Roberts Gorden Gas Heater CTU 22 TO 115 User Guide
FOR YOUR SAFETY  
If you smell gas:  
1. Open windows.  
2. DO NOT try to light any appliance.  
3. DO NOT use electrical switches.  
4. DO NOT use any telephone in  
your building.  
®
Combat  
5. Leave the building.  
6. Immediately call your local gas  
supplier after leaving the building.  
Follow the gas supplier’s  
instructions.  
7. If you cannot reach your gas  
supplier, call the Fire Department.  
Tubular Unit Heaters  
Installation, Commissioning,  
Operation & Service Manual  
WARNING  
Model CTU  
22 to 115  
Fire Hazard  
Do not store or use petrol or other  
flammable vapours and liquids in the  
vicinity of this or any other appliance.  
Some objects will catch fire or explode  
when placed close to heater.  
Failure to follow these instructions can  
result in death, injury or property  
damage.  
Installer  
WARNING  
Please take the time to read and understand  
these instructions prior to any installation.  
Installer must give a copy of this manual to the owner.  
Improper installation, adjustment, alteration, service  
or maintenance can result in death, injury or property  
damage. Read the installation, operation and service  
manual thoroughly before installing or servicing  
this equipment.  
Owner  
Keep this manual in a safe place in order to provide  
your serviceman with necessary information.  
Installation must be done by a registered installer/  
contractor qualified in the installation and service  
of gas-fired heating equipment or your gas supplier.  
Roberts-Gordon Europe Limited  
Unit A, Kings Hill Business Park  
Darlaston Road, Wednesbury  
West Midlands WS10 7SH UK  
Telephone: +44(0)121 506 7700  
Fax: +44 (0)121 506 7701  
Service Telephone: +44 (0)121 506 7709  
Service Fax: +44 (0)121 506 7702  
E-mail: [email protected]  
Quality in Any Language™  
E-mail: [email protected]  
© Copyright 2007 Roberts-Gordon, LLC  
www.rg-inc.com  
P/N X407UK Rev G 10/07  
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TABLE OF CONTENTS  
SECTION 1: Heater Safety......................................................2 SECTION 12: User Instructions............................................28  
SECTION 2: Installer Responsibility .....................................2  
2.1 Clearances to Combustibles........................................2  
2.2 Corrosive Chemicals....................................................2  
2.3 National Standards and Applicable Codes ..................2  
SECTION 3: Critical Considerations .....................................3  
12.1 User Instructions......................................................28  
12.2 Heater Operation......................................................28  
12.3 Common User Controls............................................28  
12.4 Lighting Instructions.................................................28  
12.5 Simple Fault Finding.................................................29  
3.1 Basic Information.........................................................3 SECTION 13: Servicing.........................................................30  
3.2 Location and Suspension ............................................3  
3.3 Minimum Required Installation Clearances .................3  
3.4 Clearances to Combustibles........................................3  
3.5 Ventilation ....................................................................3  
3.6 Gas Supply..................................................................3  
3.7 Electrical Supply..........................................................3  
13.1 Servicing Instructions...............................................30  
13.2 Burner Maintenance.................................................30  
13.3 Fan/Motor Assembly Maintenance...........................30  
13.4 Heat Exchanger Maintenance..................................30  
13.5 Gas Control Valve Maintenance...............................30  
13.6 Flue Fan ...................................................................30  
3.8 Flue..............................................................................3 SECTION 14: Conversion Between Gases..........................31  
SECTION 4: Specifications ....................................................5  
4.1 CTUA ..........................................................................5  
4.2 CTUB, CTUC and CTUD.............................................6  
14.1 General ....................................................................31  
14.2 Burner Conversion ...................................................31  
14.3 Gas Valves ...............................................................31  
4.3 General Technical Data Table .....................................7 SECTION 15: Troubleshooting .............................................32  
4.4 Technical Data Table....................................................8  
SECTION 5: Heater Installation..............................................9  
5.1 General........................................................................9  
5.2 Handling ......................................................................9  
5.3 Shelf Mounting and Suspension..................................9  
15.1 General ....................................................................32  
15.2 Troubleshooting For Automatic Ignition Burner  
Systems ...................................................................33  
15.3 Troubleshooting for Flame Supervision System .......34  
15.4 Troubleshooting for Solenoid Valves ........................34  
SECTION 6: Flue Installation ............................................... 10 SECTION 16: Removal and Replacement Parts..................35  
6.1 Flue Installation.......................................................... 10  
6.2 Type C12, C32 & C62 Appliance.................................... 10  
6.3 Type B22 Appliance..................................................... 10  
SECTION 7: Air Supply......................................................... 12  
7.1 Room Sealed Installation ........................................... 12  
7.2 Open Flued Installation .............................................. 12  
7.3 Building Ventilation..................................................... 12  
7.4 Isolated Equipment Rooms ........................................ 12  
SECTION 8: Optional Heater Configurations...................... 13  
8.1 Distribution Duct Work for CTUB, CTUC and CTUD  
Heaters ...................................................................... 13  
SECTION 9: Gas Piping........................................................ 14  
9.1 Connections............................................................... 14  
SECTION 10: Wiring and Electrical Information................. 15  
10.1 Electrical Supply ...................................................... 15  
10.2 Remote Controls ...................................................... 15  
10.3 CTUA Wiring Diagram (Models 22-60) .................... 16  
10.4 CTUA Wiring Diagram (Models 75-115)................... 17  
10.5 CTUB/C Wiring Diagram (Models 22-40)................. 18  
10.6 CTUB/C Wiring Diagram (Models 50-60)................. 19  
10.7 CTUB/C Wiring Diagram (Models 75-115) ...............20  
10.8 CTUD Wiring Diagram (Models 22-60)....................21  
10.9 CTUD Wiring Diagram (Models 75-115)...................22  
10.10 CTUD External Motor Alternative Wiring &  
16.1 Gas Valve.................................................................35  
16.2 Burner Compartment ...............................................36  
16.3 Ignition Electrode and Flame Probe.........................37  
16.4 Flue Fan ...................................................................38  
16.5 Pressure Switch........................................................39  
16.6 Ignition Control.........................................................40  
16.7 CTUA Axial Fan/Guard/Motor Assembly..................40  
16.8 CTUB & CTUC Centrifugal Fan/Guard/Motor  
Assembly..................................................................40  
16.9 Fan Data...................................................................41  
Optional Thermostat/Time Switch ..........................23  
SECTION 11: Commissioning..............................................24  
11.1 Pre-Commission Checks ..........................................24  
11.2 Gas Supply...............................................................24  
11.3 Mechanical Checks...................................................24  
11.4 Begin Commissioning...............................................24  
11.5 Combustion Testing ..................................................26  
11.6 Turning Off the Heater ..............................................26  
11.7 External Controls ......................................................27  
11.8 Complete the Commissioning...................................27  
11.9 Instruction to the User ..............................................27  
© 2007 Roberts-Gordon, LLC  
All rights reserved. No part of this work covered by the copyrights herein may be reproduced  
or copied in any form or by any means - graphic, electronic, or mechanical, including  
photocopying, recording, taping or information storage and retrieval systems - without the  
written permission of Roberts-Gordon, LLC.  
Printed in U.K.  
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TABLE OF FIGURES  
Figure 1: Installation Clearances and Clearances to  
Combustibles.............................................................4  
Figure 2: Suspension Methods .................................................9  
Figure 3: Flue and Roof Detail ................................................ 10  
Figure 4: Air Intake Terminal Cover......................................... 10  
Figure 5: Vertical and Horizontal Flue Termination -  
Type B22 Appliance .................................................. 11  
Figure 6: Vertical and Horizontal Flue Termination -  
Type C12 C32 & C62 Appliances................................. 11  
Figure 7: Heaters Installed in Isolated Equipment Rooms ...... 12  
Figure 8: Ducting..................................................................... 13  
Figure 9: Gas Connection with Stainless Steel Flex  
Connector................................................................ 14  
Figure 10: Automatic Burner Control Box Sequence...............25  
Figure 11: Gas Valve for Heater (Models 22 - 60) ...................25  
Figure 12: Gas Valve for Heater (Models 75 - 115) .................26  
Figure 13: Heater Operating Sequence ..................................28  
Figure 14: Centrifugal Fan Orientation....................................41  
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Product Approval  
ROBERTS GORDON® appliances have been tested and CE certified as complying with the essential  
requirements of the Gas Appliance Directive, the Low Voltage Directive, the Electromagnetic  
Compatibility Directive and the Machinery Directive for use on natural gas and LPG when installed,  
commissioned and maintained in accordance with these instructions.  
These instructions refer to appliances designed to operate in the European Union.  
Appliances designed for other countries (Non-European Union) are available on request.  
This appliance must be installed in accordance with the local and national codes in force and used  
only in a sufficiently ventilated space, as specified in these instructions.  
Before installation, check that the local gas distribution systems, nature of gas and pressure, and  
adjustment of the appliance are compatible.  
1
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 1: HEATER SAFETY  
Your Safety is Important to Us!  
2.2 Corrosive Chemicals  
This symbol is used throughout the  
manual to notify you of possible fire,  
electrical or burn hazards. Please pay  
special attention when reading and  
following the warnings in these sections.  
CAUTION  
Do not use heater in an area containing corrosive  
chemicals.  
Installation, service and annual inspection of heater  
must be done by a registered installer/contractor  
qualified in the installation and service of gas-fired  
heating equipment.  
Corrosive chemicals will damage the burner and  
heat exchanger parts.  
Failure to follow these instructions can result in  
property damage.  
Read this manual carefully before installation,  
operation, or service of this equipment.  
Roberts-Gordon cannot be responsible for ensuring  
that all appropriate safety measures are undertaken  
prior to installation; this is entirely the responsibility  
of the installer. It is essential that the contractor, the  
sub-contractor, or the owner identifies the presence  
of combustible materials, corrosive chemicals or  
halogenated hydrocarbons* anywhere in the  
premises.  
This heater is designed for heating non-residential  
indoor spaces. Do not install in residential spaces.  
These instructions, the layout drawing, local codes  
and ordinances, and applicable standards that apply  
to gas piping, electrical wiring, venting, etc. must be  
thoroughly understood before proceeding with the  
installation.  
* Halogenated Hydrocarbons are a family of chemical  
compounds characterized by the presence of halogen  
elements (fluorine, chlorine, bromine, etc.). These com-  
pounds are frequently used in refrigerants, cleaning  
agents, solvents, etc. If these compounds enter the air  
supply of the burner, the lifespan of the heater compo-  
nents will be greatly reduced. Warranty will be invalid if  
the heater is exposed to halogenated hydrocarbons.  
SECTION 2: INSTALLER RESPONSIBILITY  
• To install the heater, as well as the gas and elec-  
trical supplies, in accordance with applicable  
specifications and codes. Roberts-Gordon  
recommends the installer contact a local  
building inspector, Fire Officer or insurance  
company for guidance.  
2.3 National Standards and Applicable Codes  
• To use the information given in the manual  
together with the local and national codes to  
perform the installation.  
All appliances must be installed in accordance with  
the latest revision of applicable standards and local  
and national codes. This refers also to the electric,  
gas and venting installation. Note: Additional  
standards for installations in public garages, aircraft  
hangars, etc. may be applicable.  
• To install the heater in accordance with the  
Clearances to Combustibles of this heater.  
• To furnish all needed materials not furnished  
as standard equipment.  
• To plan location of supports, flues and air  
intakes.  
