Lochinvar Knight XL 399 800 User Manual
KBX-SER Rev E  
Service Manual  
Models: 399 - 800  
This manual must only be  
used by a qualified heating  
installer / service technician.  
ƽ WARNING  
Read  
all  
instructions,  
including this manual and the  
Knight XL Installation and  
Operation Manual, before  
installing. Perform steps in  
the order given. Failure to  
comply could result in severe  
personal injury, death, or  
substantial property damage.  
Save this manual for future reference.  
Service Manual  
Please read before proceeding  
Installer  
–
Read all instructions,  
When calling or writing about the boiler –  
Please have the boiler model and serial  
number from the boiler rating plate.  
ƽ WARNING  
NOTICE  
including this manual and the Knight XL  
Installation and Operation Manual,  
before installing. Perform steps in the  
order given.  
Consider piping and installation when  
determining boiler location (see the Knight  
XL Installation and Operation Manual).  
User – This manual is for use only by a  
qualified  
heating  
installer/service  
Any claims for damage or shortage in  
shipment must be filed immediately against  
the transportation company by the  
consignee.  
technician. Refer to the Knight XL User’s  
Information Manual for your reference.  
Have this boiler serviced/inspected by a  
qualified service technician at least  
annually.  
Failure to comply with the above could  
result in severe personal injury, death or  
substantial property damage.  
Handling ceramic fiber materials  
REMOVAL OF COMBUSTION CHAMBER LINING  
The combustion chamber door insulation in this product contains ceramic fiber material. Ceramic fibers  
can be converted to cristobalite in very high temperature applications. The International Agency for  
Research on Cancer (IARC) has concluded, “Crystalline silica inhaled in the form of quartz or cristobalite  
from occupational sources is carcinogenic to humans (Group 1).”:  
ƽ WARNING  
ꢀ
Avoid breathing dust and contact with skin and eyes.  
• Use NIOSH certified dust respirator (N95). This type of respirator is based on the OSHA  
requirements for cristobalite at the time this document was written. Other types of respirators may  
be needed depending on the job site conditions. Current NIOSH recommendations can be found on  
the NIOSH website at http://www.cdc.gov/niosh/homepage.html. NIOSH approved respirators,  
manufacturers, and phone numbers are also listed on this website.  
• Wear long-sleeved, loose fitting clothing, gloves, and eye protection.  
ꢀ
ꢀ
ꢀ
Apply enough water to the combustion chamber lining to prevent airborne dust.  
Remove the combustion chamber lining from the boiler and place it in a plastic bag for disposal.  
Wash potentially contaminated clothes separately from other clothing. Rinse clothes washer  
thoroughly.  
NIOSH stated First Aid.  
ꢀ
ꢀ
Eye: Irrigate immediately.  
Breathing: Fresh air.  
3
Service Manual  
Please read before proceeding  
When servicing boiler –  
• To avoid electric shock, disconnect electrical supply  
before performing maintenance.  
• To avoid severe burns, allow boiler to cool before  
performing maintenance.  
Boiler operation –  
• Do not block flow of combustion or ventilation air to  
the boiler.  
• Should overheating occur or gas supply fail to shut off,  
do not turn off or disconnect electrical supply to  
circulator. Instead, shut off the gas supply at a location  
external to the appliance.  
• Do not use this boiler if any part has been under water.  
The possible damage to a flooded appliance can be  
extensive and present numerous safety hazards. Any  
appliance that has been under water must be replaced.  
Boiler water –  
• Thoroughly flush the system (without boiler  
connected) to remove sediment. The high-efficiency  
heat exchanger can be damaged by build-up or  
corrosion due to sediment.  
• Do not use petroleum-based cleaning or sealing  
compounds in the boiler system. Gaskets and seals in  
the system may be damaged. This can result in  
substantial property damage.  
• Do not use “homemade cures” or “boiler patent  
medicines”. Serious damage to the boiler, personnel,  
and/or property may result.  
• Continual fresh make-up water will reduce boiler life.  
Mineral buildup in the heat exchanger reduces heat  
transfer, overheats the stainless steel heat exchanger, and  
causes failure. Addition of oxygen carried in by makeup  
water can cause internal corrosion. Leaks in boiler  
piping must be repaired at once to prevent the  
introduction of makeup water.  
