0-2000  
2001-3000  
Meters  
0-610  
611-915  
Size 30  
Size 45  
Size 60  
Size 75  
30000 24600 30000 45000 37350  
28200 23124 28200 42300 35109  
45000 60000 49800 42000 75000 62250  
42300 56400 46812  
52500  
39480 70500 58515 49350  
38640 69000 57270 48300  
3001-4000 916-1220 27600 22632 27600 41400 34362 41400 55200 45816  
4001-5000 1221-1525 27000 22140 27000 40500 33615  
40500 54000 44820 37800 67500 56025  
39600 52800 43824 36960 66000 54780  
38700 51600 42828 36120 64500 53535  
37800 50400 41832 35280 63000 52290  
36900 49200 40836 34440 61500 51045  
36000 48000 39840 33600 60000 49800  
47250  
46200  
45150  
44100  
43050  
42000  
5001-6000 1526-1830 26400 21648 26400 39600 32868  
6001-7000 1831-2135 25800 21156 25800 38700 32121  
7001-8000 2136-2440 25200 20664 25200 37800 31374  
8001-9000 2441-2745 24600 20172 24600 36900 30627  
9001-10000 2746-3045 24000 19680 24000 36000 29880  
Feet  
0-2000  
Meters  
0-610  
Size 100  
Size 125  
Size 150  
Size 175  
105000 88200 73500 120000 100800 84000 150000 124500 105000 175000 145250 122500  
2001-3000  
611-915  
98700 82908 69090 112800 94752  
78960 141000 117030 98700 164500 136535 115150  
77280 138000 114540 96600 161000 133630 112700  
75600 135000 112050 94500 157500 130725 110250  
73920 132000 109560 92400 154000 127820 107800  
72240 129000 107070 90300 150500 124915 105350  
70560 126000 104580 88200 147000 122010 102900  
68880 123000 102090 86100 143500 119105 100450  
67200 120000 99600 84000 140000 116200 98000  
3001-4000 916-1220 96600 81144 67620 110400 92736  
4001-5000 1221-1525 94500 79380 66150 108000 90720  
5001-6000 1526-1830 92400 77616 64680 105600 88704  
6001-7000 1831-2135 90300 75852 63210 103200 86688  
7001-8000 2136-2440 88200 74088 61740 100800 84672  
8001-9000 2441-2745 86100 72324 60270 98400 82656  
9001-10000 2746-3045 84000 70560 58800 96000 80640  
Feet  
Meters  
Size 200  
Size 225  
Size 250  
Size 300  
0-2000  
0-610  
200000 166000 140000 225000 186750 157500 250000 207500 175000 300000 249000 210000  
2001-3000  
611-915 188000 156040 131600 211500 175545 148050 235000 195050 164500 282000 234060 197400  
3001-4000 916-1220 184000 152720 128800 207000 171810 144900 230000 190900 161000 276000 229080 193200  
4001-5000 1221-1525 180000 149400 126000 202500 168075 141750 225000 186750 157500 270000 224100 189000  
5001-6000 1526-1830 176000 146080 123200 198000 164340 138600 220000 182600 154000 264000 219120 184800  
6001-7000 1831-2135 172000 142760 120400 193500 160605 135450 215000 178450 150500 258000 214140 180600  
7001-8000 2136-2440 168000 139440 117600 189000 156870 132300 210000 174300 147000 252000 209160 176400  
8001-9000 2441-2745 164000 136120 114800 184500 153135 129150 205000 170150 143500 246000 204180 172200  
9001-10000 2746-3045 160000 132800 112000 180000 149400 126000 200000 166000 140000 240000 199200 168000  
Feet  
Meters  
Size 350  
Size 400  
0-2000  
0-610  
350000 290500 245000 400000 332000 280000  
2001-3000  
611-915 329000 273070 230300 376000 312080 263200  
3001-4000 916-1220 322000 267260 225400 368000 305440 257600  
4001-5000 1221-1525 315000 261450 220500 360000 298800 252000  
5001-6000 1526-1830 308000 255640 215600 352000 292160 246400  
6001-7000 1831-2135 301000 249830 210700 344000 285520 240800  
7001-8000 2136-2440 294000 244020 205800 336000 278880 235200  
8001-9000 2441-2745 287000 238210 200900 328000 272240 229600  
9001-10000 2746-3045 280000 232400 196000 320000 265600 224000  
BTUH Inputs and Capacities by Altitude in CANADA for Models UDAP and UDAS  
Thermal  
Output  
Capacity  
Thermal  
Output  
Capacity  
Thermal  
Output  
Capacity  
Thermal  
Output  
Capacity  
Normal  
Input  
Minimum Normal  
Input Input  
Minimum Normal  
Input Input  
Minimum Normal  
Input Input  
Minimum  
Input  
ALTITUDE  
Feet  
0-2000  
Meters  
0-610  
Size 30  
30000 24600  
Size 45  
Size 60  
Size 75  
30000 45000 37350  
27000 40500 33615  
Size 125  
45000 60000 49800  
40500 54000 44820  
Size 150  
42000 75000 62250  
37800 67500 56025  
Size 175  
52500  
47250  
2001-4500 611-1373 27000 22140  
Feet  
Meters  
Size 100  
0-2000  
0-610  
105000 88200  
73500 120000 100800 84000 150000 124500 105000 175000 145250 122500  
2001-4500 611-1373 94500 79380  
66150 108000 90720  
75600 135000 113400 94500 157500 132300 110250  
Feet  
Meters  
Size 200  
Size 225  
Size 250 Size 300  
0-2000  
0-610  
200000 166000 140000 225000 186750 157500 250000 207500 175000 300000 249000 210000  
2001-4500 611-1373 180000 151200 126000 202500 170100 141750 225000 189000 157500 270000 226800 189000  
Feet  
Meters  
Size 350  
Size 400  
0-2000  
0-610  
350000 290500 245000 400000 332000 280000  
2001-4500 611-1373 315000 264600 220500 360000 302400 252000  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 15  
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2
This heater has a one-piece TCORE ® burner assembly (patent pending) designed  
13. Burner  
to provide controlled flame stability without lifting or flashback with either natu-  
ral or propane gas.  
The burner can be removed as a unit for inspection or service; see Maintenance  
Section for removal instructions.  
All electrical wiring and connections, including electrical grounding MUST be  
made in accordance with the National Electric Code ANSI/NFPA No. 70 (latest  
edition) or, in Canada, with CSA Standard C22.1. In addition, the installer should  
be aware of any local ordinances or gas company requirements that might apply.  
14. Electrical  
Supply and  
Connections  
CAUTION: Route wires  
so that they do not  
Check the rating plate on the heater for the supply voltage and current require-  
ments. A dedicated line voltage supply with disconnect switch should be run di-  
rectly from the main electrical panel to the heater. All external wiring must be  
within approved conduit and have a minimum temperature rise rating of 60°C.  
Conduit must be run so as not to interfere with the heater access panel. If the  
installation requires a stepdown transformer (Option CG), follow the instructions  
shipped with the option package for attaching the transformer to the heater.  
contact the flue wrapper  
or venter housing.  
CAUTION: If any of the  
original wire as supplied  
with the appliance must  
be replaced, it must be  
replaced with wiring  
material having a  
temperature rating of at  
least 105°C, except for  
limit control, flame  
The electrical supply enters at the rear of the heater (See FIGURE 13). Model  
UDAS includes a built-in disconnect switch (20A @ 115V; 10A @ 230V Rating).  
Model UDAS supply wiring connects to leads located inside a sealed electrical  
box. To maintain the sealing feature of the electrical box, always replace the cover  
plate. Model UDAP supply wiring connects directly to leads on the integrated  
circuit board.  
The circuit board (See FIGURE 12) is located inside on the bottom of the control  
compartment. The circuit board is polarity sensitive. It is advisable to check the  
electrical supply to be certain that the black wire is the “hot” wire and that the  
white wire is the neutral wire. The supply connection made to “L1” on the circuit  
board must be the “hot” wire.  
rollout, and sensor lead  
wires which must be  
150°C. See Hazard  
x
Spark  
Transformer  
Levels, page 2.  
Fuse  
Thermostat  
Connections  
Supply Wiring  
Connections  
NOTE: Circuit  
FIGURE 12 - Supply  
Wiring Connections at  
the Circuit Board (DSI  
Integrated Control  
Module)  
Fan/Blower  
Off  
Delay  
board is polarity  
sensitive; “hot” wire  
Status  
Lights  
must be connected  
to Terminal L1.  
For all models, the terminal strip for 24 volt thermostat connections is located on  
the outside of the cabinet at the back of the heater (See FIGURE 13). Wires from  
the terminal strip are factory wired to the circuit board.  
24V Control Wiring  
Connections  
Use either an optional thermostat available with the heater or a field-supplied 24-  
volt thermostat. Install according to the thermostat manufacturer's instructions, pay-  
ing particular attention to the requirements regarding the location of the thermo-  
stat.  
15.Thermostat  
and  
Connections  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 16  
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Make sure that the heat anticipator setting on the thermostat is 0.6 amps (or in  
accordance with the amperage value noted on the wiring diagram of your heater).  
Make thermostat connections at the terminal strip on the back of the heater. The  
strip has four terminals, R, G, W1, and W2; refer to the wiring diagram.  
FIGURE 13 - Terminal  
Strip for 24-volt wiring  
is on the outside rear  
of the heater  
Rear View - Model UDAP  
Rear View - Model UDAS  
NOTE: The size of heater  
illustrated has a vertical  
terminal strip. Some sizes  
have a horizontal terminal  
strip.  
Terminal  
Strip  
Terminal  
Strip  
R
R
G
G
W1  
W2  
W1  
W2  
Built-in  
Disconnect  
Switch  
Supply  
Wiring  
Entrance  
Supply  
Wiring  
Entrance  
If the heater was ordered with Option CM3, a kit for mounting the thermostat on  
the rear of the heater is shipped separately. Follow the instructions in the option  
package to attach the bracket.  