• To provide access to burners for servicing.  
• To provide the owner with a copy of this  
Installation, Commissioning, Operation and  
Service Manual.  
• To never use heater as support for ladder or  
other access equipment and never hang or  
suspend anything from heater.  
• To ensure that there is sufficient ventilation in the  
area to comply with the requirements of  
all relevant local and national codes.  
2.1 Clearances to Combustibles  
In all situations, clearances to combustibles must be  
maintained. Caution must be used when running the  
heater near combustible materials such as wood,  
paper, rubber, etc. A wall tag (P/N 91040028) is on  
the back cover of this manual as a permanent  
reminder of the safety instructions and the  
importance of the required clearances to  
combustibles. Affix the tag on a wall near the heater.  
2
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SECTION 3: CRITICAL CONSIDERATIONS  
SECTION 3: CRITICAL CONSIDERATIONS  
3.1 Basic Information  
3.8 Flue  
CTU heaters have automatic ignition burners for  
ON/OFF operation only.  
Choose heater siting to allow for the proper location  
of the flue. Each heater must be fitted with an  
individual and correctly sized sealed flue system  
(See Page 10, Section 6).  
3.2 Location and Suspension  
All models:  
No other appliance may be connected to the flue.  
For room sealed installation, the air intake must be  
the same size sealed system and the flue/air intake  
must terminate at an approved concentric wall or  
roof terminal.  
• Must be installed indoors.  
• Must be installed in a level position.  
• May be mounted on a shelf of non-combustible  
material. (See Page 5, Section 4 and Page 9,  
Figure 2 for support points)  
• May be suspended from above (See Page 9,  
Figure 2) or from wall brackets of sufficient  
strength to support the heater as listed in the  
Dimension Data Table on Page 5, Section 4.1.  
Drop rods must be a minimum of 10 mm diame-  
ter mild steel. Four suspension points (M10 nuts)  
are located on top of the heater.  
• Must be installed in a manner which allows the  
hinged door to be fully opened to provide access  
to all serviceable components.  
3.3 Minimum Required Installation Clearances  
Clearances around the heater and flue must be as  
indicated on Page 4, Figure 1, Page 10, Figure 3  
through Page 11, Figure 6 to ensure access for  
servicing, and correct operation.  
3.4 Clearances to Combustibles  
Clearances must be as indicated on Page 4, Figure  
1. If clearances to combustibles are not indicated,  
then installation clearances apply.  
3.5 Ventilation  
It is important to ensure that there is adequate air  
circulation around the heater to supply air for  
combustion, ventilation and distribution in  
accordance with local and national codes.  
3.6 Gas Supply  
It is important that the gas supply pipe is sized  
correctly to provide the inlet pressure as stated on  
the heater data plate. The gas supply pipe and  
electrical connections must not support any of the  
heater's weight.  
3.7 Electrical Supply  
A permanent 230 V 50 Hz electrical supply is  
required at the main electrical terminals. The heater  
also requires suitable energy controls in accordance  
with Section 10.  
3
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
WARNING  
Fire Hazard  
Some objects will catch fire or explode when placed  
close to heater.  
Keep all flammable objects, liquids and vapours the  
required distance away from the heater.  
Failure to follow these instructions can result in death,  
injury or property damage.  
Figure 1: Installation Clearances and Clearances to Combustibles  
Installation Clearances  
Roof Terminal  
Clearances to Combustibles  
Air  
15 cm  
30 cm  
15 cm  
Intake  
50 cm  
50 cm**  
3 m  
Flue  
Wall  
Terminal  
60 cm  
2.5 - 3.5 m*  
* Heaters may be mounted at a higher level if  
destratification fans and/or turn down nozzles are  
installed.  
**80 cm is necessary to service heater.  
The heater must always be installed at least 2.5 m above the floor.  
The flue pipe must have clearance from combustibles by 5 cm.  
If installed at low levels where individuals can come in contact with hot heat exchanger components,  
adequate guarding must be provided.  
All distances are minimum clearance requirements for service access, air flow and safety.  
4
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SECTION 4: SPECIFICATIONS  
SECTION 4: SPECIFICATIONS  
4.1 CTUA  
Top View  
Heater must be supported  
at these points from above  
or below.  
C
E
D
77  
4 x M10 Captive Nuts Provided  
Support  
Centers  
492  
End View  
J
Z
646  
Rear View  
Air Intake  
F
G
B
H
Flue  
Lockout Reset  
Electrical  
Cable Entry  
Gas  
Supply  
168  
A
Dimension Data - CTUA (All Models)  
Model  
22  
30  
35  
40  
50  
60  
75  
90  
100  
115  
mm  
(in)  
mm  
(in)  
mm  
(in)  
mm  
(in)  
mm  
(in)  
mm  
(in)  
mm  
(in)  
mm  
(in)  
1075  
1075  
1075  
1075  
1075  
1075  
1327  
1327  
1327  
1327  
A
B
C
D
E
F
G
H
J
Width  
(42.3)  
(42.3)  
(42.3)  
(42.3)  
(42.3)  
(42.3)  
(52.3)  
(52.3)  
(52.3)  
(52.3)  
895  
(35.2)  
450  
(17.7)  
312  
(12.3)  
315  
(12.4)  
430  
(16.9)  
140  
(5.5)  
211  
(8.3)  
150  
(5.9)  
895  
(35.2)  
450  
(17.7)  
312  
(12.3)  
315  
(12.4)  
430  
(16.9)  
140  
(5.5)  
211  
(8.3)  
150  
(5.9)  
1100  
(43.3)  
627  
(24.7)  
312  
(12.3)  
388  
(15.3)  
346  
(13.6)  
225  
(8.9)  
260  
(10.2)  
220  
(8.7)  
1100  
(43.3)  
627  
(24.7)  
312  
(12.3)  
388  
(15.3)  
346  
(13.6)  
225  
(8.9)  
260  
(10.2)  
220  
(8.7)  
1345  
(53)  
627  
(24.7)  
312  
(12.3)  
388  
(15.3)  
537  
(21.1)  
225  
(8.9)  
260  
(10.2)  
220  
(8.7)  
610  
(24)  
450  
(17.7)  
312  
(12.3)  
315  
(12.4)  
240  
(9.5)  
140  
(5.5)  
218  
(8.6)  
150  
(5.9)  
610  
(24)  
450  
(17.7)  
312  
(12.3)  
315  
(12.4)  
240  
(9.5)  
140  
(5.5)  
218  
(8.6)  
150  
(5.9)  
610  
(24)  
450  
(17.7)  
312  
(12.3)  
315  
(12.4)  
240  
(9.5)  
140  
(5.5)  
218  
(8.6)  
150  
(5.9)  
610  
(24)  
450  
(17.7)  
312  
(12.3)  
315  
(12.4)  
240  
(9.5)  
140  
(5.5)  
218  
(8.6)  
150  
(5.9)  
1345  
(53)  
627  
(24.7)  
312  
(12.3)  
388  
(15.3)  
537  
(21.1)  
225  
(8.9)  
260  
(10.2)  
220  
(8.7)  
Height  
Support Spacing  
Support Spacing  
Support Spacing  
Centre of Flue  
Centre of Flue/Air Intake  
Position of Flue  
Gas Inlet Position  
Length  
mm  
(in)  
mm  
(in)  
756  
(29.8)  
756  
(29.8)  
756  
(29.8)  
756  
(29.8)  
806  
(31.8)  
806  
(31.8)  
756  
(29.8)  
756  
(29.8)  
806  
(31.8)  
806  
(31.8)  
Z
mm Ø  
(in) Ø  
100  
100  
100  
100  
100  
100  
130  
130  
130  
130  
Weight  
(5.1)  
(5.1)  
(5.1)  
(5.1)  
(3.9)  
(3.9)  
(3.9)  
(3.9)  
(3.9)  
(3.9)  
kg  
84  
84  
88  
92  
115  
122  
160  
169  
194  
203  
5
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
4.2 CTUB, CTUC and CTUD  
1440  
679  
K
115  
646  
L
M
N
N
End View  
End View  
CTUB/C (All Models)  
CTUC (All Models)  
115  
115  
P
646  
N
N
End View  
CTUD (All Models)  
Front View  
CTUD (And other models fitted with air outlet spigots)  
Dimension Data - CTUB, CTUC and CTUD  
Model  
22  
30  
35  
40  
50  
60  
75  
90  
100  
115  
mm  
(in)  
mm  
(in)  
mm  
(in)  
mm  
(in)  
1026  
1026  
1026  
1026  
1026  
1026  
1076  
1076  
1076  
1076  
K
L
CTUB Depth  
CTUB Height  
CTUC Height  
(40.4)  
(40.4)  
(40.4)  
(40.4)  
(40.4)  
(40.4)  
(42.4)  
(42.4)  
(42.4)  
(42.4)  
610  
(24)  
610  
(24)  
610  
(24)  
610  
(24)  
610  
(24)  
610  
(24)  
610  
(24)  
610  
(24)  
895  
(35.2)  
895  
(35.2)  
895  
(35.2)  
895  
(35.2)  
1100  
(43.3)  
1100  
(43.3)  
1100  
(43.3)  
1100  
(43.3)  
1380  
(54.3)  
1431  
(56.3)  
1380  
(54.3)  
1431  
(56.3)  
M
N
Inlet & Outlet Duct  
Spigot Height  
534  
(21)  
534  
(21)  
534  
(21)  
534  
(21)  
817  
(32)  
817  
(32)  
1024  
(40.3)  
1024  
(40.3)  
1233  
(48.5)  
1233  
(48.5)  
Inlet & Outlet Duct  
Spigot Width  
mm  
(in)  
709  
(27.9)  
709  
(27.9)  
709  
(27.9)  
709  
(27.9)  
707  
(27.8)  
707  
(27.8)  
888  
(35)  
888  
(35)  
888  
(35)  
888  
(35)  
P
Weight CTUB  
Weight CTUD  
kg  
kg  
kg  
96  
109  
93  
96  
109  
93  
100  
113  
97  
104  
117  
101  
139  
157  
124  
146  
163  
131  
185  
206  
172  
210  
215  
181  
228  
251  
200  
237  
260  
209  
NOTE: Inlet and outlet duct spigot fitted with 30 mm flange.  