Freeze protection fluids –  
• NEVER use automotive antifreeze. Use only inhibited  
propylene glycol solutions which are specifically  
formulated for hydronic systems. Ethylene glycol is  
toxic and can attack gaskets and seals used in hydronic  
systems.  
4
Service Manual  
What is in this manual?  
Service  
Maintenance  
• Service and maintenance schedules  
• Address reported problems  
Near boiler piping  
• Typical system components  
• Inspect boiler area and boiler interior  
• Clean condensate trap  
• Check all piping for leaks  
• Check air openings  
The Knight XL display  
• Display panel readout, buttons and their functions  
• Flue vent system and air piping  
• Check water system  
• Check expansion tank  
Control module inputs  
• Control module inputs and options  
• Check boiler relief valve  
• Inspect ignition electrode  
• Check ignition ground wiring  
• Check all boiler wiring  
• Check control settings  
• Perform start-up and checks  
• Check burner flame  
• Check flame signal  
• Check flue gas temperature  
• General maintenance  
Control module outputs  
• Control module outputs and options  
General  
• How the boiler operates  
• How the control module operates  
• Access modes -- user and installer  
• Sequence of operation -- Domestic Hot Water  
(DHW)/space heating  
• Review with owner  
• Cleaning boiler heat exchanger  
• Oiled bearing circulators  
Control panel menu access  
• Accessing programming mode and locating menus  
(See separate guide covering the interface.)  
Troubleshooting  
Control panel parameter access  
• Accessing and changing parameters from the display panel  
• Troubleshooting table - No display  
• Checking temperature sensors  
• Sensor tables  
• Troubleshooting table - Fault messages displayed on  
boiler interface  
Quick start information -- parameter  
table  
• An index of available adjustments and readouts, where to  
access them and where to find detailed information.  
• Combustion analysis procedure  
• Gas valve adjustment procedure  
Knight XL operation  
• A: General  
• B: Temperature Setting  
• C: Data Logging  
• D: Functions  
• E: DHW Settings  
• F: Outdoor Air Reset Curve  
• G: Anti-cycling  
• H: Control Modes  
• I: Circulation Pumps  
• J: Service Notification  
5
Service Manual  
1 Service  
Near boiler piping  
This piping reference is included to specify the Near Boiler Piping specific to the Knight XL. This piping scheme is important  
for proper operation of the SMART SYSTEM control. See the Knight XL Installation and Operation Manual for more detailed  
piping diagrams.  
FROM  
SYSTEM  
DOMESTIC HOT  
WATER PUMP  
SYSTEM PUMP  
INDIRECT  
DOMESTIC  
HOT WATER  
TO  
SYSTEM  
TANK  
BOILER PUMP  
TO FLOOR  
DRAIN  
6
Service Manual  
1 Service  
(continued)  
The Knight XL display  
• Press to turn boiler off or  
back on  
• Press to select a menu item  
• Press after parameter programming  
to store parameter data  
• Press to exit Service Mode  
• Hold 5 seconds to enter code  
Input Mode (Menu Mode)  
• Press to move up one level  
in Menu Mode or to exit  
Menu Mode  
SHUTDOWN  
ENTER / RESET  
MENU / EXIT  
DISPLAY SCREEN  
SERVICE  
BUTTON  
PC  
CONNECTION  
PORT  
UP  
DOWN  
PREVIOUS  
NEXT  
• Press to toggle display during normal  
operation to show outlet and return  
temperatures, fan speed, and flame  
signal  
• Press to toggle between digits when  
entering access code or between hour,  
minutes, etc., when entering date and  
time  
• Press to change boiler water  
temperature set point during  
normal operation  
• Press to change displayed data  
values in Menu Mode  
• Press to navigate through menu  
listing in Menu Mode  
7
Service Manual  
1 Service  
Control inputs  
GAS PRESSURE SWITCH  
(OPTIONAL)  
DHW THERMOSTAT  
(OPTIONAL)  
ROOM THERMOSTAT /  
ZONE CONTROL  
LOW VOLTAGE  
CONNECTION  
BOARD  
FLOW SWITCH  
SYSTEM SENSOR  
DHW TANK SENSOR  
(OPTIONAL)  
OUTDOOR SENSOR  
(OPTIONAL)  
SEQUENCER / BUILDING  
MANAGEMENT SYSTEM  
(OPTIONAL)  
LOW WATER CUTOFF  
(OPTIONAL)  
SMART CONTROL  
MODULE  
INLET TEMPERATURE  
SENSOR  
OUTLET TEMPERATURE  
SENSOR  