Unit Mounted  
Thermostat -  
Option CM3  
Select a snap-action thermostat when using the unit mounted thermostat bracket.  
Do not use a mercury switch thermostat because the vibration may cause exces-  
sive unit cycling. Be careful with the thermostat leads; shorting the thermostat  
wires to a metal surface will cause the transformer to fail.  
If the heater was ordered with a multiple heater control option, one thermostat can  
be used to control up to six heaters. The option includes a 40VA transformer that  
replaces the standard transformer in the “master” unit and a relay assembly that  
attaches to the “slave” unit. Option CL31 provides for control of two heaters. If  
control of additional heaters is desired (up to six total), Option CL32 which is the  
relay assembly only must be added to each of the “slave” heaters.  
Multiple Heater  
Control - Option  
CL31 and Option  
CL32  
The option packages are shipped separately and include complete instructions on  
installation and wiring.  
The combustion air proving switch is a pressure sensitive switch that monitors air  
pressure to ensure that proper combustion airflow is available. On Model UDAP,  
the switch is a single pole/normally open device which closes when a negative  
pressure is sensed in the venter housing. On Model UDAS, the switch senses the  
differential pressure between the negative pressure in the venter housing and the  
pressure in the cabinet. (For switch location, see FIGURE 18, page 31.)  
16. Combustion  
Air Proving  
Switch  
(Pressure  
Switch)  
On startup when the heater is cold, the sensing pressure is at the most negative  
level, and as the heater and flue system warm up, the sensing pressure becomes  
less negative. After the system has reached equilibrium (about 20 minutes), the  
sensing pressure levels off.  
If a restriction or excessive flue length or turns cause the sensing pressure to be  
outside the switch setpoint, the pressure switch will function to shutoff the main  
burner. The main burner will remain off until the system has cooled and/or the flue  
system resistance is reduced.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 17  
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The two Tables on the left below list the approximate water column negative pres-  
sure readings and switch setpoints for sea level operating conditions for Model  
UDAP and Model UDAP-CV heaters. The Table on the right lists the approximate  
water column differential pressure readings and switch setpoints for sea level op-  
erating conditions for Model UDAS heaters.  
16. Combustion  
Air Proving  
Switch (cont’d)  
DANGER: Safe operation of this unit requires proper venting  
flow. NEVER bypass combustion air proving switch or attempt  
to operate the unit without the venter running and the proper  
flow in the vent system. Hazardous conditions could result. See  
Hazard Levels, page 2.  
Pressure Switch Settings  
Startup Equilibrium Setpoint Setpoint  
Startup Equilibrium Setpoint Setpoint  
Model  
UDAP  
Label Switch  
Color P/N  
Model  
UDAS  
Label Switch  
Color P/N  
Cold  
Hot  
OFF  
ON  
Cold  
Hot  
OFF  
ON  
Negative Pressure Measured in " w.c.  
Differential Pressure Measured in " w.c.  
30  
45  
60  
75  
100  
125  
1.00  
0.95  
1.00  
1.00  
0.85  
0.75  
0.78  
0.75  
0.78  
0.85  
0.72  
0.60  
0.65  
1.50  
1.60  
1.80  
0.40  
0.40  
0.50  
0.50  
0.50  
0.40  
0.40  
1.10  
1.10  
1.40  
0.58  
0.58  
Green 197030  
Green 197030  
30  
45  
60  
75  
100  
125  
1.00  
1.05  
1.10  
1.10  
0.85  
0.75  
0.78  
0.80  
0.85  
0.85  
0.72  
0.60  
0.60  
1.50  
1.60  
1.80  
0.65  
0.65  
0.65  
0.65  
0.55  
0.45  
0.40  
1.10  
1.10  
1.40  
0.83 Yellow 197028  
0.83 Yellow 197028  
0.83 Yellow 197028  
0.83 Yellow 197028  
0.73 White 196362  
0.68 Orange 196388  
0.68 Orange 196388  
0.68 Orange 196388  
0.58  
0.58  
1.30  
1.30  
1.60  
Green 197030  
0.63  
0.58  
1.30  
1.30  
1.60  
Pink 197032  
Green 197030  
Blue 201158  
Blue 201158  
Red 201159  
150, 175 0.75  
200, 225 2.20  
250, 300 2.30  
350, 400 2.60  
Green 197030 150, 175 0.75  
Blue 201158 200, 225 2.20  
Blue 201158 250, 300 2.30  
Red 201159 350, 400 2.60  
Startup  
Cold  
Equilibrium Setpoint Setpoint  
Model UDAP-CV  
with Opt AV6  
Label  
Color  
Switch  
P/N  
Hot  
OFF  
ON  
Negative Pressure Measured in " w.c.  
30  
45  
60  
75  
100  
1.10  
1.10  
0.92  
0.97  
0.88  
0.84  
0.81  
0.75  
0.78  
0.71  
0.65  
0.50  
0.60  
0.60  
0.55  
0.83 Yellow 197028  
0.68 Orange 196388  
0.78 Lt Blue 197029  
0.78 Lt Blue 197029  
0.73  
White 196362  
All units are equipped with a temperature activated auto reset limit control. The  
control is factory set and is non-adjustable. If the setpoint is reached, the limit  
control will interrupt the electric supply to the gas valve. This safety device pro-  
vides protection in the case of motor failure or lack of airflow due to a restriction at  
the inlet or outlet. (For location, see FIGURE 18, page 31.)  
17. Limit Control  
CAUTION: The auto reset limit control will continue to shut down  
the heater until the cause is corrected. Never bypass the limit  
control; hazardous conditions could result. See Hazard Intensity  
Levels, page 2.  
Sizes 30-125 are equipped with a temperature activated manually reset flame rollout  
switch. The flame rollout switch is located at the top of the burner assembly. It is  
factory set and is non-adjustable. If the setpoint is reached, the flame rollout acts to  
interrupt the electric supply to the gas valve. If the flame rollout switch activates,  
identify and correct the cause before resetting the switch. Refer to the Mainte-  
nance Section for information on probable causes and instructions on resetting the  
flame rollout switch. (For location, see FIGURE 18, page 31.)  
18. Flame  
Rollout  
Switch -  
Sizes 30-125  
only  
DANGER: If the manual reset flame rollout switch activates,  
identify and correct the cause before resetting the switch. Never  
bypass the flame rollout switch; hazardous conditions could result.  
See Hazard Intensity Levels, page 2.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 18  
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All sizes of Model UDAS heaters are equipped with a door switch which prevents  
the heater from operating when the service door panel is open. The service panel  
of a Model UDAS is equipped with a pliable gasket material that fully seals the  
door to provide added protection from building air entering the combustion zone  
of the heater. (For switch location, see FIGURE 18, page 31.)  
19. Door Switch  
- Model  
UDAS only  
This heater is equipped with a direct spark integrated control module (circuit board).  
The module monitors the safety devices and controls the operation of the fan and  
venter motors and the gas valve between heat cycles.  
20. Ignition  
System  
FIGURE 14 – DSI Integrated Control Module (circuit board)  
x
Spark  
Transformer  
Fuse  
Thermostat  
Connections  
Dip Switch  
LED Lights  
Fan/Blower  
Off  
Delay  
Status  
Lights  
Flame Status - Yellow LED Codes  
Steady ON....... Flame is sensed  
Slow Flash ...... Weak flame (current below 1.0  
microamps ±50%)  
Fast Flash ........ Undesired Flame (valve open  
and no call for heat)  
Control Status - Green LED Codes  
Steady ON....... Normal Operation, No call for heat  
Fast Flash ........ Normal Operation, Call for heat  
1 Flash ............ System Lockout, Failed to detect or sustain  
flame  
2 Flashes ......... Pressure Switch Did Not Close within 30  
Seconds of Venter Motor  
Fan/Blower OFF Delay Settings (dip switches)  
SW-1 SW-2 Time  
3 Flashes ......... High Limit or Flame Rollout Switch Open  
4 Flashes ......... Pressure switch is closed before venter  
motor is energized  
Off  
Off  
On  
On  
Off  
On  
Off  
On  
120 seconds (factory setting)  
90 seconds  
160 seconds  
Steady OFF ..... Blown Fuse, No Power, or Defective Board  
180 seconds  
1) Call for Heat - The thermostat calls for heat by energizing the “W” terminal.  
The control checks to see that the limit switch is closed and the pressure switch is  
open. If the limit switch is open, the control responds as defined in the “Abnormal  
Heat Cycle, Limit Switch Operation”. If the pressure switch is closed, the control  
will do four flashes on the green LED and wait indefinitely for the pressure switch  
to open. If the pressure switch is open, the control proceeds to prepurge.  
Normal Heat Cycle  
Operating  
Sequence  
2) Prepurge - The control energizes the venter motor and waits for the pressure  
switch to close. If the pressure switch does not close within 30 seconds of the  
venter motor energizing, the control will do two flashes on the green LED. The  
control will leave the venter motor energized indefinitely as long as the call for  
heat remains and the pressure switch is open.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 19  
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When the pressure switch is proven closed, the control begins the prepurge time.  
If flame is present any time while in prepurge, the prepurge time is restarted. If  
flame is present long enough to cause lockout, the control responds as defined in  
“Fault Modes, Undesired Flame”.  
20. Ignition  
System  
(cont’d)  
Normal Heat  
Cycle Operating  
Sequence (cont’d)  
The control runs the venter motor for a 20 second prepurge time, then proceeds to  
the ignition trial period.  
3) Ignition Trial Period - The control energizes the spark and main gas valve.  
The venter remains energized. If flame is sensed during the first 16 seconds, the  
spark is de-energized and the control proceeds to heat fan/blower on delay. If  
flame has not been sensed during the first 16 seconds, the control de-energizes the  
spark output and keeps the gas valve energized for an additional one second flame  
proving period. If flame is not present after the flame proving period, the control  
de-energizes the gas valve and proceeds with ignition re-tries as specified in “Ab-  
normal Heat Cycle, Ignition Re-try”. If flame is present, the control proceeds to  
the fan/blower on delay.  