6
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SECTION 4: SPECIFICATIONS  
4.3 General Technical Data Table  
CTU-22 CTU-30 CTU-35 CTU-40 CTU-50 CTU-60 CTU-75 CTU-90 CTU-100 CTU-115  
CTUA With Axial Fan  
Total Electrical Load  
Run Current  
W
A
210  
1.0  
210  
1.0  
210  
1. 0  
210  
1.0  
415  
1.72  
2.4  
415  
1.72  
2.4  
510  
1.9  
510  
1.9  
745  
3.2  
745  
3.2  
Start Current  
A
1.4  
1.4  
1. 4  
1.4  
2.8  
2.8  
4.5  
4.5  
Air Flow  
m3/h  
3800  
4000  
4000  
4000  
5500  
5500  
7500  
7500  
11,000  
11,000  
Sound Pressure Level [NR]  
at 3 m dB(A)  
[51]  
56  
[51]  
56  
[51]  
56  
[51]  
56  
[52.1]  
57.1  
[52.1]  
57.1  
[52.3]  
57.3  
[52.3]  
57.3  
[52.3]  
57.3  
[52.3]  
57.3  
CTUB with Centrifugal Fan and CTUC Range with Centrifugal Fan and Duct Inlet  
Total Electrical Load  
Normal Run Current  
Normal Start Current  
Normal Speed  
W
A
550  
4.6  
9.0  
550  
4.6  
9.0  
550  
4.6  
9.0  
550  
4.6  
9.0  
1100  
11.0  
1100  
11.0  
1100  
11.0  
1100  
11.0  
1650  
15.6  
19.2  
1650  
15.6  
19.2  
A
13.5  
13.5  
13.5  
13.5  
Medium Medium Medium Medium Medium Medium Medium Medium Medium Medium  
High Run Current  
High Start Current  
Air Flow  
A
A
5.5  
13.6  
3300  
5.5  
13.6  
3300  
5.5  
13.6  
3300  
5.5  
13.6  
3300  
14.0  
17.2  
14.0  
17.2  
14.0  
17.2  
14.0  
17.2  
21.0  
25.8  
9400  
21.0  
25.8  
9400  
m3/h  
5500  
5500  
6400  
6400  
Sound Pressure Level [NR]  
at 3 m dB(A)  
[59]  
59.5  
[59]  
59.5  
[59]  
59.5  
[59]  
59.5  
[61]  
61.5  
[61]  
61.5  
[62]  
61.8  
[62]  
61.8  
[63]  
64.2  
[63]  
64.2  
CTUD Duct Heater with No Fan  
**Minimun Air Flow  
Required  
m3/h  
Pa  
3300  
30  
3300  
30  
3300  
30  
3300  
30  
5500  
30  
5500  
30  
6400  
30  
6400  
30  
9400  
30  
9400  
30  
Pressure Loss Across  
Heat Exchanger  
Flue and AIr Intake  
Flue and Air Intake  
Size  
mm Ø  
m
100  
7
100  
8
100  
8
100  
10  
100  
13  
100  
15  
130  
15  
130  
17  
130  
20  
130  
20  
*Maximum Straight  
Flue/Air Intake  
Electrical load at 230 V 50 Hz measured by calculating from total run current of appliance.  
* Do not exceed the maximum length of flue stated or heater may not operate properly. Reduce the  
maximum length stated by 1 m for each 90° bend installed.  
**If minimum air flow requirements are not met, then temperature limit devices will shut down the heater.  
7
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
4.4 Technical Data Table  
Appliance Category II 2H/L 3B/P  
CTU-22 CTU-30 CTU-35 CTU-40 CTU-50 CTU-60 CTU-75 CTU-90 CTU-100 CTU-115  
Heat Input  
Gross CV  
kW  
27  
93  
33  
113  
39  
133  
48  
163  
61  
210  
70  
238  
95  
324  
111  
378  
119  
405  
134  
459  
(Btu/h) x (1000)  
Heat Input  
Net CV  
kW  
25  
84  
30  
102  
35  
119  
43  
147  
55  
189  
63  
215  
86  
292  
100  
341  
107  
365  
121  
414  
(Btu/h) x (1000)  
Approximate  
Heat Output  
kW  
23  
78  
27  
92  
32  
109  
39  
133  
51  
174  
58  
198  
78  
266  
91  
310  
98  
334  
111  
379  
(Btu/h) x (1000)  
Thermostat Limit Thermodisc  
CTUA,B/C,D °C  
75  
75  
75  
75  
75  
75  
75  
75  
75  
75  
Natural Gas (G20) Data - Inlet Pressure 20 mbar (7.8 in WG) Min. 17 mbar (6.8 in WG) Max. 25 mbar (10 in WG)  
Burner Pressure  
mbar  
8.3  
8.7  
8.5  
9.4  
9.3  
8.5  
6.1  
6.0  
6.2  
6.3  
m3/h  
ft3/h  
2.6  
92  
3.2  
112  
3.7  
131  
4.5  
160  
5.8  
206  
6.6  
234  
9.0  
319  
10.5  
371  
11.3  
398  
12.8  
451  
Gas Rate  
Natural Gas (G25) Data - Inlet Pressure 25 mbar (10 in WG) Min. 20 mbar (7.8 in WG) Max. 30 mbar (12 in WG)  
Burner Pressure  
mbar  
12.2  
12.7  
12.5  
14.0  
13.6  
13.2  
9.2  
9.3  
9.2  
10.2  
m3/h  
ft3/h  
3.03  
107  
3.33  
117  
4.31  
152  
4.78  
169  
6.14  
217  
6.98  
247  
9.49  
335  
11.06  
391  
11.86  
419  
13.43  
474  
Gas Rate  
LPG Gas Propane (G31) Data - Inlet Pressure 37 mbar (14.6 WG) Min. 25 mbar (10 in WG) Max. 45 mbar (18 in WG)  
Alternative where permitted 50 mbar (20 in WG) Min. 42.5 bar (17 in WG) Max. 57.5 mbar (23 in WG)  
Burner Pressure  
mbar  
26.6  
24.9  
25.4  
25.9  
25.6  
26.8  
25.6  
27.3  
25.3  
25.9  
m3/h  
kg3/h  
liquid/h  
1.01  
1.87  
3.7  
1.23  
2.28  
4.5  
1.48  
2.75  
5.4  
1.77  
3.27  
6.4  
2.27  
4.21  
8.3  
2.58  
4.79  
9.4  
3.51  
6.50  
12.8  
4.09  
7. 5 8  
14.9  
4.39  
8.13  
16.0  
4.97  
9.21  
18.1  
Gas Rate  
LPG Gas Butane (G30) Data - Inlet Pressure 29 mbar (11,4 in WG) Min. 20 mbar (7.8 in WG) Max. 35 mbar (13.8 WG)  
Burner Pressure  
mbar  
18.9  
17.4  
17.8  
19.5  
18.4  
19.0  
18.3  
19.4  
18.3  
18.7  
m3/h  
kg3/h  
liquid/h  
0.76  
1.86  
3.2  
0.93  
2.27  
4.0  
1.06  
2.59  
4.5  
1.34  
3.26  
5.7  
1.72  
4.19  
7. 3  
1.95  
4.77  
8.3  
2.65  
6.47  
11.3  
3.09  
7. 5 5  
13.2  
3.32  
8.09  
14.1  
3.75  
9.17  
16.0  
Gas Rate  
Gas rates corrected to standard conditions 1013.25 mbar 15° C.  
8
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SECTION 5: HEATER INSTALLATION  
SECTION 5: HEATER INSTALLATION  
5.1 General  
5.3 Shelf Mounting and Suspension  
Heaters are designed for installation above 2.5 m.  
These heaters must be installed within the heated  
space. Duct delivery systems are not permitted with  
axial fans.  
WARNING  
Crush Hazard  
Use 10 mm steel drop rod  
minimum.  
5.2 Handling  
Failure of the supports can  
result in death, injury  
or property damage.  
All CTU heaters are supplied secured to a wooden  
pallet and shrink wrapped. Use the pallet to support  
the heater during handling and installation. When  
handling or supporting the heater from below,  
ensure that the weight is taken at the support points.  
For typical suspension See Page 9, Figure 2.  
Figure 2: Suspension Methods  
Insure all suspension hardware  
is torqued to a minimum  
of 27 Nm (20 ft lbs)  
Unistrut  
Channel Nut  
Washer  
Nut  
10 mm  
Steel  
Drop Rod  
Cone Point  
Set Pin  
Window  
Clamp  
10 mm  
Steel  
Drop Rod  
Unistrut  
Nut  
Washer  
Riv  
Nut  
Support Points  
9
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 6: FLUE INSTALLATION  
6.1 Flue Installation  
Figure 3: Flue and Roof Detail  
WARNING  
Flue  
Terminal  
Masterflash  
Soaker Flashing  
or Rain Collar.  
Fire Hazard  
Some objects will catch fire or explode when placed  
close to heater.  
Keep all flammable objects, liquids and vapours the  
required distance away from the heater.  
Roof  
Failure to follow these instructions can result in death,  
injury or property damage.  
The flue must terminate outside of the building.  
Flues and air intakes must be a fully sealed system  
and correctly sized for the model. Flues should be  
assembled as detailed on Page 10, Figure 3 through  
Page 11, Figure 6. The joints between the flue  
terminal and the roof or wall must be properly  
sealed. If the flue passes through a wall or ceiling of  
combustible material, it must be enclosed by a  
sleeve of non-combustible material and be  
separated from the sleeve by at least a 25 mm air  
gap.  
Metal Sleeve  
Flue  
25 mm Air Gap to  
Combustible Material  
Figure 4: Air Intake Terminal Cover  
Flues and air intakes must be adequately  
supported so that the heater does not bear the  
weight of the pipes.  
Fold Leg  
Down  
For flue termination See Page 10, Figure 3 through  
Page 11, Figure 6.  
Fold Foot  
Out  
6.2 Type C12, C32 & C62 Appliance  
Room Sealed.  
The heaters are designed to be installed as room  
sealed appliances. The flue and air intake are run as  
separate pipes to the special concentric wall or roof  
terminal. See Page 11, Figure 6.  
6.3 Type B22 Appliance  
The flue must terminate outside the building and be  
fitted with a low resistance terminal.  
See Page 10, Figure 3 through Page 11, Figure 5.  
Fold Leg  
Down  
Fold Foot  
Out  
6.3.1 Air Intake Terminal Cover  
For Type B22 appliance installations, an air intake  
terminal cover is an available option. The cover is  
scored flat sheet metal that must be bent into shape.  
See Page 10, Figure 4. Remove and retain the  
screws for the air inlet spigot. Use these screws to  
attach the cover in position over the spigot.  
Description  
Air Intake Terminal Cover (100mm)  
Air Intake Terminal Cover (130mm)  
Part Number  
F078A  
F077A  
10  
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SECTION 6: FLUE INSTALLATION  
Figure 5: Vertical and Horizontal Flue Termination - Type B22 Appliance  
Roof Terminal  
Masterflash  
Metal Sleeve  
(25 mm air gap to  
Combustible Material)  
Flue  
Air Intake  
Terminal Cover  
Vertical  
Option  
90°  
Bend  
Masterflash  
Flue  
Horizontal  
Option  
Wall  
Terminal  
Figure 6: Vertical and Horizontal Flue Termination - Type C12 C32 & C62 Appliances  
Roof Terminal  
Plastic Cup  
Model  
Concentric Flue Diameter  
22-60 Cover (100mm)  
75-115 Cover (130mm)  
150mm  
200mm  
Masterflash  
Manifold  
Air Intake  
Flue  
Vertical  
Option  
Wall  
Terminal  
Wall  
End View  
Plate  
90° Bend  
Air Intake  
Flue  
Horizontal  
Option  
Manifold  
The minimum  
Max wall thickness  
335 mm  
gap must be  
positioned at bottom  
11  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 7: AIR SUPPLY  
7.1 Room Sealed Installation  
When installed as a room sealed heater, the air for  
7.3 Building Ventilation  
Where ventilation is required, air must be taken from  
combustion is drawn in from outside the building. It an outside point where it is not likely to be  
is important to ensure that there is adequate  
ventilation to provide air for the distribution fan/s.  
contaminated or obstructed.  
Where natural ventilation is used, suitable ventilation  
with outside air at low level must be provided in  
accordance with Section 7.2.1 and local and national  
codes.  
7.2 Open Flued Installation  
It is important to ensure that there is adequate air  
supply at all times for both combustion and heating  
Where mechanical ventilation is used, extract rate  
requirements in accordance with local and national must be 5% - 10% less than the inlet rate. The  
codes. When installed in this mode, the air supply to  
the heater must also be fitted with a low resistance  
terminal to prevent the ingress of debris. See Page  
11, Figure 5.  
mechanical ventilation must be interlocked with the  
burner on the CTU heater.  