FLUE GAS SENSOR  
AIR PRESSURE SWITCH  
HIGH LIMIT  
FLAME SENSOR  
BLOCKED DRAIN SWITCH  
DISPLAY PANEL  
PC INTERFACE  
(OPTIONAL)  
8
Service Manual  
1 Service  
(continued)  
Control outputs  
ALARM BELL  
AUX. DEVICE RELAY  
RUN TIME CONTACTS  
LOW VOLTAGE  
CONNECTION  
BOARD  
SEQUENCER / BUILDING  
MANAGEMENT SYSTEM  
BOILER PUMP  
SYSTEM PUMP  
DHW PUMP  
IGNITOR  
BLOWER  
SMART CONTROL  
MODULE  
GAS VALVE  
DISPLAY PANEL  
PC INTERFACE  
9
Service Manual  
1 Service  
General Operation  
Access modes  
How the boiler operates  
User  
The Knight XL uses an advanced stainless steel heat exchanger  
and an electronic control module that allows fully condensing  
operation. The blower pulls in gas and air and pushes flue  
products out of the boiler through the heat exchanger and  
flue piping. The control module regulates blower speed to  
control boiler firing rate. The gas valve senses the amount of  
air flowing into the boiler and allows only the right amount  
of gas to flow.  
The user can adjust space heating set point using the UP and  
DOWN buttons at any time during normal operation. By  
entering the USER code (0704), the user can also change  
temperature units, time and date, and night setback settings.  
In user mode, the following parameters can be viewed but not  
changed: Boiler outlet water temperature in DHW mode;  
boiler model number; software version; total operating hours,  
and total cycles.  
How the control module operates  
Installer  
The Knight XL control module receives input from boiler  
sensors. The control module activates and controls the  
blower and gas valve to regulate heat input and switches  
boiler, DHW and system pumps on and off as needed. The  
user/installer programs the module to meet system needs by  
adjusting control parameters. These parameters set operating  
temperatures and boiler operating modes. Boiler operation  
can be based on boiler outlet water temperature, boiler return  
water temperature or system supply temperature, depending  
on the parameter setting.  
Most parameters are available only to the installer, accessible  
only by entering the installer access code (5309).  
Saving parameters  
To save parameters:  
Press the ENTER/RESET button.  
To keep parameter settings only for a current operating cycle:  
Sequence of operation  
Press the MENU/EXIT button 1 time to return to the  
parameter listings; press again to return to the menu listings.  
Table 1 shows control module normal sequences of operation  
for space heating and DHW operation. The combined  
operation sequence is for a typical application, programmed  
to provide DHW priority.  
10  
Service Manual  
1 Service  
(continued)  
Sequence of operation  
Table 1A Sequence of operation - space heating and DHW  
OPERATION  
DISPLAY  
B
L
R
:
:
S
t
a
n
d
b
y
1. Upon a call for heat, the control turns on the appropriate pumps  
(system and boiler pumps for space heating call; DHW pump  
for DHW call).  
O
U
T
1
2
3
.
8
F
(
1
2
9
)
2. The control connects 120 VAC to the blower. The blower  
does not run at this time.  
B
L
R
:
:
S
t
a
n
d
b
y
(
• The manual reset high limit must be closed and reset.  
• Once the pumps are turned on, the flow switch must close.  
• If the unit is equipped with gas pressure switches, they must  
close.  
• If an auxiliary limit is connected to the unit, it must close.  
• The air pressure switch must be closed.  
O
U
T
1
2
3
.
8
F
1
2
9
)
B
L
R
:
:
P
R
E
P
U
R
G
E
3. The control then starts a 15 second prepurge cycle.  
O
U
T
1
2
3
.
9
F
(
1
2
9
)
4. Once the prepurge cycle is complete, and the blocked drain  
switch is closed, the control starts the 4 second trial for ignition  
by sending spark voltage to the spark electrode and opening  
the gas valve.  
B
L
R
:
I
G
N
I
T
I
O
N
O
U
T
:
1
2
3
.
9
F
(
1
2
9
)
5. If the control does not detect flame before the trial for ignition  
ends, the control will perform a 10 second postpurge. The 399  
model will start another prepurge and trial for ignition. If the  
burner does not light after 4 trials on the 399 model, the control  
will lock out for one hour and then try again.  