4) Fan/Blower On Delay - The control waits for 30 seconds from the time the gas  
valve opened and then energizes the fan/blower motor. The gas valve and venter  
motor remain energized. The control proceeds to steady heat mode.  
5) Steady Heat - Control inputs are continuously monitored to ensure limit and  
pressure switches are closed, flame is established, and the thermostat call for heat  
remains. When the thermostat call for heat is removed, the control de-energizes  
the gas valve and begins post-purge and fan/blower off delay timing.  
6) Post Purge - The venter motor output remains on for a 45 second post-purge  
period after the thermostat is satisfied.  
7) Fan/Blower Off Delay - The fan/blower motor is de-energized after a blower  
off delay as selected by the dip switches. Timing begins when the thermostat is  
satisfied. Delay times are as follows:  
SW1 SW2 Time  
OFF OFF 120 seconds (default when shipped)  
OFF ON  
90 seconds  
OFF 160 seconds  
ON 180 seconds  
ON  
ON  
Interrupted Thermostat Call for Heat - If the thermostat demand for heat is  
removed before the flame is recognized, the control will run the venter motor for  
the post purge period and de-energize all outputs.  
Abnormal Heat  
Cycle Functions  
If the thermostat demand for heat is removed after successful ignition, the control  
will de-energize the gas valve, run the venter motor through post purge, and run  
the fan/blower motor on heat speed for the selected delay off time.  
Ignition Retry - If flame is not established on the first trial for ignition period, the  
control de-energizes the gas valve and the venter motor remains energized for an  
inter-purge period of 10 seconds. The spark and gas valve are then re-energized,  
and the control initiates another trial for ignition.  
If flame is not established on the second trial for ignition, the control de-energizes  
the gas valve, energizes the fan/blower motor on heat speed, and venter motor  
remains energized. The fan/blower motor is shut off after the longest selectable  
fan delay time (180 seconds). When the fan/blower motor de-energizes, the spark  
and gas valve are re-energized and the control initiates another trial for ignition.  
(This fan delay is self-healing feature for an open auxiliary limit switch).  
If flame is not established on the third trial for ignition period, the control de-  
energizes the gas valve, and the venter motor remains energized for an inter-purge  
period of 10 seconds. The control then re-energizes the gas valve and spark and  
initiates another trial for ignition.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 20  
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If flame is not established on the fourth trial for ignition (initial try plus 3 re-tries),  
the control de-energizes the gas valve and goes into lockout. The control goes to  
one flash on the green LED to indicate ignition failure lockout.  
Limit Switch Operation - The limit switch is ignored unless a call for heat is  
present (W energized). If the limit switch is open and a call for heat is present, the  
control de-energizes the gas valve and turns the fan/blower motor on heat speed  
and runs the venter motor.  
When the switch re-closes or the call for heat is lost, the control runs the venter  
motor through post purge and runs the blower/fan motor through the selected fan  
off delay. The control will return to normal operation after fan off delay is com-  
pleted.  
Pressure Switch - If the pressure switch opens before the trial for ignition period,  
the venter motor will run through the pressure switch recognition delay (2 sec-  
onds), the gas valve will be de-energized, and the venter motor will run through  
the postpurge time. The control will re-start the heat cycle at the pressure switch  
proving state if the call for heat still exists.  
Pressure switch opening for less than 2 seconds during the trial for ignition period  
shall not interrupt the heat cycle. (Gas valve will de-energize while the pressure  
switch is open.)  
If the pressure switch opens after a successful ignition, the control will de-energize  
the gas valve. If flame is lost before the end of the 2 second pressure switch recog-  
nition delay, the control will respond to the loss of flame. If the pressure switch  
remains open for 2 seconds and the flame remains, the control de-energizes the gas  
valve, the venter motor runs through post-purge, and the fan/blower motor runs on  
heat speed through the selected fan off delay. When the fan off delay is over, the  
fan/blower motor is de-energized, and a heat cycle is begun if the call for heat still  
exists.  
When the thermostat calls for continuous fan (G) without a call for heat, the fan  
motor is energized after a .25 second delay. NOTE: This brief on delay is to allow  
the “G” terminal to energize slightly before “Y” and an external changeover relay  
to switch from “G” to “W” without causing momentary glitches in the fan/blower  
output. The fan remains energized as long as the call for fan remains without a call  
for heat.  
Continuous Fan  
Operation  
If a call for heat (W) occurs during continuous fan, the fan/blower will de-ener-  
gize.  
A call for fan is ignored while in lockout.  
Undesired Flame - If flame is sensed longer than 20 seconds while the gas valve  
is de-energized, the control shall energize the venter motor and fan/blower motor  
on heat speed. When flame is no longer sensed, the venter motor will run through  
postpurge, and the fan/blower motor will run through the selected heat fan off  
delay time. The control will do a soft lockout, but will still respond to open limit  
and flame. The FLAME (yellow) LED shall flash rapidly when lockout is due to  
undesired flame.  
Fault Modes  
Gas Valve Relay Fault - If the control senses the gas valve as energized for more  
than one second when the control is not attempting to energize the gas valve, or the  
gas valve is sensed as not energized when it is supposed to be energized, then the  
control will lockout with green LED off. The control assumes either the contacts  
of the relay driving the gas valve have welded shut, or the sensing circuit has  
failed. The venter motor is forced off to open the pressure switch to stop gas flow  
unless flame is present.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 21  
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If the gas valve was sensed as closed when it should be open, and has not de-  
energized after the venter motor was shutoff for 15 seconds, then the venter motor  
is re-energized to vent the unburned gas.  
20. Ignition  
System  
(cont’d)  
Fault Modes  
(cont’d)  
Soft Lockout - The control shall not initiate a call for heat or call for continuous  
fan while in lockout. The control will still respond to an open limit and undesired  
flame. Lockout shall automatically reset after one hour. Lockout may be manually  
reset by removing power from the control for more than one second or removing  
the thermostat call for heat for more than one and less than 20 seconds.  
Hard Lockout - If the control detects a fault on the control board, the status LED  
will be de-energized, and the control will lockout as long as the fault remains. A  
hard lockout will automatically reset if the hardware fault clears.  
Lockout  
Power Interruption - During a momentary power interruption or at voltage levels  
below the minimum operating voltage (line voltage or low voltage) the system will  
self-recover without lockout when voltage returns to the operating range.  
Power interruptions of less than 80mS shall not cause the control to change operat-  
ing states. Power interruptions greater than 80mS may cause the control to inter-  
rupt the current operating cycle and re-start.  
The main operating gas valve is powered by the 24-volt control circuit through the  
thermostat and safety controls. The main control valve is of the diaphragm type  
providing regulated gas flow preset at the factory. (For location, see FIGURE 18,  
page 31.)  
21. Gas Valve  
22. Fan Motor  
WARNING: The operating valve is the prime safety shutoff. All  
gas supply lines must be free of dirt or scale before connecting  
the unit to ensure positive closure. See Hazard Levels, page 2.  
The fan motor is equipped with thermal overload protection of the automatic reset  
type. Should the motor refuse to run, it may be because of improper current char-  
acteristics. Make certain that the correct voltage is available at the motor.  
NOTE: If the unit is equipped with an optional totally enclosed motor or optional  
voltage, the horsepower may be larger than the standard motor. Refer to the motor  
nameplate to verify horsepower.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 22  
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23. Wiring Diagrams  
FIGURE 15A - Typical Wiring Diagram for Model UDAP or Model UDAS, Single Stage  
30 VA  
LINE/1/60  
SYSTEM TRANSFORMER  
FACTORY WIRING  
Y
W
R
FIELD WIRING  
R
OPTIONAL FACTORY  
WIRING  
G
G
WIRE NUT  
BR  
GRD  
SCREW  
BK  
G
W1  
R
SW1  
G
W
R
SEC  
COM  
L1  
NEUTRAL NEUTRAL  
L1  
P3-1  
Y
PR  
Y
W
NEUTRAL  
P3-2  
G
FAN MOTOR  
BK  
BK  
W
EAC/BLO  
P3-3  
W
G
DOOR INTERLOCK  
(UDAS ONLY)  
P3-4  
P3-5  
P1-8  
P1-3  
R
R
R
C
CAPACITOR  
(SEE NOTE #6)  
LED FLASH CODES  
GREEN LED  
STEADY ON NORMAL OPERATION NO CALL FOR HEAT  
FAST FLASH NORMAL OPERATION CALL FOR HEAT  
LIMIT CONTROL  
W2  
R
R
1 FLASH  
2 FLASH  
IN LOCKOUT FROM FAILED IGNITIONS OR FLAME LOSSES  
PRESSURE SWITCH DOES NOT CLOSE WITHIN 30 SECONDS  
OF VENTER ENERGIZED  
R
R
3 FLASH  
4 FLASH  
LIMIT SWITCH OR ROLLOUT SWITCH OPEN  
FLAME ROLLOUT  
(MODELS 30-125 ONLY)  
PRESSURE SWITCH IS CLOSED BEFORE VENTER IS  
ENERGIZED  
STEADY OFF INTERNAL CONTROL FAULT OR NO POWER  
YELLOW LED  
P1-6  
P1-5  
P1-4  
P1-2  
P1-7  
P1-9  
Y
STEADY ON FLAME SENSED  
PRESSURE SWITCH  
SLOW FLASH WEAK FLAME  
Y
Y
FAST FLASH UNDESIRED FLAME (VALVE OPEN & NO CALL FOR HEAT)  
BK  
BL  
FAN OFF DELAY  
TEST  
IND  
S W 1  
VENTER  
MOTOR  
TIME  
1
2
GAS VALVE  
90  
OFF  
OFF  
ON  
ON  
FLAME  
OK  
BL  
BR  
W
W
BK  
NEUTRAL  
LED  
LED  
120  
160  
180  
OFF  
OFF  
ON  
G
Y
G
FLAME  
R
ON  
ELECTRODE  
SPARK  
CAPACITOR  
(SEE NOTE #7)  
BR  
TRANSFORMER  
DSI CONTROL  
FLAME  
GROUND  
SPARK GAP  
OPERATING SEQUENCE  
FIELD CONTROL WIRING  
1. SET THERMOSTAT AT LOWEST SETTING, (FAN SWITCH  
AT "AUTO" POSITION, OPTION CL2 ONLY).  