7.4 Isolated Equipment Rooms  
Ventilation must prevent the isolated equipment  
room temperature from exceeding 32° C as well as  
prevent any negative air pressure within the room.  
See Page 12, Figure 7. Any isolated equipment  
room containing air heaters will require permanent  
air vents direct to outside air in compliance with local  
codes.  
Where natural ventilation is used, suitable  
permanent openings at low and high level,  
communicating directly with the outside air, must be  
provided.  
7.2.1 Heaters Installed Within the Heated Space  
Where the volume of the heated space is greater  
than 4.7 m3 per kilowatt of total rated heat input and  
the air change rate is at least 0.5/h, additional high  
and low level ventilation will not be required.  
For a building having an air change rate less than  
0.5/h, ventilation will be necessary in accordance  
with local and national codes. Ventilation direct to  
outside must be provided as follows:  
• Heaters up to 70 kW heat input: 5.0 cm2 per kW  
of rated heat input  
• Heaters above 70 kW heat input: 350 cm2 + 2.5  
cm2 per kW of rated heat input above 70 kW  
Where mechanical ventilation is used, extract rate  
must be 5% - 10% less than the inlet rate. The  
mechanical ventilation must be interlocked with the  
burner on the CTU heater.  
Figure 7: Heaters Installed in Isolated Equipment Rooms  
High Level  
Ventilation  
Manifold  
Air Intake  
Flue  
Duct Distribution  
System or  
Discharge to  
Heated Space  
Return Air Duct  
from Heated  
Space or Fresh  
Air from Outside  
Max Temperature 32° C  
Room Air Pressure Must Not be Negative.  
Low Level  
Ventilation  
Wall  
Outside  
Wall  
12  
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SECTION 8: OPTIONAL HEATER CONFIGURATIONS  
SECTION 8: OPTIONAL HEATER CONFIGURATIONS  
8.1 Distribution Duct Work for CTUB, CTUC and 8.1.1 CTUD Heaters  
CTUD Heaters  
CTUC heaters have the fans enclosed so that the  
heater may be connected to inlet ducting.  
CTUD heaters are supplied with inlet and outlet duct  
spigots for mounting the heater into a customer  
designed duct system for use with an external fan  
system.  
It is recommended that flexible duct connectors are  
used to reduce duct born noises.  
For CTUD heaters, it is essential that the airflow in  
the duct system is at least that specified in the Data  
Sheet on Page 6, Section 4.2 and in the correct  
direction across the heat exchanger as indicated by  
the arrow on the heater. Higher air flows are  
permitted, but will cause a lower exiting air  
temperature. It is recommended that the fan is  
positioned to blow the air through the heat  
exchanger.  
The duct must be designed as described on Page  
13, Section 8.1 and Figure 8 to ensure that there is a  
homogenous air flow across the whole of the heat  
exchanger.  
Failure to provide a suitable air flow properly  
distributed across the heat exchanger will reduce the  
life of the heat exchanger.  
When installing CTUD heaters onto ducting force  
the fan to run.  
Do not rely on the fan thermostat to turn it on.  
Any such device must be in parallel with the fan  
thermostat so that the fan run-on operation will still  
operate.  
The fan motor, or its control, must contain a method  
of overload protection. When installed remote from  
the heater, the fan must be supplied via a local  
electrical isolator positioned and properly labeled to  
prevent inadvertent operation.  
Contact Roberts-Gordon Europe Ltd. Design  
Department for recommendations regarding  
duct resistance and design. Tel: +44 (0) 121 506  
7700  
Figure 8: Ducting  
NOTE: Duct size will be full size of inlet and outlet.  
All joints between the heater and duct work should be  
made as air tight as possible.  
Dimension  
“X”  
Minimum-  
Twice  
Dimension  
“X”  
Airflow Indicator  
Minimum-  
Twice  
Dimension  
“X”  
Ducting  
Flexible Flange  
Ducting  
13  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 9: GAS PIPING  
9.1 Connections  
Connect the heater to the gas supply ensuring that  
the final connections are as follows:  
• Gas supply pipe work is run in medium or heavy  
gauge tubing in compliance with local and  
national codes.  
WARNING  
• The gas supply pipe is adequately sized to carry  
the total volume of gas for the complete  
installation.  
Fire Hazard  
• An isolating valve and union connection should  
be used and fitted into the supply adjacent to the  
heater.  
Connect gas supply according to Figure 9.  
Gas can leak if not installed properly.  
Failure to follow these instructions can result in death,  
injury or property damage.  
• For suspended heaters, use an approved metal  
flexible connection between the isolating valve  
and the heater. To reduce pressure loss, use  
one pipe size larger than the heater gas  
connection.  
It is important that the gas supply pipe and the  
electrical connections do not support any of the  
heater’s weight.  
A gas meter is connected to the service pipe by the  
gas supply company. An existing meter should be  
checked, preferably by the company, to ensure that  
the meter is adequate for the rate of gas supply  
required.  
IMPORTANT - The complete installation must be  
purged and tested for gas soundness in accordance  
with local and national codes.  
Installation pipes must be fitted in accordance with  
local and national codes. Pipe work from the meter  
to the heater(s) must be of adequate size. Pipes of  
smaller size than the heater inlet gas connection  
should not be used.  
Figure 9: Gas Connection with Stainless Steel Flex Connector  
• Hold gas nipple securely  
with pipe wrench when  
attaching the flex gas  
connector.  
Option A:  
Stainless Steel  
Flex Gas  
• Do not twist flexible  
gas connector.  
Connector  
• Ensure all joints are  
gas tight.  
Do not bend flexible  
gas connector sharply.  
Option B:  
Medium or Heavy  
Gauge Tubing  
Gas Connector  
Gas Isolating Valve  
Drip Leg  
Cap  
Union  
Connection  
14  
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SECTION 10: WIRING AND ELECTRICAL INFORMATION  
SECTION 10: WIRING AND ELECTRICAL INFORMATION  
10.1 Electrical Supply  
10.2.1 Burner Controls (Thermostat)  
All heaters need a constant 230 V 50 Hz single  
phase supply connected to terminals L, N & Earth.  
Polarity "L & N" must be correct. The voltage  
between neutral and earth should be 0 and never  
exceed 15 volts.  
All heaters and controls must be correctly earthed.  
All external wiring must comply with the relevant  
local codes. Wire specification H05VV-F.  
Controls to operate the burner must be voltage free  
contacts connected between terminals 2 & 3 of the  
main terminal block.  
10.2.2 Positioning Room Thermostats or  
ROBERTS GORDON® Control  
A room thermostat or ROBERTS GORDON®  
control should be mounted on a wall or column at a  
height of approximately 1.5 metres from the floor to  
measure the ambient temperature. It should be clear  
of both cold draughts and the direct path of warm air  
from the heater.  
External controls must have the same constant  
230 V 50 Hz supply.  
10.2.3 Remote Frost Thermostat  
When required, connect to terminals 2 and 3 in the  
main terminal block.  
Locate within the heated space adjacent to the most  
vulnerable equipment that requires protection.  
An isolator with a contact separation of at least  
3 mm on all poles must be installed adjacent to, but  
not attached to, the heater to disconnect all supplies  
to the heater and any remote control.  
The final connection to the heater should be made  
by flexible cable or conduit to the main terminal  
block on the inside of the heater using 1 mm2 cable  
on all models.  
See Page 16, Section 10.3 through Page 17, Section  
10.4.  
10.2.4 Remote Fan Controls  
The fan will operate automatically providing there is  
a constant 230 V supply to the main terminals.  
Models  
............................................ Fuse Size  
A switch or control wired between terminals L & 1 in  
the terminal block will allow external control of the  
fan(s).  
The fan may be controlled to operate continuously  
from an external control, with the burner cycling on  
and off, providing that the fan run-on at close down  
is not impaired.  
CTUA (All Models) ........................................... 5 A  
CTUB & CTUC (Models 22-50)...................... 10 A  
CTUB & CTUC (Models 75 - 115).................. 20 A  
CTUD heaters must have the external fan, or its  
control connected to Terminal 1 so that the fan run-  
on function at close down operates correctly.  
WARNING  
Electrical Shock Hazard  
Disconnect electrical power before servicing.  
Failure to follow these instructions can result in  
death or electrical shock.  
10.2 Remote Controls  
The heater is designed to be operated by controls  
installed remote from the heater. See Page 16,  
Section 10.3. through Page 17, Section 10.4.  
15  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
10.3 CTUA Wiring Diagram (Models 22-60)  
IGNITION MODULE  
12 11 10  
9
8
7
6
5
4
3
2
1
Time Delay Relay  
BLUE  
BROWN  
Thermostat Limit  
Thermodisc N/C  
BROWN  
GAS VALVE  
E
N
L
LOCKOUT  
RESET  
BLACK  
NO\P(3) YELLOW  
C\P(1)  
WHITE  
NC\P(2)  
Pressure Switch  
Detail  
E
RUN  
N
L
BLUE  
BLUE  
BROWN  
MAINS FILTER  
LOCKOUT  
SITE WIRING  
IGNITION MODULE  
N
L
1
2
3
7
8
Plug in Connection to Gas Valve  
SENSE  
BLACK  
Honeywell  
S4565C 1017 Control  
IGNITION  
NOTE:  
230 V  
1 Ø  
50 Hz  
If any of the original wire supplied with  
the heater must be replaced, it must be  
replaced with wiring material having a  
temperature rating of at least 105° C  
and 600 volts.  
16  
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SECTION 10: WIRING AND ELECTRICAL INFORMATION  
10.4 CTUA Wiring Diagram (Models 75-115)  
SENSE  
BLACK  
IGNITION  
GREEN/YELLOW  
S 4563 C Honeywell  
Time Delay Relay  
BROWN  
BLUE  
Thermostat Limit  
Thermodisc N/C  
BROWN  
BLUE  
RUN  
E
N
L
E
N
L
LOCKOUT  
E
N
L
PRESSURE SWITCH  
BLACK  
NO\P(3)  
YELLOW  
WHITE  
C \P(1)  
NC\P(2)  
LOCKOUT  
RESET  
SITE WIRING  
Pressure Switch  
Detail  
N
L
1
2
3
7
8
230 V  
1 Ø  
50 Hz  
NOTE:  
If any of the original wire supplied with  
the heater must be replaced, it must be  
replaced with wiring material having a  
temperature rating of at least 105° C  
and 600 volts.  
17  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
10.5 CTUB/C Wiring Diagram (Models 22-40)  
IGNITION MODULE  
12 11 10  
9
8
7
6
5
4
3
2
1
Time Delay Relay  
BLUE  
BROWN  
BROWN  
Thermostat Limit  
Thermodisc N/C  
GAS VALVE  
GREEN/YELLOW  
WHITE N  
HIGH BLACK  
MEDIUM BLUE  
BLACK  
NO\P(3) YELLOW  
LOCKOUT  
RESET  
LOW RED  
C\P(1)  
WHITE  
NC\P(2)  
Pressure Switch  
Detail  
E
RUN  
N
L
BLUE  
BLUE  
BROWN  
MAINS FILTER  
LOCKOUT  
SITE WIRING  
IGNITION MODULE  
N
L
1
2
3
7
8
Plug in Connection to Gas Valve  
SENSE  
BLACK  
Honeywell  
S4565C 1017 Control  
IGNITION  
230 V  
1 Ø  
50 Hz  
NOTE:  
Unused speed setting wires for the  
centrifugal fan must be isolated and  
insulated. If any of the original wire  
supplied with the heater must be  
replaced, it must be replaced with  
wiring material having a temperature  
rating of at least 105° C and 600 volts.  