2. TURN ON MANUAL GAS VALVE.  
3. TURN ON POWER TO UNIT.  
4. SET THERMOSTAT AT DESIRED SETTING.  
5. THERMOSTAT CALLS FOR HEAT, ENERGIZING THE VENTER MOTOR.  
6. VENTER PRESSURE SWITCH CLOSES, FIRING UNIT AT FULL RATE.  
7. BURNER FLAME IS SENSED, AND IN 30 SECONDS THE FAN  
TOTAL WIRE  
LENGTH  
DISTANCE FROM  
UNIT TO CONTROL  
MIN. RECOMMENDED  
WIRE GAUGE  
#18 GA. WIRE  
#16 GA. WIRE  
#14 GA. WIRE  
150'  
250'  
350'  
75'  
125'  
175'  
MOTOR IS ENERGIZED.  
8. IF THE FLAME IS EXTINGUISHED DURING MAIN BURNER OPERATION,  
THE INTEGRATED CONTROL SYSTEM CLOSES THE MAIN VALVE AND  
MUST BE RESET BY INTERRUPTING POWER TO THE CONTROL CIRCUIT  
(SEE LIGHTING INSTRUCTIONS).  
WIRING CODE  
BLACK - BK  
BROWN - BR  
RED - R  
9. SET FAN SWITCH AT "ON" POSITION FOR CONTINUOUS FAN OPERATION, OPTION CL2 ONLY.  
ORANGE - O  
YELLOW - Y  
GREEN - G  
BLUE - BL  
PURPLE - PR  
WHITE - W  
NOTES  
1. THE FOLLOWING CONTROLS ARE FIELD INSTALLED OPTIONS: THERMOSTAT  
2. DOTTED WIRING INSTALLED BY OTHERS.  
3. CAUTION: IF ANY OF THE ORIGINAL WIRING AS SUPPLIED WITH THE  
APPLIANCE MUST BE REPLACED, IT MUST BE REPLACED WITH WIRING MATERIAL  
HAVING A TEMPERATURE RATING OF AT LEAST 105° C. EXCEPT FOR SENSOR  
LEAD WIRE, FLAME ROLLOUT AND LIMIT WIRING WHICH MUST BE 150° C.  
4. USE 18 GA. WIRE FOR ALL WIRING ON THE UNIT.  
5. LINE AND FAN MOTOR BRANCH WIRE SIZES SHOULD BE OF A SIZE TO PREVENT  
VOLTAGE DROPS BEYOND 5% OF SUPPLY LINE VOLTAGE.  
6. CAPACITOR IS REMOTE MOUNTED AND INCLUDED ONLY ON 115V MODELS  
150-400 AND 208/230V MODELS 100-400.  
7. CAPACITOR IS REMOTE MOUNTED AND INCLUDED ONLY ON MODELS 150 - 400.  
8. SET THERMOSTAT ANTICIPATOR AT 0.6 AMPS.  
UDAP & UDAS SERIES  
WD# 185139 REV #1 AG1  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 23  
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23. Wiring Diagrams (cont’d)  
FIGURE 15B - Typical Wiring Diagram for Model UDAP or Model UDAS, Single Stage with  
Optional Air Recirculation  
30 VA  
LINE/1/60  
SYSTEM TRANSFORMER  
FACTORY WIRING  
Y
FIELD WIRING  
R
OPTIONAL FACTORY  
G
WIRING  
G
WIRE NUT  
BR  
GRD  
SCREW  
BK  
SW1  
G
W1  
G
SEC  
COM  
L1  
NEUTRAL NEUTRAL  
L1  
P3-1  
P3-2  
P3-3  
P3-4  
P3-5  
P1-8  
P1-3  
PR  
Y
Y
G
W
R
C
W
NEUTRAL  
W1  
FAN MOTOR  
BK  
BK  
W
W2  
EAC/BLO  
G
DOOR INTERLOCK  
(UDAS ONLY)  
R
R
R
CAPACITOR  
(SEE NOTE #6)  
RH  
RC  
LED FLASH CODES  
GREEN LED  
STEADY ON NORMAL OPERATION NO CALL FOR HEAT  
FAST FLASH NORMAL OPERATION CALL FOR HEAT  
LIMIT CONTROL  
W2  
R
R
1 FLASH  
2 FLASH  
IN LOCKOUT FROM FAILED IGNITIONS OR FLAME LOSSES  
PRESSURE SWITCH DOES NOT CLOSE WITHIN 30 SECONDS  
OF VENTER ENERGIZED  
R
R
3 FLASH  
4 FLASH  
LIMIT SWITCH OR ROLLOUT SWITCH OPEN  
FLAME ROLLOUT  
(MODELS 30-125 ONLY)  
PRESSURE SWITCH IS CLOSED BEFORE VENTER IS  
ENERGIZED  
P1-6  
P1-5  
P1-4  
P1-2  
P1-7  
P1-9  
STEADY OFF INTERNAL CONTROL FAULT OR NO POWER  
YELLOW LED  
Y
STEADY ON FLAME SENSED  
PRESSURE SWITCH  
Y
Y
SLOW FLASH WEAK FLAME  
FAST FLASH UNDESIRED FLAME (VALVE OPEN & NO CALL FOR HEAT)  
BK  
W
BL  
FAN OFF DELAY  
TIME  
TEST  
IND  
VENTER  
MOTOR  
GAS VALVE  
90  
120  
160  
180  
OFF  
OFF  
ON  
ON  
FLAME  
OK  
BL  
BR  
W
BK  
NEUTRAL  
LED  
LED  
OFF  
OFF  
ON  
G
Y
G
FLAME  
R
ON  
ELECTRODE  
SPARK  
CAPACITOR  
(SEE NOTE #7)  
TRANSFORMER  
BR  
DSI CONTROL  
FLAME  
GROUND  
SPARK GAP  
OPERATING SEQUENCE  
FIELD CONTROL WIRING  
1. SET THERMOSTAT AT LOWEST SETTING, FAN SWITCH AT "AUTO" POSITION.  
2. TURN ON MANUAL GAS VALVE.  
TOTAL WIRE  
LENGTH  
DISTANCE FROM  
UNIT TO CONTROL  
MIN. RECOMMENDED  
3. TURN ON POWER TO UNIT.  
WIRE GAUGE  
4. SET THERMOSTAT AT DESIRED SETTING.  
5. LOW STAGE OF THERMOSTAT CALLS FOR HEAT, ENERGIZING THE FAN MOTOR.  
6. HIGH STAGE OF THERMOSTAT CALLS FOR HEAT, ENERGIZING THE VENTER MOTOR.  
7. VENTER PRESSURE SWITCH CLOSES, FIRING UNIT AT FULL RATE.  
8. SET FAN SWITCH AT "ON" POSITION FOR CONTINUOUS FAN OPERATION.  
#18 GA. WIRE  
#16 GA. WIRE  
#14 GA. WIRE  
150'  
250'  
350'  
75'  
125'  
175'  
9. IF THE FLAME IS EXTINGUISHED DURING MAIN BURNER OPERATION,  
THE INTEGRATED CONTROL SYSTEM CLOSES THE MAIN VALVE AND  
MUST BE RESET BY INTERRUPTING POWER TO THE CONTROL CIRCUIT  
(SEE LIGHTING INSTRUCTIONS).  
WIRING CODE  
BLACK - BK  
BROWN - BR  
RED - R  
ORANGE - O  
YELLOW - Y  
GREEN - G  
BLUE - BL  
NOTES  
1. THE FOLLOWING CONTROLS ARE FIELD INSTALLED OPTIONS: THERMOSTAT  
2. DOTTED WIRING INSTALLED BY OTHERS.  
3. CAUTION: IF ANY OF THE ORIGINAL WIRING AS SUPPLIED WITH THE  
APPLIANCE MUST BE REPLACED, IT MUST BE REPLACED WITH WIRING MATERIAL  
HAVING A TEMPERATURE RATING OF AT LEAST 105° C. EXCEPT FOR SENSOR  
LEAD WIRE, FLAME ROLLOUT AND LIMIT WIRING WHICH MUST BE 150° C.  
4. USE 18 GA. WIRE FOR ALL WIRING ON THE UNIT.  
PURPLE - PR  
WHITE - W  
5. LINE AND FAN MOTOR BRANCH WIRE SIZES SHOULD BE OF A SIZE TO PREVENT  
VOLTAGE DROPS BEYOND 5% OF SUPPLY LINE VOLTAGE.  
6. CAPACITOR IS REMOTE MOUNTED AND INCLUDED ONLY ON 115V MODELS  
150-400 AND 208/230V MODELS 100-400.  
7. CAPACITOR IS REMOTE MOUNTED AND INCLUDED ONLY ON MODELS 150 - 400.  
8. SET THERMOSTAT SECOND STAGE ANTICIPATOR AT 0.6 AMPS. AND FIRST  
STAGE ANTICIPATOR AT MINIMUM.  
UDAP & UDAS SERIES  
WD# 185306 REV#2  
9. JUMPER THERMOSTAT TERMINALS G TO W1 AND RH TO RC IF FAN CONTROL FROM  
THERMOSTAT FAN SWITCH IS DESIRED.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 24  
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FIGURE 15C - Typical Wiring Diagram for Model UDAP or Model UDAS, Two Stage Gas Valve  
W1  
30 VA  
LINE/1/60  
SYSTEM TRANSFORMER  
FACTORY WIRING  
Y
FIELD WIRING  
R
R
OPTIONAL FACTORY  
WIRING  
G
G
WIRE NUT  
BR  
GRD  
SCREW  
BK  
W2  
G
G
W1  
R
SW1  
SEC  
Y
COM  
L1  
NEUTRAL NEUTRAL  
L1  
P3-1  
P3-2  
P3-3  
PR  
Y
W
NEUTRAL  
G
W
R
FAN MOTOR  
BK  
BK  
W
W1  
EAC/BLO  
G
DOOR INTERLOCK  
(UDAS ONLY)  
P3-4  
P3-5  
P1-8  
P1-3  
R
R
CAPACITOR  
(SEE NOTE #6)  
RH  
RC  
LED FLASH CODES  
C
GREEN LED  
STEADY ON NORMAL OPERATION NO CALL FOR HEAT  
FAST FLASH NORMAL OPERATION CALL FOR HEAT  
LIMIT CONTROL  
R
R
W2  
1 FLASH  
2 FLASH  
IN LOCKOUT FROM FAILED IGNITIONS OR FLAME  
W2  
PRESSURE SWITCH DOES NOT CLOSE WITHIN  
30 SECONDS OF VENTER ENERGIZED  
O
R
R
3 FLASH  
4 FLASH  
LIMIT SWITCH OR ROLLOUT SWITCH OPEN  
FLAME ROLLOUT  
(MODELS 30-125 ONLY)  
PRESSURE SWITCH IS CLOSED BEFORE  
VENTER IS ENERGIZED  
P1-6  
P1-5  
P1-4  
P1-2  
P1-7  
P1-9  
STEADY OFF INTERNAL CONTROL FAULT OR NO POWER  
YELLOW LED  
Y
ALT.  
HONEYWELL  
TWO STAGE  
GAS VALVE  
STEADY ON FLAME SENSED  
SLOW FLASH WEAK FLAME  
PRESSURE SWITCH  
HONEYWELL  
TWO STAGE  
GAS VALVE  
Y
Y
FAST FLASH UNDESIRED FLAME (VALVE OPEN & NO CALL  
FOR HEAT)  
BK  
W
BL  
BL  
FAN OFF DELAY  
TEST  
MV  
C
LO  
C
IND  
S W  
VENTER  
MOTOR  
TIME  
2
1
90  
OFF  
ON  
FLAME  
OK  
BR  
W
BK  
BR  
NEUTRAL  
LED  
LED  
120  
160  
180  
OFF  
ON  
OFF  
OFF  
ON  
G
Y
G
FLAME  
R
ON  
ELECTRODE  
SPARK  
CAPACITOR  
(SEE NOTE #7)  
TRANSFORMER  
O
O
BR  
HI  
HI  
DSI CONTROL  
FLAME  
GROUND  
SPARK GAP  
OPERATING SEQUENCE  
1. SET THERMOSTAT AT LOWEST SETTING, (FAN SWITCH AT "AUTO" POSITION, OPTION CL18 ONLY).  
2. TURN ON MANUAL GAS VALVE.  
FIELD CONTROL WIRING  
3. TURN ON POWER TO UNIT.  
TOTAL WIRE  
LENGTH  
4. SET THERMOSTAT AT DESIRED SETTING.  
DISTANCE FROM  
UNIT TO CONTROL  
MIN. RECOMMENDED  
5. LOW STAGE OF THERMOSTAT CALLS FOR HEAT, ENERGIZING THE VENTER MOTOR.  
6. VENTER PRESSURE SWITCH CLOSES, FIRING UNIT AT LOW RATE.  
WIRE GUAGE  
#18 GA. WIRE  
#16 GA. WIRE  
#14 GA. WIRE  
150'  
250'  
350'  
75'  
125'  
175'  
7. BURNER FLAME IS SENSED, AND IN 30 SECONDS THE FAN  
MOTOR IS ENERGIZED.  
8. HIGH STAGE OF THERMOSTAT CALLS FOR HEAT, FIRING UNIT AT FULL RATE.  
9. SET FAN SWITCH AT "ON" POSITION FOR CONTINUOUS FAN OPERATION, OPTION CL18 ONLY.  
10. IF THE FLAME IS EXTINGUISHED DURING MAIN BURNER OPERATION,  
THE INTEGRATED CONTROL SYSTEM CLOSES THE MAIN VALVE AND  
MUST BE RESET BY INTERRUPTING POWER TO THE CONTROL CIRCUIT  
(SEE LIGHTING INSTRUCTIONS).  
WIRING CODE  
BLACK - BK  
BROWN - BR  
RED - R  
ORANGE - O  
YELLOW - Y  
GREEN - G  
BLUE - BL  
NOTES  
1. THE FOLLOWING CONTROLS ARE FIELD INSTALLED OPTIONS: THERMOSTAT  
2. DOTTED WIRING INSTALLED BY OTHERS.  
3. CAUTION: IF ANY OF THE ORIGINAL WIRING AS SUPPLIED WITH THE  
APPLIANCE MUST BE REPLACED, IT MUST BE REPLACED WITH WIRING MATERIAL  
HAVING A TEMPERATURE RATING OF AT LEAST 105° C. EXCEPT FOR SENSOR  
LEAD WIRE, FLAME ROLLOUT AND LIMIT WIRING WHICH MUST BE 150° C.  
4. USE 18 GA. WIRE FOR ALL WIRING ON THE UNIT.  
5. LINE AND FAN MOTOR BRANCH WIRE SIZES SHOULD BE OF A SIZE TO PREVENT  
VOLTAGE DROPS BEYOND 5% OF SUPPLY LINE VOLTAGE.  
PURPLE - PR  
WHITE - W  
6. CAPACITOR IS REMOTE MOUNTED AND INCLUDED ONLY ON 115V MODELS  
150-400 AND 208/230V MODELS 100-400.  
7. CAPACITOR IS REMOTE MOUNTED AND INCLUDED ONLY ON MODELS 150 - 400.  
8. SET THERMOSTAT FIRST STAGE ANTICIPATOR AT 0.6 AMPS AND  
SECOND STAGE ANTICIPATOR AT 0.2 AMPS.  
UDAP & UDAS SERIES  
WD# 185244 REV #3 AG2  
9. JUMPER THERMOSTAT TERMINALS RH TO RC.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 25  
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o Check to be sure that all screws used to hold shipping brackets were re-  
24. Check  
Installation  
and Startup  
installed in the heater cabinet.  
o Check suspension. Unit must be secure and level.  
o Check clearances from combustibles. Requirements are in Paragraph 8.  
o Check vent system to be sure that it is installed according to the instructions  
in the appropriate Vent Installation Manual as listed in Paragraph 1.  
o Check piping for leaks and proper gas line pressure. Bleed gas lines of  
Check the  
installation prior  
to startup:  
trapped air. See Paragraph 12.  
o Check electrical wiring. Be sure all wire gauges are as recommended. A  
service disconnect switch should be used. Verify that fusing or circuit break-  
ers are adequate for the load use.  
o Check polarity. Verify that line voltage exists between the black “L1” and  
earth ground.  
o If installed in California, verify that California Warning Label is displayed  
Heater  
Startup:  
WARNINGS: For your safety, read before operating. If you do  
not follow these instructions exactly, a fire or explosion may  
result causing property damage, personal injury, or loss of life.  
• This appliance does not have a pilot. It is equipped with an ignition  
device which automatically lights the burner. Do not try to light the  
burner by hand.  
• Before operating, smell all around the appliance area for gas. Be  
sure to smell next to the floor because some gas is heavier than air  
and will settle on the floor.  
WHAT TO DO IF YOU SMELL GAS  
• Do not try to light any appliance.  
• Do not touch any electrical switch; do not use any phone in your  
building.  
• Immediately call your gas supplier from a neighbor's phone.  
Follow the gas supplier's instructions.  
• If you cannot reach your gas supplier, call your fire department.  
• Use only your hand to turn the gas control ON/OFF knob on the  
gas valve. Never use tools. If the valve ON/OFF knob will not turn  
by hand, do not try to repair it. Call a qualified service technician.  
Force or attempted repair may result in a fire or explosion.  
• Should overheating occur, or the gas supply fail to shut off, turn off  
the manual gas valve to the appliance before shutting off the  
electrical supply.  
• Do not use this appliance if any part has been under water. Imme-  
diately call a qualified service technician to inspect the appliance  
and to replace any part of the control system and any gas control  
which has been under water.  
1. Set thermostat at lowest setting.  
Operating  
Instructions and  
Operating Sequence  
2. Turn off all electric power to the appliance.  
3. This appliance is equipped with an ignition device which automatically lights  
the burner. Do not try to light the burner by hand. Open the access door and  
locate the gas control (ON/OFF) knob on the gas valve. (See FIGURE 16.)  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 26  
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4. Turn the gas control knob clockwise to "OFF".  
FIGURE 16 - Gas Valve  
ON/OFF Control Knob  
5. Wait five (5) minutes to clear out any gas. Then smell for gas, including near  
the floor. If you smell gas, STOP! and follow the steps in the WARNINGS  
printed above or on the Operating Label on the heater. If you do not smell  
gas, proceed to the next step.  
Top View  
6. Turn the gas control knob counterclockwise to "ON".  
7. Close the access door.  
8. Turn on the electric power to the heater.  
9. Set the thermostat to the desired setting.  
Gas Control  
Knob  
(shown in the  
ON position)  
Side View  
NOTE: If the appliance does not operate, follow the instructions "To Turn Off  
Gas to Appliance" printed below (and on the Operating Label on the heater) and  
call your service technician.  
Gas  
Flow  
Gas  
Flow  
10. Thermostat calls for heat, energizing the venter motor.  
11. Venter pressure switch closes, firing the unit.  
12. Burner flame is sensed and in 30 seconds after the gas valve is energized, the  
fan motor is energized.  
13. If the flame is extinguished during the main burner operation, the integrated  
control system closes the main valve and must be reset by interrupting  
power to the control circuit. (See lighting instructions on the heater.).  
TO TURN OFF GAS TO THE APPLIANCE  
1) Set thermostat to lowest setting  
2) If service is to be performed, turn off all electric power to the appliance.  