18  
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SECTION 10: WIRING AND ELECTRICAL INFORMATION  
10.6 CTUB/C Wiring Diagram (Models 50-60)  
IGNITION MODULE  
12 11 10  
9
8
7
6
5
4
3
2
1
Time Delay Relay  
BLUE  
BROWN  
BROWN  
Thermostat Limit  
Thermodisc N/C  
GAS VALVE  
CENTRIFUGAL FAN 2  
GREEN/YELLOW  
WHITE N  
HIGH BLACK  
MEDIUM BLUE  
LOW RED  
BLACK  
LOCKOUT  
RESET  
NO\P(3) YELLOW  
GREEN/YELLOW  
WHITE N  
C\P(1)  
WHITE  
NC\P(2)  
HIGH BLACK  
MEDIUM BLUE  
Pressure Switch  
Detail  
LOW RED  
E
RUN  
CENTRIFUGAL FAN 1  
N
L
A
B
5
8
6
4
RELAY  
BLUE  
9
7
BLUE  
BROWN  
MAINS FILTER  
LOCKOUT  
SITE WIRING  
IGNITION MODULE  
N
L
1
2
3
7
8
Plug in Connection to Gas Valve  
SENSE  
BLACK  
Honeywell  
S4565C 1017 Control  
IGNITION  
NOTE:  
Unused speed setting wires for the  
centrifugal fan must be isolated and  
insulated. If any of the original wire  
supplied with the heater must be  
replaced, it must be replaced with  
wiring material having a temperature  
rating of at least 105° C and 600 volts.  
230 V  
1 Ø  
50 Hz  
19  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
10.7 CTUB/C Wiring Diagram (Models 75-115)  
SENSE  
BLACK  
IGNITION  
Time Delay Relay  
GREEN/YELLOW  
BROWN  
BLUE  
S 4563 C Honeywell  
Thermostat Limit  
Thermodisc N/C  
CENTRIFUGAL FAN 3  
models 100-115 only  
GREEN/YELLOW  
WHITE  
N
HIGH BLACK  
MEDIUM BLUE  
LOW RED  
CENTRIFUGAL FAN 2  
GREEN/YELLOW  
WHITE  
BROWN  
N
HIGH BLACK  
MEDIUM BLUE  
LOW RED  
BLUE  
RUN  
GREEN/YELLOW  
WHITE  
N
HIGH BLACK  
MEDIUM BLUE  
LOW RED  
CENTRIFUGAL FAN  
1
LOCKOUT  
A
5
8
6
4
E
N
L
RELAY  
9
B
7
PRESSURE SWITCH  
BLACK  
NO\P(3)  
YELLOW  
WHITE  
C \P(1)  
NC\P(2)  
LOCKOUT  
RESET  
SITE WIRING  
Pressure Switch  
Detail  
N
L
1
2
3
7
8
NOTE:  
Unused speed setting wires for the  
centrifugal fan must be isolated and  
insulated. If any of the original wire  
supplied with the heater must be  
replaced, it must be replaced with  
wiring material having a temperature  
rating of at least 105° C and 600 volts.  
230 V  
1 Ø  
50 Hz  
20  
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SECTION 10: WIRING AND ELECTRICAL INFORMATION  
10.8 CTUD Wiring Diagram (Models 22-60)  
IGNITION MODULE  
12 11 10  
9
8
7
6
5
4
3
2
1
Time Delay Relay  
BLUE  
BROWN  
BROWN  
Thermostat Limit  
Thermodisc N/C  
GAS VALVE  
BLACK  
NO\P(3) YELLOW  
LOCKOUT  
RESET  
C\P(1)  
WHITE  
NC\P(2)  
Pressure Switch  
Detail  
E
RUN  
N
L
BLUE  
BLUE  
BROWN  
MAINS FILTER  
LOCKOUT  
SITE WIRING  
IGNITION MODULE  
N
L
1
2
3
7
8
Plug in Connection to Gas Valve  
SENSE  
BLACK  
Honeywell  
S4565C 1017 Control  
IGNITION  
230 V  
1 Ø  
50 Hz  
NOTE:  
For external fan wiring,  
See Page 23, Section 10.10.  
If any of the original wire supplied with the  
heater must be replaced, it must be replaced  
with wiring material having a temperature  
rating of at least 105° C and 600 volts.  
21  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
10.9 CTUD Wiring Diagram (Models 75-115)  
SENSE  
BLACK  
IGNITION  
GREEN/YELLOW  
S 4563 C Honeywell  
Time Delay Relay  
BROWN  
BLUE  
Thermostat Limit  
Thermodisc N/C  
BROWN  
BLUE  
RUN  
LOCKOUT  
E
N
L
PRESSURE SWITCH  
BLACK  
NO\P(3)  
YELLOW  
WHITE  
C \P(1)  
NC\P(2)  
LOCKOUT  
RESET  
SITE  
WIRING  
Pressure Switch  
Detail  
N
L
1
2
3
7
8
NOTE:  
For external fan wiring,  
See Page 23, Section 10.10.  
230 V  
1 Ø  
50 Hz  
If any of the original wire supplied with the  
heater must be replaced, it must be replaced  
with wiring material having a temperature  
rating of at least 105° C and 600 volts.  
22  
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SECTION 10: WIRING AND ELECTRICAL INFORMATION  
10.10 CTUD External Motor Alternative Wiring & Optional Thermostat/Time Switch  
Single Phase Motor  
Three Phase Motor  
N L 1 2 3  
with Load over 7 Amps  
N L 1 2 3  
Room  
Thermostat  
Room  
Thermostat  
2A  
2A  
Frost  
Thermostat  
Frost  
Thermostat  
230 V 50 Hz  
Time Switch  
230 V 50 Hz  
Time Switch  
230 V  
Contactor or Relay  
230v  
Contactor or Relay  
Single Phase Motor  
with Load Over 7 Amps  
N
L
400 V 3 Ø  
motor  
Overload protection must  
be provided at the motor  
or contactor.  
230 V 50 Hz  
supply  
Overload protection must  
be provided at the motor  
or contactor.  
RDW 1565  
N L L L  
3
1 2  
400 V 50 Hz  
3 Ø Supply  
23  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 11: COMMISSIONING  
Installation, service, commissioning and annual  
inspection of the heater must be done by a  
contractor qualified in the installation and service of  
gas-fired heating equipment. Read this manual  
carefully before installation, commissioning,  
operation, or service of this equipment. All  
components are accessed via the hinged door  
secured by a ¼ turn latch. Opening the door  
exposes live electrical connections and hot  
components.  
11.1.2 Electrical Checks  
All pre-commission checks must be carried out  
before commissioning the heater.  
1. Check that all site wiring is connected in  
accordance with the appropriate wiring dia-  
grams on Page 16, Section 10.3 through Page  
23, Section 10.10.  
2. Check the correct fuse size is fitted;  
See Page 15, Section 10.1.  
11.2 Gas Supply  
WARNING  
All aspects of the gas installation including the gas  
meter must be inspected, tested for soundness and  
purged in accordance with local and national codes.  
Ensure that the air is fully purged from the heater  
inlet pipe up to the main gas valve inlet test nipple.  
11.3 Mechanical Checks  
Electrical Shock Hazard  
1. Check that the fan(s) are free to run and  
delivery louvres are turned to give required air  
deflection.  
Use extreme caution while commissioning.  
Failure to follow these instructions can result in  
death or electrical shock.  
2. Check that the flue (and air intake for room  
sealed) is installed in accordance with these  
instructions and local regulations.  
11.1 Pre-Commission Checks  
All pre-commission checks must be carried out  
before lighting the heater.  
3. The thermostat limit thermodisc is preset and  
sealed at the factory and is not adjustable.  
Ensure that the heater and all controls are suitable  
for the gas, pressure and electrical supply to which  
they are to be connected.  
11.4 Begin Commissioning  
11.4.1 Before Operating the Heater  
To ensure that all the controls are in safe working  
order, operate the heater for the first time with the  
isolating gas valve turned off.  
11.1.1 Louvres  
Where fitted, the air delivery louvres need to be set  
during commissioning to give the required air  
distribution.  
1. Turn off the gas isolating valve  
2. Using the installed external control, turn on the  
burner. The automatic sequence will now begin  
as described on Page 25, Figure 10.  
WARNING  
There will be no ignition of the burner and lockout  
will occur, which proves the controls are operating  
correctly.  
Cut Hazard  
Turn off gas and electrical supply before maintenance.  
Fan can start automatically at any time.  
Failure to follow these instructions can result in severe  
injury or product damage.  
24  
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SECTION 11: COMMISSIONING  
Figure 10: Automatic Burner Control Box Sequence  
Burner sequence for Honeywell S4563 or S4565C  
START  
CLOSE  
DOWN  
RUN  
Supply 230 V  
Flue Fan  
30 Sec. Purge*  
NO  
NC  
Pressure Switch  
C
P
ts**  
Ignition Spark  
Start Gas Valve  
Flame Signal  
Required Incoming Signals  
Signals Output By Control  
*Purge time begins at pressure switch change over.  
**ts=Safety time (S4563C=3 seconds [alternate 5 seconds]; S4565C=5 seconds)  
If at any stage the flame fails, the control will go to "lockout". The red light will illuminate and the  
control will need to be manually reset before any further start attempt can be made.  
Figure 11: Gas Valve for Heater (Models 22 - 60)  
End View  
Fixing Screw  
Ignition  
Output  
Ignition Control  
(Plugs into Gas Valve)  
Flame  
Probe  
Connection  
Regulator  
(Under Cover)  
12 Cable Connector  
Outlet Pressure  
Inlet Pressure  
Gas Inlet  
25  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
Figure 12: Gas Valve for Heater (Models 75 - 115)  
Plug for  
Main Gas Valve  
Regulator  
(Under Cover)  
Plug for  
Main Safety  
Gas Valve  
Inlet Pressure  
Gas Inlet  
Gas Outlet  
Outlet Pressure  
11.4.2 Commissioning the Gas Valves (all gases)  
11.4.2.1 Check Burner Gas Pressure  
11.5 Combustion Testing  
1. Loosen the screw cover of the outlet (burner)  
pressure test point and connect a manometer.  
The only adjustment to alter combustion  
performance is burner pressure. Combustion quality  
must be tested to prove correct heater operation.  
Incorrect results will indicate faults with the  
2. With the burner firing, measure the pressure on  
the manometer. To adjust the burner pressure, installation or appliance.  
remove the regulator cover from the valve and  
turn the regulator adjustment screw to set the  
required burner pressure as stated in the Tech-  
nical Data Tables for the correct gas and model  
on Page 8, Section 4.4.  
Combustion testing must be carried out with all  
covers in place. The flue gas is sampled in the flue,  
within 1 meter of the heater. The values of CO2  
should be between 6.5% to 8.0% for natural gas and  
7.0% to 9.1% for LPG dependant upon model.  
The CO will be up to 80 ppm (0.008%) dry, air free  
dependant upon model. Temperature rise of the flue  
gases above ambient should be approximately  
NOTE: If the correct burner pressure cannot be  
reached, then check the inlet pressure to the valve,  
with the burner firing. See Technical Data Tables on  
Page 8, Section 4.4 for inlet pressure requirement.  