3) Open the access door.  
4) Turn the gas control knob clockwise to "OFF". Do not force.  
5) Close the access door.  
o Vent System Testing Procedure - Model UDAP  
Check installation  
after startup:  
1. Seal any unused openings in the venting system.  
2. Inspect the venting system for proper size and horizontal pitch, as required  
in the National Fuel Gas Code, ANSI Z223.1 or CAN/CGA B149.1 and  
B149.2, Installation Code for Gas Burning Appliances and Equipment, and  
the venting installation manual. Determine that there is no blockage or  
restriction, leakage, corrosion or other deficiencies that could cause an  
unsafe condition.  
3. In so far as practical, close all building doors and windows and all doors  
between the space where the heater is and other spaces of the building. Turn  
on clothes dryers and exhaust fans, such as range hoods and bathroom  
exhausts, so they shall operate at maximum speed. Do not operate a sum-  
mer exhaust fan. Close fireplace dampers.  
4. Light the heater following the lighting instructions. Adjust the thermostat  
for continued operation. Verify that combustion products are venting  
properly. After determining that the heater vents properly, return doors,  
windows, exhaust fans, and fireplace dampers to their previous conditions.  
If improper venting is observed, the venting system must be corrected.  
o With the unit in operation, measure valve outlet gas pressure. If operated at  
high altitude, adjust outlet gas pressure for altitude.  
See information and instructions in Paragraph 12.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 27  
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o Turn the unit off and on, pausing two minutes between each cycle. Observe  
24. Startup  
(cont’d)  
for smooth ignition.  
o Place the "Owner's Envelope" containing the Limited Warranty, this booklet,  
and any control or optional information in an accessible location near the  
heater. Follow the instructions on the envelope.  
DANGER: The gas burner in this gas-fired equipment is designed and equipped to provide safe  
controlled complete combustion. However, if the installation does not permit the burner to  
receive the proper supply of combustion air, complete combustion may not occur. The result is  
incomplete combustion which produces carbon monoxide, a poisonous gas that can cause death.  
Safe operation of indirect-fired gas burning equipment requires a properly operating vent system  
that vents all flue products to the outside atmosphere. FAILURE TO PROVIDE PROPER  
VENTING WILL RESULT IN A HEALTH HAZARD WHICH COULD CAUSE SERIOUS  
PERSONAL INJURY OR DEATH.  
Always comply with the combustion air requirements in the installation codes and in Paragraph  
9. Combustion air at the burner should be regulated only by manufacturer-provided equipment.  
NEVER RESTRICT OR OTHERWISE ALTER THE SUPPLY OF COMBUSTION AIR TO  
ANY HEATER. Model UDAP units installed in a confined space must be supplied with air for  
combustion as required by Code and in Paragraph 9 of this heater installation manual.  
MAINTAIN THE VENT OR VENT/COMBUSTION AIR SYSTEM IN STRUCTURALLY  
SOUND AND PROPER OPERATING CONDITION.  
WARNING: If you turn off the power supply, turn off the gas. See Hazard  
Levels, page 2.  
MAINTENANCE  
AND SERVICE  
The material contained in the MAINTENANCE AND SERVICE Section of this  
manual is designed to aid a qualified service person in maintaining and servicing  
this equipment. This heater will operate with a minimum of maintenance. To en-  
sure long life and satisfactory performance, a heater that is operated under normal  
conditions should be inspected and cleaned at the start of each heating season. If  
the heater is operating in an area where an unusual amount of dust or soot or other  
impurities are present in the air, more frequent maintenance is recommended.  
When any service is completed, be careful to reassemble correctly to ensure that  
no unsafe conditions are created. When re-lighting, always follow the lighting  
instructions on the heater.  
Maintenance Schedule - The following procedures should be carried out at least  
annually (See FIGURE 18 and Paragraphs 26-39.):  
25. Maintenance  
Schedule  
• Clean all dirt, lint, and grease from the combustion air opening (UDAP) and  
venter assembly.  
• Clean all dirt, lint, and grease from the fan blade, fan guard, and motor.  
• Check the heat exchanger both internally and externally.  
NOTE: If replacement  
parts are required,  
use only factory-authorized  
parts.  
• Check the burner for scale, dust, or lint accumulation. Clean if needed.  
• Check the vent or vent/combustion air system for soundness. Clean openings.  
Replace any parts that do not appear sound.  
• Check the wiring for any damaged wire. Replace damaged wiring. (See Para-  
graph 14 for replacement wiring requirements.)  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 28  
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2
This heater is equipped with a TCORE ® heat exchanger (patent pending).  
26. Heat  
Exchanger  
Maintenance  
Remove any external dirt or dust accumulation. Visually check the heat exchanger  
for cracks and holes. If a crack or hole is observed, replace the heat exchanger.  
NOTE: Inspection of the lower portion of the heat exchanger is done with the  
burner removed. See the Burner Service section below for information on inspect-  
ing the lower portion of the heat exchanger.  
2
This heater is equipped with a TCORE ® burner (patent pending).  
27. Burner  
Inspect the burner/control compartment annually to determine if cleaning is nec-  
essary. If there is an accumulation of dirt, dust, and/or lint, clean the compartment  
and follow the instructions below to remove and clean the burner.  
Maintenance  
CAUTION: Use of eye protection is recommended.  
Burner Removal  
Instructions (Refer  
to FIGURE 17.)  
1. Outside the cabinet, shut the gas supply off at the manual valve ahead of the  
union.  
2. Turn off electric supply.  
3. Disconnect the gas supply at the union outside of the cabinet.  
4. Remove the access panel.  
5. Disconnect the Gas Train and Move Out of the Way - At the gas valve,  
mark and disconnect the wires. Carefully remove the burner orifice and  
orifice adapter locking nut. Slide the orifice adapter out through the bracket  
on the burner pushing the gas train to the right. This will move the gas train  
out of the way.  
6. Move the Control Assembly - Remove the two screws holding the control  
assembly bracket. Being careful not to disconnect any wires, slide the control  
assembly to the right.  
7. Remove Secondary Air Baffles (Sizes 60-400 only) - Vertical along the right  
side of the burner, locate the flat plate(s) identified as the secondary air  
baffle(s). The quantity of baffles could be one to four depending on heater  
FIGURE 17 - Burner  
Removal (UDAP  
illustrated; same process  
for both UDAP and UDAS)  
Burner Body Support (at least two per unit) - Remove screw attaching  
to secondary air shield. Support remains attached to burner.  
Secondary Air Shield  
Burner  
Orifice  
Venturi Tube  
Slide right; rotate  
inward; pull out  
Gas Valve  
Disconnect gas train at  
orifice and outside the  
heater; slide to the right.  
Slide Right  
Secondary Air Baffle  
Orifice Adapter Locking Nut  
Control Bracket Screws -  
Loosen bracket; slide right.  
(Qty varies per size.)  
Mark locations before removing.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 29  
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size. Each baffle is held in place by one screw. For re-assembly, on the  
secondary air shield, mark the location (top and bottom) of each baffle.  
Remove all baffles.  
27. Burner  
Maintenance  
(cont’d)  
Burner Removal  
(cont’d)  
8. Remove Burner Assembly  
a) Locate the burner body supports. Depending on the size, the burner will  
have two or more supports. At each support, remove the one screw that  
attaches it to the secondary air shield  
b) Holding the venturi tube, slide the entire burner assembly slightly to the  
right to disengage the burner from the supports on the left. Then rotate  
the open end of the venturi tube inward toward the heater. Carefully pull  
the burner assembly out of the cabinet.  
With the burner assembly removed, shine a flashlight on the burner ribbons. Look  
for carbon buildup, scale, dust, lint, and/or anything that might restrict flow through  
the spaces between the burner ribbons. Holding the burner assembly so that any  
foreign material will fall away from the burner, use a stiff bristle brush to loosen  
and remove any foreign material(s). If the burner is excessively dirty, remove one  
of the burner end caps. Remove the four screws that hold the end cap to the burner  
housing. Lightly tap the end cap to remove it.  
Inspect and Clean the  
Burner  
Clean all foreign material from the burner and venturi. After the burner is thor-  
oughly clean, replace the end cap making certain that it is tight against the burner  
housing. NOTE: If any of the burner components are damaged or deteriorated,  
replace the burner assembly.  
Inspect the Lower Portion of the Heat Exchanger (with burner  
assembly removed)  
At the burner flame entrance of each tube, shine a bright light into each heat  
exchanger section. With the light shining into the heat exchanger, observe the  
outside for visible light. Repeat this procedure with each heat exchanger section.  
If any light is observed, replace the heat exchanger.  
Instructions to Re-Install the Burner (Refer to FIGURE 17)  
1. Attach the Burner Assembly - Holding the venturi tube, slide the entire  
burner assembly into position. Align the supports on the left side with the  
slots in the burner shield; sliding the supports into the slots. On the right, re-  
attach each burner body support to the secondary air shield.  
2. Attach the Secondary Air Baffles (Sizes 60-400 only) - Re-attach the  
secondary air baffles as marked. Baffles may be different sizes and each  
must be attached in the correct location.  
Re-Install the Burner  
3. Attach the Control Assembly - Carefully slide the control assembly into  
position. Re-attach with the same screws. Check to be sure all wire connec-  
tions are secure.  
4. Attach the Gas Train - Slide the gas train so that the orifice adapter is  
through the bracket. Fasten the gas train to the bracket with the locking nut.  
Install the gas orifice. Re-connect the wires to the gas valve.  
5. Close the access panel.  
6. Reconnect the gas supply at the union outside of the cabinet. Leak test the  
connection with leak detecting solution.  
7. Turn on the electric and the gas. Check for proper operation.  
Burner orifice usually only needs to be replaced when installing a gas conversion  
kit. If ordering a replacement orifice only, give BTUH content and specific grav-  
ity of gas, as well as the model and serial number of the unit. When removing or  
replacing the burner orifice be careful not to damage the venturi tube and/or the  
bracket.  