160° C to 180° C. Seal test hole in flue after testing.  
Pressure Switch:The pressure switch is factory pre-  
set for each model and is not adjustable.  
Do not continue to adjust the regulator if the  
pressure is not changing.  
11.6 Turning Off the Heater  
Set the external controls to the off position and the  
main burner will stop.  
If the inlet pressure is too low to allow correct burner  
pressure setting, then the gas inlet pressure must be  
corrected before completing the commission.  
The fans will run until they are stopped automatically  
by the fan thermostat.  
Check Gas Rate  
Do not use electrical isolator for control of  
heater. Electrical isolator will switch off the fan.  
Heat exchanger could be damaged. Warranty will  
not cover damage to the heat exchanger if  
operated improperly.  
1. After burner pressure adjustment, allow the  
heater to operate for at least 15 minutes and  
then re-check settings.  
2. Remove the manometer and refit all covers to  
the valve and tighten the screw of the outlet  
pressure tap.  
3. Check gas flow rate at gas meter.  
26  
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SECTION 11: COMMISSIONING  
11.7 External Controls  
External controls may include time switch, room  
thermostat and frost thermostat. Operate each  
control to ensure that they function correctly. Set the  
time switch (if fitted) and room thermostat to the  
users’ requirements.  
11.8 Complete the Commissioning  
Ensure that all covers are fitted correctly and all test  
points are properly sealed.  
11.9 Instruction to the User  
Explain the controls of the heater to the user  
including how to turn it on and off, using the controls  
fitted on site.  
Give this manual to the user.  
Ensure that the user is shown and understands the  
importance of maintaining clearances to  
combustibles and the user instructions on Page 28,  
Section 12 through Page 29, Section 12.5 and all  
warnings defined in this manual.  
27  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 12: USER INSTRUCTIONS  
12.1 User Instructions  
12.3 Common User Controls  
The CTU heaters are fully automatic and operate  
from the external controls fitted on site.  
The only user controls at the heater are the:  
12.3.1 Thermostat Limit Thermodisc  
Press to reset  
Burner Lockout Reset Button:  
See Page 28, Section 12.3.2  
Thermostat Limit Thermodisc Reset Button:  
See Page 28, Section 12.3.1  
These are hand reset devices to give further  
protection against fan failure.  
NOTE: To reset, the heat exchanger must be cool.  
WARNING  
Description  
Part Number  
All Models  
90412100  
WARNING  
Electrical Shock Hazard  
Disconnect electrical power before servicing.  
Failure to follow these instructions can result in  
death or electrical shock.  
Explosion Hazard  
If control locks out, do not make more than 3  
12.2 Heater Operation  
attempts to restart the heater.  
When the heater has been switched on by the  
remote controls installed on site, the main burner will  
automatically turn on.  
The burner control box will control the safe ignition  
of the flame.  
All heaters require a constant gas and electricity  
supply which must not be interrupted during the  
normal operation of this heater.  
Dangerous gas mixtures can build up.  
The fault must be traced and repaired by a  
registered installer or service engineer.  
Failure to follow these instructions can result in  
death, injury or property damage.  
12.3.2 Burner Lockout Reset Button  
The red warning light at the front of the heater will  
illuminate when the control has gone to lockout. This  
may be caused by flame failure. Press the reset  
button on the back of the heater, (See Page 5,  
Section 4.1), or the remote reset if installed on site.  
Figure 13: Heater Operating Sequence  
ON  
CLOSE  
DOWN  
THERMOSTAT  
CALL FOR  
HEAT  
ON  
BURNER  
RUN  
12.4 Lighting Instructions  
12.4.1 To Turn On Heater  
ON  
2-3 MINUTES  
RUN ON  
FAN  
1. Ensure that the electrical and gas supplies to  
the heater are on. Check that the on site  
controls are “ON”.  
NOTE: The thermostat setting must be above the  
ambient temperature for the heater to operate.  
2. The green light will be on and the automatic fir-  
ing sequence will begin as described on Page  
25, Figure 10. The heater will now operate auto-  
matically under the control of the on site con-  
trols. Following long shut down periods, the  
control may go to lockout. See Page 28, Sec-  
tion 12.3.2.  
28  
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SECTION 12: USER INSTRUCTIONS  
12.4.2 To Turn the Heater Off  
Set the installed remote controls to the “OFF”  
position.  
The burner will turn off immediately.  
FOR YOUR SAFETY  
If you smell gas:  
1. Open windows.  
The fan will continue to run for a few minutes.  
To restart, turn the control used above to “ON”.  
2. DO NOT try to light any appliance.  
3. DO NOT use electrical switches.  
4. DO NOT use any telephone in  
your building.  
12.5 Simple Fault Finding  
5. Leave the building.  
Some possible reasons for the heater not operating  
are:  
1. Gas supply not turned ON.  
6. Immediately call your local gas  
supplier after leaving the building.  
Follow the gas supplier’s  
instructions.  
7. If you cannot reach your gas  
supplier, call the Fire Department.  
2. Electricity supply not turned ON.  
3. The time and/or temperature controls are not  
“ON”.  
WARNING  
4. The thermostat limit thermodisc may have  
operated. This may be caused by an interrup-  
tion of the electrical supply or failure of the  
distribution fan.  
If the thermostat limit thermodisc persistently  
operates, there is a fault which must be investigated  
by a contractor qualified in the installation and  
service of gas-fired heating equipment.  
Fire Hazard  
Do not store or use petrol or other  
flammable vapours and liquids in the  
vicinity of this or any other appliance.  
12.5.1 Simple Fault Finding (Burner Faults)  
Some objects will catch fire or explode  
when placed close to heater.  
If the burner fails to ignite for any reason, it will go to  
lockout. This will be indicated by the red light on the  
heater or at the remote indicator (if fitted).  
1. Press in and release the lockout reset button. If  
a remote reset is not fitted, a reset button is on  
the rear panel of the heater.  
Failure to follow these instructions can  
result in death, injury or property  
damage.  
See Page 5, Section 4.1.  
Lockout should not occur during normal operation of  
the heater and indicates there is a fault condition  
which must be corrected.  
29  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 13: SERVICING  
13.1 Servicing Instructions  
After commissioning, the heater will require  
13.3 Fan/Motor Assembly Maintenance  
The main fan bearings are permanently sealed and  
maintenance to be carried out annually. If the heater do not need lubrication. Before cleaning, turn off gas  
is used in a dirty or dusty area, more frequent  
maintenance may be necessary.  
Installation, service and annual inspection of  
heater must be done by a contractor qualified  
and electrical supply. Remove the fan(s) and use a  
small brush or duster to clean the fan blades from  
each side. Replace fan(s) when done.  
13.3.1 For CTUB & CTUC Centrifugal Fan  
Models  
in the installation and service of gas-fired heating  
equipment.  
CTUB and CTUC models are fitted with thermally  
protected three speed fans. The number of fans can  
be found on Page 41, Section 16.9 and the standard  
air flow for each model can be found on Page 7,  
Section 4.3.  
WARNING  
For CTUC models, the fans may be accessed via  
the removable panels in the top, bottom and sides of  
the inlet spigot compartment as required.  
Do not operate at higher speeds than the original  
setting on the heater without prior consultation with  
Roberts-Gordon.  
The "HIGH" speed option is available to give the  
normal required air flow against higher static  
Cut Hazard  
Turn off gas and electrical supply before maintenance.  
Fan can start automatically at any time.  
pressures and is not intended to be operated free  
blowing or against low resistance. Use of the fans  
under these conditions may cause the fan thermal  
overload to operate and the fan thermostat to cycle.  
All fans on a heater must be set to operate at the  
same speed. For Models 50 - 115, they will be  
switched using a fan relay built into the heater. See  
Page 40, Section 16.8.2.  
Failure to follow these instructions can result in severe  
injury or product damage.  
NOTE 1: After any maintenance or repair work  
always test fire the heater in accordance with the  
commissioning instructions on Page 24, Section 11  
through Page 27, Section 11.9 to ensure all safety  
systems are in working order before leaving the  
heater to operate. Minor faults may be traced by  
using the troubleshooting charts on Page 32,  
Section 15 through Page 34, Section 15.4.  
13.4 Heat Exchanger Maintenance  
The heat exchanger will remain clean unless a  
problem has developed with combustion. Inspect the  
heat exchanger. Look for signs of overheating at the  
front tubes which may indicate burner over firing or  
persistently low air flows.  
NOTE 2: Check all gas pipes and pipe joints to  
ensure there are no cracks or gas leaks. Any cracks  
in the pipes or pipe joints must be repaired.  
13.5 Gas Control Valve Maintenance  
NOTE 3: Inspect all suspended components and  
hardware. Insure that they are in good condition,  
properly tightened, and corrosion free.  
No regular maintenance is required on these  
devices. To change gas control valves, See Page  
35, Step 16.1 and Page 39, Section 16.5.  
Do not repair or disassemble on site.  
Replace faulty gas valves with genuine  
ROBERTS GORDON® replacement parts.  
13.2 Burner Maintenance  
1. Open the hinged door and remove the burner  
compartment cover. See Page 36, Section  
16.2.  
13.6 Flue Fan  
2. Clean any deposits from the main burner which  
may have formed in the injectors or venturi of  
the burner. See Page 36, Section 16.2.  
The flue fan should not require maintenance.  
However, if the air pressure switch is causing burner  
lockout, then remove the flue fan from the vent box  
by unscrewing the screw at the outlet flange and the  
flue fan mounting plate (See Page 38, Section 16.4).  
Ensure that the fan is free to run and that the fan  
wheel is clean.  
3. Remove the ignition electrode and flame probe.  
Check condition of ignition electrode and flame  
probe. Clean off any deposits which may have  
been formed, check condition of ceramic  
insulators. Replace as necessary.  
30  
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SECTION 14: CONVERSION BETWEEN GASES  
SECTION 14: CONVERSION BETWEEN GASES  
14.1 General  
Conversion between gasses will require a change of  
burner injectors and the gas valve re-commissioning  
to the new conditions.  
14.2 Burner Conversion  
Conversion of the burner assembly from one gas to  
the other is the same for all types of heaters.  
1. Remove the burner compartment cover as  
shown on Page 36, Section 16.2.  
2. Remove the connection between the gas valve  
outlet and the manifold. See Page 35, Section  
16.1 for gas valve removal.  
3. Remove the manifold from the burner assembly  
by removing the screws at the top and bottom.  
See Page 36, Section 16.2.1.  
4. Remove the main burner injectors.  
5. Replace with the injectors for the new gas  
ensuring a gas tight seal.  
6. Refit all components in reverse order.  
14.3 Gas Valves  
All gas valves used on the CTU have pressure  
regulators that may be set to operate on natural gas  
or LPG.  
Conversion is carried out by re-setting the burner  
pressure to the value in the data table during  
commissioning. See Page 8, Section 4.4.  
Ensure that the gas inlet pressure to the heater is  
correct for the new gas, and that the gas supply has  
been purged of the old gas.  
31  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
SECTION 15: TROUBLESHOOTING  
15.1 General  
Installation Code and Annual Inspections: All  
installations and service of ROBERTS  
WARNING  
GORDON® equipment must be performed by a  
contractor qualified in the installation and service  
of equipment sold and supplied by Roberts-  
Gordon and conform to all requirements set forth  
in the ROBERTS GORDON® manuals and all  
applicable governmental authorities pertaining to  
the installation, service and operation of the  
equipment.  