28. Burner  
Orifice  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 30  
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FIGURE 18 - Location of Controls  
Venter Motor (Size 30-75  
illustrated. Venter motor  
is in the same location for  
all models, but appear-  
ance is different.)  
Flame Sensor  
Flame Rollout Switch  
(Sizes 30-125)  
Pressure Switch  
- Sizes 30-125  
High Temperature  
Limit Control  
Model UDAS has a  
collar for combustion  
air pipe (not illustrated)  
Interlock Door  
Switch - UDAS only  
Fan  
Motor  
Gas Valve  
Terminal  
Board (24V)  
Disconnect Switch  
- UDAS only  
Electrical Box - UDAS only  
Remove cover to connect  
supply and access  
Ignitor  
Transformer  
disconnect switch wires .  
Always replace cover.  
Control Panel Assy  
located on the  
Control Compartment  
Bottom  
Transformer  
Pressure Switch  
(Sizes 150-400)  
Sizes 30-125  
Sizes 150-400  
Venter Motor  
Capacitor  
Circuit Board  
(DSI Integrated  
Control Module)  
Circuit Board  
(DSI Integrated  
Control Module)  
Optional  
Fan Motor  
Capacitor  
Fan Motor  
Capacitor  
DSI Integrated Control Module (circuit board) - See FIGURE 19. The module  
monitors the operation of the heater including ignition. The only replaceable com-  
ponent is the 3 amp Type ATC or ATO fuse. If the fuse is blown, the problem is  
most likely an external overload. Correct the problem and replace the fuse.  
29. Ignition  
System  
Do not attempt to disassemble the control module. However, each heating season  
check the lead wires for insulation deterioration and good connections.  
Proper operation of the direct spark ignition system requires a minimum flame  
signal of 1.0 microamps as measured by a microampmeter.  
For further information and check out procedure on the direct spark ignition sys-  
tem, refer to Paragraph 20 and the Troubleshooting Flow Chart in Paragraph 40.  
FIGURE 19 - DSI  
Integrated Control Module  
(Circuit Board)  
Only replaceable part  
is a Type ATC or ATO 3  
amp fuse (Color Code  
Violet), P/N 201685  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 31  
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Ignitor - Refer to FIGURE 18 and locate the ignitor. Disconnect the wire; re-  
move the screw and the ignitor. Clean the ignitor assembly with an emery cloth.  
29. Ignition  
System  
Spark gap must be maintained to 1/8". See FIGURE 20.  
FIGURE 20 - Ignitor  
showing required  
Spark Gap  
(cont’d)  
1/8 inch  
(3.2mm)  
Ignitor  
measurement  
IMPORTANT: When re-assembling, the brown ground wire must remain attached  
to the ignitor.  
CAUTION: Due to high voltage on the spark wire and electrode,  
do not touch when energized. See Hazard Levels, page 2.  
Flame Sensor - Refer to FIGURE 18 and locate the flame sensor. Disconnect the  
wire; remove the screw and the flame sensor. Clean with an emery cloth.  
Flame Sensor  
Remove dirt and grease from the motor, the fan guard, and blades. Use care when  
cleaning the fan blades to prevent causing misalignment or imbalance. Check that  
the hub of the fan blades is secure to the shaft.  
Follow these instructions for replacement of the fan guard, fan motor and/or fan  
blades.  
30. Fan Motor,  
Fan Blades,  
and Guard  
1. If the heater is installed, turn off the gas and disconnect the electric power.  
2. Open the access door and disconnect the fan motor wires, capacitor wires at the  
capacitor, and ground screw.  
3. Remove the assembled parts (the fan guard, the motor and the fan blade).  
4. Disassemble and replace whatever parts are needed and reas-  
semble using whatever part(s) are being replaced and the original  
parts.  
FIGURE 21 - Fan Blade  
Position on the Shaft  
Dimension A  
Size inches mm  
A
1
25  
30  
45  
60  
Fan  
Blade  
9/16 14  
1-1/2 38  
2-1/8 54  
2-3/8 60  
2-5/16 59  
2-3/8 60  
2-1/8 54  
1-5/8 67  
Be sure the fan blade is in the proper position on the shaft; refer to  
the illustration and table in FIGURE 21.  
Fan  
Motor  
75  
Position the assembly on the heater. Attach the fan guard.  
Rotate the fan blade to check for adequate clearance. If adjustment  
is required, loosen the mounting screws, re-position the fan guard,  
and tighten the screws. Rotate the fan blade and re-check for ad-  
equate clearance. Repeat this procedure until the assembly is posi-  
tioned properly.  
100  
125  
150  
175  
200  
225,  
250,  
300  
350  
400  
2
51  
5. Reconnect the fan motor wires according to the wiring diagram and close the  
access panel.  
6. Restore power to the heater and turn on the gas. Light, following the instructions  
on the lighting instruction plate. Check for proper operation.  
1-7/8 48  
1-3/8 35  
Remove dirt and grease from the motor casing, the venter housing, and the venter  
wheel. Venter motor bearings are permanently lubricated. Follow these instruc-  
tions for replacement of the venter motor and wheel assembly. Keep all hardware  
removed to be used in re-assembling and installing the replacement parts.  
1. Turn off the gas and disconnect the electric power.  
31. Venter Motor  
and Wheel  
Replacement Instructions  
2. Open the burner/control compartment access panel.  
3. Disconnect the three venter motor wires at the DSI control, capacitor wires at  
the capacitor (if applicable), and ground screw (located on the control panel).  
4. Sizes 30 and 45 - Disconnect the gas train and move it out of the way. Discon-  
nect the gas supply at the union outside of the cabinet. At the gas valve, mark  
and disconnect the wires. Carefully remove the burner orifice and orifice adapter  
locking nut. Slide the orifice adapter out through the bracket on the burner push-  
ing the gas train to the right. This will move the gas train out of the way.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 32  
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5. Holding the venter motor, remove the three or four screws that attach the venter  
motor mounting plate to the venter housing. Remove the motor and wheel as-  
sembly from the heater.  
6. Re-assemble with the replacement venter motor and wheel assembly. See FIG-  
URE 22.  
7. Follow the wiring diagram to connect the venter wires.  
8. Sizes 30 and 45 - Reconnect the gas supply at the union outside of the cabinet.  
Leak test the connection with leak detecting solution.  
9. Replace the access panel. Restore power to the heater and turn on the gas. Light,  
following the instructions on the lighting instruction plate. Check for proper  
operation.  
FIGURE 22 - Venter Wheel  
Position on Shaft  
Venter Motor Plate  
Venter Motor Plate  
Fan  
Venter Wheel,  
Sizes 30-75  
Venter Wheel,  
Sizes 100-175*  
Fan  
Motor Mounting Bracket  
Motor Mounting  
Bracket  
Motor Sizes  
100-400  
Motor  
Sizes  
30-75  
*Venter wheel has  
different appearance  
on Sizes 200-400.  
Motor spacing is  
the same.  
5/16” (8mm) inside  
5/16” (8mm) inside  
The gas valve requires no field maintenance except careful removal of external  
dirt accumulation and checking of wiring connections. Instructions for testing  
pressure settings re in Paragraph 12.  
32. Operating  
Gas Valve  
WARNING: The operating valve is the  
prime safety shutoff. All gas supply  
lines must be free of dirt or scale before  
connecting to the unit to ensure positive  
closure. See Hazard Levels, page 2.  
Optional  
Two  
Stage  
Gas  
Single  
Stage  
Gas  
Valve  
Valve  
See FIGURE 18, page 31, for location. If it is determined that  
the pressure switch needs replacing, use only the factory-autho-  
rized replacement part that is designed for the model and size of  
heater being serviced.  
33. Combustion  
Air Pressure  
Switch  
NOTE: A unit operating above 6000 ft elevation requires a high  
altitude pressure switch. See Paragraph 7.  
If it is determined that the limit control needs replacing, use only  
a factory-authorized replacement part that is designed for the  
size of heater.  
34. Limit Control  
For approximate limit location, see FIGURE 18, page 31.  
If it is determined that the door switch needs replacing, use only  
a factory-authorized replacement part that is designed for the  
heater.  
35. Door Switch  
- UDAS only  
For approximate switch location, see FIGURE 18, page 31.  
See FIGURE 18, page 31, for location. Use a voltmeter to verify  
that there are 24 volts output from the transformer. If the trans-  
former is not functioning, it must be replaced. Use a replacement  
36.Transformer  
transformer identical to the factory-installed model.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 33  
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The cause of a flame rollout switch activating must be determined. Activation of  
the manually reset flame rollout switch could be caused by one or more of the  
following:  
37. Flame  
Rollout  
• Restricted or plugged  
heat exchanger  
• Pressurization of the  
heat exchanger  
• Restricted combustion air inlet or exhaust outlet  
in combination with a defective pressure switch  
• Building exhaust  
Switch -  
Sizes 30-125  
only  
• Electrical power interruption during operation  
If a flame rollout switch trips, inspect the burner/control compartment for signs of  
excessive heat and burned wiring.  
If the compartment appears normal, reset by depressing the red button on the  
switch. 15 to 20 minutes are required for the switch to cool sufficiently for reset-  
ting. A distinct click will be felt when the switch resets. Operate the furnace. If  
the flame rollout switch trips again, determine and correct the cause before reset-  
ting the switch.  
For location, see  
FIGURE 18, page 31.  
If there is damage to the control compartment, repairs must be made before  
resetting the switch.  
If it is determined that the flame rollout switch needs replacing, use only the fac-  
tory-authorized replacement part that is designed for that size of heater.  
The disconnect switch is located in the sealed electrical box inside the con-  
trol compartment with the toggle on the rear of the heater.  
If it is determined that the disconnect switch needs replacing, use only the  
factory-authorized replacement part that is designed for the heater. Always  
replace electrical box cover.  
38. Disconnect  
Switch -  
UDAS only  
Check the complete system at least once a year. Inspection should include all joints,  
seams, concentric adapter box (UDAS), inlet air guard or inlet air cap (UDAS), and  
the vent terminal cap. Clean openings. Replace any defective parts.  
39. Vent or Vent/  
Combustion  
Air System  
40. Troubleshooting  
Trial for Ignition  
Call for Heat  
DSI Integrated Control Module  
(Circuit Board) Trial  
Troubleshooting  
Is there a  
spark across gap at  
ignitor?  
YES  
NO  
Flowchart  
Is there  
spark voltage at  
control?  
Check high  
voltage wire  
continuity.  
YES  
NO  
Does gas  
ignite?  
NO  
YES  
NO  
Is there minimum  
flame current at the  
flame sensor?  
Is the flame  
sensor corroded?  
Replace  
control  
module.  
YES  
YES  
Clean flame  
sensor.  
Is there 24V P1-2  
to power control?  
YES  
NO  
NO  
Is there  
minimum flame current  
at the control  
Is the sensor  
located in flame  
correctly?  
Check wiring  
and/or 24VAC  
transformer output.  
YES  
Replace control  
module.  
YES  
Replace flame  
sesnsor.  
module?  
NO  
NO  
Check connections to flame  
sensor and/or moisture in the  
burner assembly.  
Reposition  
flame sensor.  
YES  
Is gas  
flowing?  
NO  
Check gas pressure  
and supply voltage.  
If either are low,  
correct and repeat  
startup.  
Is the ignitor  
position correct in the  
gas flow?  
Is there  
24VAC at the gas  
valve?  
YES  
Replace gas  
valve.  
YES  
NO  
NO  
Is there 24VAC  
from gas valve output on  
control module to  
chassis?  
Replace  
ignition  
control  
module.  
Check wiring and  
connections to  
gas valve.  
Reposition  
spark ignitor.  
YES  
NO  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 34  
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The integrated circuit board monitors the operation of the heater and includes two  
LED signal lights that indicate normal operation and various abnormal conditions.  
If the heater fails to operate properly, check this signal to determine the cause and/  
or to eliminate certain causes. See operating sequence in Paragraph 20.  
Check the Lights on  
the DSI Integrated  
Control Module  
(Circuit Board)  
Do not attempt to repair the DSI integrated control module; the only field replace-  
able component is the fuse.  
IMPORTANT: When using a  
multimeter to troubleshoot the  
24 volt circuit, place the  
meter’s test leads into the 5 or 9  
pin connectors located on the  
ignition control. Do not  
remove connectors or terminals  
from the electrical components.  
Doing so can result in misinter-  
preted readings due to the  
ignition control board’s fault  
mode monitoring circuits.  
Control Status - Green LED Codes  
Steady ON.. Normal Operation, No call  
4 Flashes .... Pressure Switch is Closed  
Before Venter Motor is  
Energized  
Steady OFF Blown fuse, No Power, or  
for heat  
Fast Flash ... Normal Operation, Call for  
heat  
Defective Board  
1 Flash........ System Lockout, Failed to  
Flame Status - Yellow LED Codes  
detect or sustain flame  
Steady ON.. Flame is sensed  
2 Flashes .... Pressure Switch Did Not  
Slow Flash . Weak flame (current below  
Close within 30 Seconds of  
1.0 microamps ± 50%)  
Venter Motor  
Fast Flash ... Undesired Flame (valve  
3 Flashes .... High Limit or Flame  
open and no call for heat)  
Rollout Switch Open  
General Troubleshooting  
PROBLEM PROBABLE CAUSE  
REMEDY  
1. No power to unit.  
1. Turn on power; check supply fuses or main circuit breaker. Turn on  
built-in disconnect switch (Model UDAS only); replace switch if not  
operating.  
Venter motor  
will not start  
2. No 24 volt power to integrated circuit board. 2. Turn up thermostat; check control transformer output.  
3. Integrated circuit board fuse blown.  
4. No power to venter motor.  
5. Integrated circuit board defective.  
6. Defective venter motor.  
3. Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).  
4. Tighten connections at circuit board and/or motor terminals.  
5. Replace intergrated circuit board.  
6. Replace venter motor. See Paragraph 31.  
1. Open manual valve.  
1. Manual valve not open.  
Burner will  
not light  
2. Air in the gas line.  
2. Bleed gas line (initial startup only).  
3. Gas pressure too high or too low.  
3. Supply pressure should be 5" - 14" w.c. for natural gas or 11" - 14" w.c.  
for propane gas.  
4. No Spark:  
4.  
a) Loose wire connections.  
b) Transformer failure.  
a) Be certain all wire connections are solid.  
b) Be sure 24 volts is available.  
c) Incorrect spark gap.  
c) Maintain spark gap at 1/8".  
d) Spark cable shorted to ground.  
e) Spark electrode shorted to ground.  
f) Burner not grounded.  
g) Circuit board not grounded.  
h.) Unit not properly grounded.  
d) Replace worn or grounded spark cable.  
e) Replace if ceramic spark electrode is cracked or grounded.  
f) Make certain integrated circuit board is grounded to ignitor.  
g) Make certain integrated circuit board is grounded to furnace chassis.  
h.) Make certain unit is properly field grounded to earth ground and  
properly phased (L1 to hot lead L2 to neutral).  
i) Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).  
j) If 24 volt is available to the integrated circuit board and all other causes  
have been eliminated, replace board.  
i) Integrated circuit board fuse blown.  
j.) Faulty intergrated circuit board.  
5. Lockout device interrupting control circuit 5. Reset lockout by interrupting control at the thermostat or main power.  
by above causes.  
6. Interlock door switch open (UDAS only).  
7. Combustion air proving switch  
not closing.  
6. Close access door or replace switch.  
7.  
a) Make sure unit is properly vented.  
b) Remove obstructions from vent.  
c) Replace faulty tubing to pressure switch.  
8. Replace combustion air proving switch.  
9.  
8. Faulty combustion air proving switch.  
9. Main valve not operating.  
a) Defective valve.  
a) If 24 volt is measured at the valve connections and valve remains  
closed, replace valve.  
b) Loose wire connections  
b) Check and tighten all wiring connections.  
Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 35  
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40. Troubleshooting (cont’d)  
PROBLEM (cont’d)  
Burner will not light  
(cont’d)  
PROBABLE CAUSE (cont’d)  
10. Integrated circuit board does not power  
main valve.  
REMEDY (cont’d)  
10.  
a) Loose wire connections.  
b) Flame sensor grounded.  
a) Check and tighten all wiring connections.  
b) Be certain flame sensor lead is not grounded or insulation or  
ceramic is not cracked. Replace as required.  
c) Supply pressure should be 5" - 14" w.c. for natural gas or 11" - 14"  
w.c. for propane gas.  
c) Incorrect gas pressure.  
d) Cracked ceramic at sensor.  
d) Replace sensor.  
1. Gas pressure too high or too low.  
1. Supply pressure should be 5" - 14" w.c. for natural gas or 11" - 14"  
w.c. for propane gas.  
Burner cycle on and off  
2. Burner not grounded  
3. Circuit board not grounded.  
4. Faulty integrated circuit board  
2. Make certain integrated circuit board is grounded to ignitor.  
3. Make certain integrated circuit board is grounded to furnace chassis.  
4. If 24 volt is available to the integrated circuit board and all other  
causes have been eliminated, replace board.  
5.  
5. Combustion air proving switch  
not closing.  
a) Make sure unit is properly vented.  
b) Remove obstructions from vent.  
c) Replace faulty tubing to pressure switch.  
6. Replace combustion air proving switch.  
7. Be certain flame sensor lead is not grounded or insulation or ceramic  
is not cracked. Replace as required.  
6. Faulty combustion air proving switch.  
7. Flame sensor grounded.  
8. Cracked ceramic at sensor.  
9. Incorrect polarity.  
1. Incorrect valve outlet pressure or orifice.  
2. Cycling on limit control.  
8. Replace sensor.  
9. Reverse line volt leads to integrated circuit board.  
1. Check valve outlet pressure. See Rating plate for manifold pressure.  
2. Check air throughput.  
No heat (Heater  
Operating)  
3. Improper thermostat location or adjustment. 3. See thermostat manufacturer’s instructions.  
1. Circuit open.  
2. Defective integrated circuit board.  
1. Check wiring and connections.  
2. Replace board.  
Fan or venter motor will  
not run  
3. Defective motor or starter.  
3. Replace motor or starter.  
1. Motor overload device cycling on and off. 1. Check motor load against motor rating plate. Replace motor if  
needed.  
Fan or venter motor  
turns on and off while  
burner is operating  
Fan or venter motor cuts  
out on overload  
1. Low or high voltage supply.  
2. Defective motor.  
1. Correct electric supply.  
2. Replace motor.  
3. Poor air flow.  
4. Defective bearing or lubrication.  
3. Clean motor, fan, fan guard, filter, and coils.  
4. Lubricate bearings (motor permitting) or replace motor.  
FOR SERVICE OR REPAIR, FOLLOW THESE STEPS IN ORDER:  
Contact the Installer  
FIRST:  
Name __________________________________________________________  
Address_________________________________________________________  
__________________________________________________________  
__________________________________________________________  
Phone _____________________________________  
SECOND:  
THIRD:  
Contact the nearest distributor (See Yellow Pages). If no listing,  
contact Authorized Factory Representative, 1-800-695-1901 (Press 1).  
Contact  
REZNOR®/ Thomas & Betts Corporation  
150 McKinley Avenue  
Mercer, PA 16137  
Phone: (724) 662-4400  
Date of  
Model No. ______________Unit Serial No._____________________________ Installation _______________  
(800) 695-1901; www.ReznorOnLine.com  
©2003 Thomas & Betts Corporation, All rights reserved.  
Printed in the U.S.A.  
MANUFACTURER OF HEATING, COOLING, AND VENTILATING SYSTEMS  
Trademark Note: Reznor®, TCORE2® , and  
are trademarks of Thomas & Betts.  
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 36  
1/03 YL Form RZ-NA I-UDA (Version .5)  
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