To help facilitate optimum performance and safety,  
Roberts-Gordon recommends that a qualified  
contractor annually inspect your ROBERTS  
GORDON® equipment and perform service  
where necessary, using only replacement parts  
sold and supplied by Roberts-Gordon.  
Explosion Hazard  
Installation must be done by a registered installer/  
contractor qualified in the installation and service of  
gas-fired heating equipment or your gas supplier.  
Failure to follow these instructions can result in death,  
injury or property damage.  
Start  
Are gas & electrical  
No  
Turn on supplies.  
supplies on?  
Yes  
Is Red lockout  
Yes  
No  
Use 15.2 to test burner.  
warning light on?  
No  
Check limt thermostat(s);  
Reset.  
With external controls on,  
does the burner continue  
to fire?  
Use 15.2 to test burner.  
Check for mis-wiring.  
No  
No  
Yes  
Check time delat relay. Is  
there 230 V accross brown  
and blue wires?  
Is distribution air fan  
operating?  
No  
Yes  
Change time delay relay.  
Yes  
If problems persist, contact  
ROBERTS GORDON® at  
Tel: +44(0)121 506 7709  
www.rg-inc.com  
Heater Operating  
TROUBLESHOOT ENDS.  
No  
For your safety and optimum heater performance, use only ROBERTS GORDON® replacement parts.  
Conduct Commissioning procedure as shown on Page 24, Section 11.  
32  
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SECTION 15: TROUBLESHOOTING  
15.2 Troubleshooting For Automatic Ignition Burner Systems  
There are two burner controls used: Honeywell S4563C and  
S4565C. They both have similar operating sequences. To  
measure flame current, connect a 0 - 50 μA DC meter in  
series with the flame probe. If the meter reads negative  
values, then reverse the test leads.  
WARNING  
Electrical Shock Hazard  
Do not touch ignition components.  
Voltage from ignition components is high.  
Start  
Are gas & electrical  
Turn on supplies.  
No  
supplies on?  
Failure to follow these instructions can  
result in death or electrical shock.  
Yes  
Has the thermostat limit  
thermodisc operated or light  
faulty? Reset or replace as  
necessary.  
Is the green light on?  
Are external controls on?  
Yes  
No  
Yes  
No  
Yes  
Press in lockout reset button  
on rear of heater or remote  
reset button if fitted.  
Is red lockout light on?  
No  
Is 230 V supply at fan  
connections?  
Does flue fan run?  
Yes  
Flue fan faulty replace  
No  
Burner control faulty or plug  
in connections faulty. Repair  
or replace as necessary  
Yes  
Check for too much flue/air inlet  
duct. Check for blockage in  
combustion air circuit.  
Check for faulty air pressure  
switch. See section 16.5.  
Does air pressure switch  
change over?  
No  
Yes  
Is HT lead okay and  
Ignition control faulty  
replace.  
Wait 30 - 40 seconds.  
connected?  
No  
No  
Yes  
Yes  
Is ignition spark operating?  
Is spark electrode okay?  
See Section 15.6.  
Yes  
Is the gas valve operating?  
To test valve,  
Replace valve.  
Does the flame light?  
No  
No  
see Section 15.4.  
Yes  
Is the flame current at  
least 1 µAmp DC when  
the flame lights?  
Trace fault in supervision  
system. See Section 16.3.  
Is red lockout light on?  
No  
For your safety and optimum heater performance,  
use only ROBERTS GORDON® replacement parts.  
Conduct Commissioning procedure as shown  
If problems persist, contact  
ROBERTS GORDON® at  
Tel: +44(0) 121 506 7709  
www.rg-inc.com  
Heater Operating  
TROUBLESHOOT ENDS.  
No  
on Page 24, Section 11.  
33  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
15.3 Troubleshooting for Flame Supervision System  
START  
Connect a DC ammeter in  
series with the flame probe.  
Is the green light on and  
Use section 15.1 to  
at least 1 µA DC flame  
current?  
No  
Yes  
Yes  
trace the fault.  
Yes  
Is the connecting lead  
damaged? Is the flame probe  
damaged or touching earthed  
components?  
Is there a current flowing in the  
flame probe circuit with no  
flame present?  
Repair or replace as  
necessary.  
Yes  
Yes  
No  
Is inlet burner gas pressure  
correct? Is live and neutral  
polarity correct? Is  
Does “lockout” occur when  
there is a flame present?  
Control box faulty.  
Replace with correct type.  
flame probe circuit correct?  
No  
Repair or replace as  
necessary.  
No  
If problems persist, contact  
ROBERTS GORDON® at  
Tel: +44(0) 121 506 7709  
www.rg-inc.com  
Heater Operating  
TROUBLESHOOT ENDS.  
No  
NOTE: Minimum flame probe current 1 μA DC. Typical flame probe current 3-5 μA DC.  
15.4 Troubleshooting for Solenoid Valves  
START  
Is 230 V at the valve  
terminals at the  
appropriate time.  
No  
No  
Fault elsewhere  
Fault elsewhere  
Yes  
Is gas pressure at inlet of the  
valve correct for gas type?  
Note pressure found.  
Yes  
Valve faulty.  
Replace with one of  
correct type.  
Does gas pressure at outlet  
of the valve rise when  
valve turns on?  
No  
No  
No  
Yes  
Does gas pressure at  
outlet of valve return to zero or  
lower when valve turns off?  
Valve faulty.  
Replace with one of  
correct type.  
Yes  
If problems persist, contact  
ROBERTS GORDON® at  
Tel: +44(0) 121 506 7709  
www.rg-inc.com  
Valve Operating  
TROUBLESHOOT ENDS.  
34  
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SECTION 16: REMOVAL AND REPLACEMENT PARTS  
SECTION 16: REMOVAL AND REPLACEMENT PARTS  
See warnings and notes on Page 30, Section 13  
before removing or replacing parts.  
Burner Components  
All serviceable burner parts are accessed by the  
door on the right side of the heater. Use a  
screwdriver to turn the latch 90°. See Page 5,  
Section 4.  
16.1 Gas Valve  
Remove the gas supply pipe at the heater inlet.  
16.1.1 Models 22 - 60  
Remove  
fixing  
screw  
Disconnect  
wire harness  
Unplug  
control  
from  
valve  
Ignition  
Control  
Description  
Gas Valve VR4105A  
Ignition Control  
Part Number  
90033403  
90434010  
16.1.2 Models 75 - 115  
Unplug  
electrical lead.  
(rectifier harness)  
Step 1  
Unscrew  
gas pipe  
from the  
valve inlet.  
Ignition  
Control  
Step 2  
Unscrew valve from the  
burner manifold  
or  
unscrew the fixing screws for  
the inlet and outlet flanges.  
Description  
Gas Valve VR4605  
Ignition Control  
Part Number  
90033404  
90434020  
16.1.3 All Models  
Replace in reverse order. Verify that the gas flow  
direction of the valve is correct. Use a minimum  
amount of gas seal on the thread joint. Re-use the  
"O" ring seal in the outlet flange where fitted. Check  
that all the joints are leak free. Reset gas valve. See  
Page 26, Section 11.4.2.  
IT IS IMPORTANT THAT ONLY THE CORRECT  
GAS VALVES SPECIFIED FOR EACH MODEL  
TYPE ARE USED WHEN REPLACING THESE  
CONTROLS.  
35  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
16.2 Burner Compartment  
The burner compartment is a sealed  
compartment. Following any work,  
re-seal the compartment with the gas  
pipe rubber seal fully in place and all  
screws fitted and tight.  
Burner  
compartment  
cover  
Flame probe  
Viewing port  
for flame probe  
Remove flexible  
air duct from spigot  
Ignition electrode  
Viewing port  
for ignition electrode  
Remove  
access plate  
Rubber Seal  
Remove screws and  
pull off burner cover  
16.2.1 Burner Injectors  
Ensure gas tight fitting of injectors.  
Ensure correct alignment with burners.  
Ensure all pipe joints are gas tight.  
Manifold  
Burners  
Injectors  
Remove manifold  
screws and pull  
out manifold  
Manifold  
Unscrew  
Injectors  
Burner  
Screws  
Marking  
CTU-22  
CTU-30  
CTU-35  
CTU-40  
CTU-50  
CTU-60  
CTU-75  
CTU-90  
CTU-100 CTU-115  
Injector Quantity  
5
5
6
7
9
11  
12  
14  
15  
17  
Natural Gas (G20) and (G25)  
Injector size mm Ø  
in Ø  
2.08  
0.0819  
45  
2.25  
0.0886  
225  
2.25  
0.0886  
225  
2.25  
0.0886  
225  
2.25  
0.0886  
225  
2.25  
0.0886  
225  
2.71  
0.1067  
36  
2.71  
0.1067  
36  
2.71  
0.1067  
36  
2.71  
0.1067  
36  
Marking  
RG P/N  
91930045 91930225 91930225 91930225 91930225 91930225 91930036 91930036 91930036 91930036  
LPG Gas Propane (G31) and LPG Gas Butane (G30)  
Injector size mm Ø  
in Ø  
1.25  
0.0492  
125  
1.40  
0.0551  
54  
1.40  
0.0551  
54  
1. 40  
0.0551  
54  
1. 40  
0.0551  
54  
1.35  
0.0531  
135  
1.51  
0.0594  
53  
1.51  
0.0594  
53  
1.51  
0.0594  
53  
1.51  
0.0594  
53  
Marking  
RG P/N  
91930125 91930054 91930054 91930054 91930054 91930135 91930053 91930053 91930053 91930053  
36  
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SECTION 16: REMOVAL AND REPLACEMENT PARTS  
16.3 Ignition Electrode and Flame Probe  
Burners  
Thermostat  
Limit  
Thermodisc  
Flame  
Probe  
Flame  
Probe  
Remove all  
burner compartment  
screws to remove  
the burner  
Remove  
Screw  
compartment and  
access the  
“Front View”.  
Burner Compartment  
Front Views  
Ignition  
Electrode  
Ignition  
Electrode  
.120  
(3 mm)  
spark  
gap  
Burners  
To replace the ignition electrode or flame probe, remove the electrical lead and screw.  
Pull out from mounting. Refit in reverse ensuring that the gap to burner is as shown in the  
front view of the burner compartment.  
Description  
Spark Electrode  
Part Number  
90427411  
Automatic Ignition Flame Probe  
Burners (all models except CTU-40)  
Burners - CTU-40  
90439300  
92000000  
92000001  
37  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
16.4 Flue Fan  
Remove screws securing outlet  
flange to the flue adapter.  
Rear Panel  
Flue Adapter  
to Flue Fan  
screws  
Hole  
Vent Box  
Flue  
Adapter  
Vent Box  
Screws  
Outlet  
Gasket  
Flue Fan  
Disconnect  
electrical connections  
at plug in tabs.  
Remove screws securing flue  
fan mounting plate to vent box.  
Remove screws securing  
mounting plate to fan.  
Vent Box  
Mounting  
Plate  
Refit in reverse.  
Mounting Plate  
to Vent Box  
Screws  
Use new gaskets.  
Ensure sealed joints.  
Ensure mounting plate orifice is  
clear and not obstructed.  
Gasket  
Gasket  
Mounting Plate  
to Flue Fan  
Screws  
Air Plate  
CTU-22  
CTU-30  
CTU-35  
CTU-40  
CTU-50  
CTU-60  
CTU-75  
CTU-90  
CTU-100 CTU-115  
Flue Fan  
Torin DSA Torin DSA Torin DSA Torin DSA Torin DSA Torin DSA AO Smith AO Smith AO Smith Torin DSF  
508-128  
077272  
508-128  
077272  
508-128  
077272  
508-128  
077272  
524-202  
077273  
524-202 JFIG098NS JFIG098NS JFIG098NS 146-052  
077273 077274  
RG P/N  
90710430 90710430 90710430 90710430 90710440 90710440 90710001 90710001 90710001 90710450  
Air mm Ø  
Plate in Ø  
47.6  
1.875  
53.1  
2.09  
60.7  
2.39  
69.1  
2.72  
60.7  
2.39  
69.9  
2.75  
97.0  
3.82  
103.6  
4.08  
110.5  
4.35  
152.4  
6
RG P/N  
11011139  
1101138  
1101140  
11011137  
11011136 11011135 11011134  
11011133  
11011132 11011131  
IT IS IMPORTANT THAT ONLY THE CORRECT FLUE FAN SPECIFIED FOR EACH MODEL TYPE IS  
USED WHEN REPLACING THESE ITEMS.  
Carry out a commission after working on or changing a flue fan. See Page 28, Section 12.  
38  
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SECTION 16: REMOVAL AND REPLACEMENT PARTS  
16.5 Pressure Switch  
Pull off 3 way connector. Spring open plastic clips of  
mounting cradle. Replace with correct type of  
pressure switch for model. The pressure switches  
are colour coded for each pressure setting.  
WARNING  
Carbon Monoxide Hazard  
Use correct pressure switch specified for each model.  
Use of incorrect pressure switch could cause unsafe  
condition.  
Failure to follow these instructions can result in  
death or serious injury.  
Carry out a commission after working on or  
changing a pressure switch. See Page 24, Section  
11.  
CTU-22  
CTU-30 CTU-35 CTU-40  
CTU-50  
CTU-60  
CTU-75  
CTU-90 CTU-100 CTU-115  
RG P/N  
90439801 90439810 90439804 90439803 90439810 90439802 90439811 90439807 90439811 90439807  
Colour  
Code  
pink  
0.57  
0.23  
grey  
0.92  
0.37  
white  
1.17  
grey  
1.02  
0.41  
grey  
0.87  
0.35  
yellow  
0.80  
grey  
1.79  
0.72  
brown  
1.69  
grey  
1.79  
0.72  
brown  
1.69  
Set Point  
mbar  
in wc  
0.47  
0.32  
0.68  
0.68  
39  
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COMBAT® CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL  
16.6 Ignition Control  
• Check that the fan blades are free to rotate  
before turning on the power to the fan.  
IT IS IMPORTANT THAT ONLY THE CORRECT  
IGNITION CONTROL SPECIFIED FOR EACH  
MODEL TYPE IS USED WHEN REPLACING  
THESE ITEMS.  
• Strictly comply with the colour code of the fan  
wires to ensure correct operation. See Page 16,  
Section 10.3 through Page 17, Section 10.4 wir-  
ing diagrams  
16.6.1 S4565C Models 22 to 60  
• Use only genuine ROBERTS GORDON®  
replacement parts.  
This control plugs onto the gas valve. Pull out 12 pin  
electrical connection. Pull out ignition cable and  
flame probe cable noting their positions  
Release screw securing control to gas valve  
16.8 CTUB & CTUC Centrifugal Fan/Guard/Motor  
Assembly  
The direct drive fan/s for the CTUB & CTUC range is  
supplied as a complete assembly. Take careful note  
of the electrical connections of the fan before  
disconnecting from the terminals.  
Refit in reverse. Ensure correct location of ignition  
and flame probe cables. Ensure that the earth  
connection is made directly to the earth point on the  
gas valve.  
For the CTUC versions fitted with an inlet spigot  
assembly, the fans may be accessed through the  
removable covers on the sides, top and bottom of  
the spigot, as required.  
16.6.2 S4563C Models 75 to 115  
This control is mounted at the electrical mounting  
plate. Pull out the 3 cable connectors.  
Pull out ignition cable, ignition earth and flame probe  
cable noting their positions. Remove the screws.  
Refit in reverse. Ensure correct location of ignition  
and flame probe cables.  
16.8.1 Fan Removal and Replacement  
20 mm x 5 mm Adhesive Seal  
is applied to the flange.  
16.7 CTUA Axial Fan/Guard/Motor Assembly  
The axial fan unit for the CTUA heater is  
supplied completely assembled and balanced.  
16.7.1 Fan Removal and Replacement  
Remove the four screws  
and rubber washers.  
Description  
Torin Fan DDC 270-270  
Torin Fan DDC 241-241  
Part Number  
A047  
A049  
Remove the fan by removing the fixing screws while  
supporting the weight of the fan (approx. 19 kg).  
16.8.2 To Replace the Fan(s)  
To reassemble, reverse the procedure shown above.  
• Fit new rubber seal between the fan flange and  
the heater rear panel.  
Description  
Axial Fan 16 in.  
Axial Fan 500 mm.  
Part Number  
90710418  
90710419  
• Fit to the rear panel in the correct orientation as  
shown on Page 41, Figure 14.  
16.7.2 To Replace the Fan Assembly  
• Strictly comply with the colour code of the fan  
wires to ensure correct operation. See Page 18,  
Section 10.5 through Page 20, Section 10.7  
wiring diagrams.  
To replace the fan assembly, reverse the procedure  
shown above. Fit rubber washers to the guard  
mountings to reduce vibration.  
40  
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SECTION 16: REMOVAL AND REPLACEMENT PARTS  
• Use only genuine ROBERTS GORDON®  
replacement parts.  
• Set all fans to operate at the same speed.  
The three speed winding connections are:  
Low speed: White N, Red Live The other two  
windings are "parked" separately in spare terminals.  
Medium speed: White N, Blue live. The other two  
windings are "parked" separately in spare terminals.  
High speed: White N, Black live. The other two  
windings are "parked" separately in spare terminals.  
• Check that the fan blades are free to rotate  
without catching before turning on the power to  
the fan.  
Figure 14: Centrifugal Fan Orientation  
CTUB/C 22-40  
CTUB/C 50-90  
CTUB/C 100-115  
16.9 Fan Data  
CTU-22  
CTU-30  
CTU-40  
CTU-50  
CTU-60  
CTU-75  
CTU-90  
CTU-100  
CTU-115  
Axial Fan Type  
CTUA Models  
EBM  
S4E420  
AA06-02  
EBM  
S4E420  
AA06-02  
EBM  
S4E420  
AA06-02  
Ma-Vib  
V02-C100  
Ma-Vib  
V02-C100  
EBM  
S4E420  
AA06-02  
EBM  
S4E420  
AA06-02  
Ma-Vib  
Ma-Vib  
V02-C100 V02-C100  
RG P/N  
Quantity  
90710418 90710418 90710418 90710419 90710419 90710418 90710418 90710419 90710419  
1
1
1
1
1
2
2
2
2
Fan Rating  
(Watts per Fan)  
160  
160  
160  
370  
370  
160  
160  
370  
370  
Centrifugal Fan Type  
CTUB/C Models  
Torin  
241-241  
Torin  
241-241  
Torin  
241-241  
Torin  
241-241  
Torin  
241-241  
Torin  
270-270  
Torin  
270-270  
Torin  
270-270  
Torin  
270-270  
RG P/N  
Quantity  
A049  
1
A049  
1
A049  
1
A049  
2
A049  
2
A047  
2
A047  
2
A047  
3
A047  
3
Normal Fan Rating (W)  
High Fan Rating (W)  
1100  
1400  
1100  
1400  
1100  
1400  
1100  
1400  
1100  
1400  
1200  
1700  
1200  
1700  
1200  
1700  
1200  
1700  
41  
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SECTION 16: REMOVAL AND REPLACEMENT PARTS  
Attach this information to the wall near the ROBERTS GORDON® heater  
®
Read the Installation, Commissioning, Operation and Service Manual thoroughly before installation, operation or service.  
OPERATING INSTRUCTIONS  
WARNING  
1. STOP! Read all safety instructions on this information sheet.  
2. Open the manual gas valve in the heater supply line.  
3. Turn on electric power to the heater.  
4. Set the thermostat to desired setting (above ambient temperature).  
The automatic starting sequence begins.  
NOTE: Following long shutdown periods, the burner control may go to  
to 'LOCKOUT' during the start sequence. Push the reset button to  
recommence firing. Contact service department if 'LOCKOUT'  
continues (see manual for details).  
TO TURN OFF THE HEATER  
Fire Hazard  
1. Turn the thermostat/time switch to 'OFF'. The burner will turn 'OFF'  
immediately, but fans will continue to cool heat exchanger until the fan  
thermostat switches off.  
Some objects can catch fire or explode when placed  
close to heater.  
IF THE HEATER WILL NOT OPERATE, TO ENSURE YOUR SAFETY,  
FOLLOW THESE INSTRUCTIONS TO SHUT DOWN YOUR HEATER  
Keep all flammable objects, liquids and vapors the  
required clearances to combustibles away from heater.  
1. Set the thermostat to off or the lowest setting.  
2. Turn off electric power to the heater.  
Failure to follow these instructions can result in death,  
injury or property damage.  
3. Turn off the manual gas valve in the heater supply line.  
4. Call your registered installer/contractor qualified in the installation  
and service of gas-fired heating equipment.  
Installation Clearances  
Roof Terminal  
Clearances to Combustibles  
Air  
Intake  
15 cm  
15 cm  
50 cm  
50 cm**  
Flue  
3 m  
Wall  
Terminal  
60 cm  
30 cm  
2.5 - 3.5 m*  
**80 cm is necessary to service heater.  
*Heaters may be mounted at a higher level if destratification  
fans and/or turn down nozzles are installed.  
Roberts-Gordon Europe Limited  
Unit A, Kings Hill Business Park  
Darlaston Road, Wednesbury  
West Midlands WS10 7SH UK  
Telephone: +44(0)121 506 7700  
Fax: +44(0)121 506 7701  
Telephone: 716.852.4400  
Fax: 716.852.0854  
Toll Free: 800.828.7450  
Roberts-Gordon, LLC  
1250 William Street  
P.O. Box 44  
Service Telephone: +44(0)121 506 7709  
Service Fax: +44(0)121 506 7702  
E-mail: [email protected]  
Buffalo, NY 14240-0044 USA  
E-mail: [email protected]  
Installation Code and Annual Inspections:  
All installations and service of ROBERTS GORDON® equipment must be performed by a contractor qualified in the installation and service of equipment sold and supplied by Roberts-Gordon and  
conform to all requirements set forth in the ROBERTS GORDON® manuals and all applicable governmental authorities pertaining to the installation, service and operation of the equipment. To help  
facilitate optimum performance and safety, Roberts-Gordon recommends that a qualified contractor annually inspect your ROBERTS GORDON® equipment and perform service where necessary,  
using only replacement parts sold and supplied by Roberts-Gordon.  
For installations at elevations above 2000' (610 m), the appliance shall be derated 4% for each 1000' (305 m) of elevation above sea level.  
Further Information:Applications, engineering and detailed guidance on systems design, installation and equipment performance is available through ROBERTS GORDON® representatives.  
Please contact us for any further information you may require, including the Installation, Commissioning, Operation and Service Manual.  
These products are not for residential use.  
© 2007 Roberts-Gordon, LLC  
www.rg-inc.com  
Printed in U.S.A.  
P/N 91040028 Rev B  
45  
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