B
L
R
:
:
P
O
S
T
P
U
R
G
E
,
9
P
R
E
P
U
R
G
E
O
U
T
1
2
3
.
9
F
(
1
2
)
On the 500 - 800 models, the control will lock out indefinitely  
after the first trial for ignition fails.  
6. If the control detects a flame before the trial for ignition ends, it  
begins to modulate the burner in order to maintain the set point.  
If the boiler lights due to a space heating call for heat, and the  
ramp delay function is active (default is off), the modulation  
will be held to a series of increasing limits after the burner has  
lit.  
B
L
R
:
:
S
H
2
2
0
%
R
A
T
E
O
U
T
1
4
.
8
F
(
1
2
9
)
7. If the space heating call for heat is active, and the DHW  
thermostat or sensor starts a DHW call for heat, the control will  
turn on the DHW pump, wait 2 seconds, and then turn off the  
boiler pump. This will divert the hot water away from the  
heating zone(s) and send it to the DHW tank instead. The  
control will then modulate to maintain the outlet temperature to  
the DHW boiler set point.  
B
L
R
:
:
D
H
W
7
8
5
%
R
A
T
E
O
U
T
1
7
.
8
(
1
8
0
)
11  
Service Manual  
1 Service  
Sequence of operation (continued)  
Table 1A (continued from previous page) Sequence of operation - space heating and DHW  
OPERATION  
DISPLAY  
8. If the boiler is not part of a cascade, and the DHW call for heat  
remains active for more than 30 minutes, and the space heating  
call for heat is also active, then the control will turn on the boiler  
pump, turn off the DHW pump after 2 seconds, and resume  
modulating based on the space heating set point. As long as  
both the space heating and DHW calls for heat remain active,  
the control will switch back and forth between the two modes  
until one of them is satisfied.  
B
L
R
:
:
S
H
2
4
1
%
R
A
T
E
O
U
T
1
3
.
0
F
(
1
2
9
)
9. Once both calls for heat are satisfied, the control will turn off the  
burner. The blower will remain on for the 10 second postpurge  
cycle. Any pumps that are running will continue to run for their  
respective pump delay times, then turn off.  
B
L
R
:
:
P
O
S
T
P
U
R
G
E
2
O
U
T
1
2
7
.
4
F
(
1
9
)
B
L
R
:
:
S
t
a
n
d
b
y
(
10. Boiler pump off, system pump continues its delay if longer.  
11. System pump off.  
O
U
T
1
2
4
.
7
F
1
2
9
)
)
B
L
R
:
S
t
a
n
d
b
y
O
U
T
:
1
2
2
.
9
F
(
1
2
9
12  
Service Manual  
1 Service  
(continued)  
Display panel menu access  
Table 1B Use this procedure to access menus from the display panel  
COMMENTS  
BUTTON  
DISPLAY  
OPERATION  
Boiler turns off (this ensures  
uninterrupted programming)  
B
L
R
:
O
F
F
7
ENTER/RES  
Press 1 time in normal operation  
O
U
T
:
1
2
.
3
º
F
E
n
t
e
r
M
e
n
u
C
o
d
e
:
Digit shown underlined at left will  
flash  
MENU/EXIT  
Hold for 5 seconds -- display will change  
flashing  
0
0
0
0
Press 9 times to change last digit  
in readout to “9”  
E
n
t
e
r
M
e
n
u
C
o
d
e
:
Digit shown underlined at left will  
flash  
UP  
PREVIOUS  
UP  
0
0
0
9
E
n
t
e
r
M
e
n
u
9
C
o
d
e
:
Digit shown underlined at left will  
flash  
Press 2 times to move to the second  
digit  
0
0
0
Digit shown underlined at left will  
flash  
Press 3 times to change second digit  
in readout to “3”  
E
n
t
e
r
M
e
n
u
C
o
d
e
:
0
3
0
9
E
n
t
e
r
M
e
n
u
C
o
d
e
:
Digit shown underlined at left will  
flash  
Press 1 time to change to the first  
digit  
PREVIOUS  
UP  
0
3
0
9
E
n
t
e
r
M
e
n
u
9
C
o
d
e
:
Press 5 times to change first digit  
in readout to “5”  
Digit shown underlined at left will  
flash  
5
3
0
If you enter a digit incorrectly, you can move to the digit by using the NEXT and PREVIOUS buttons  
as needed until the digit you want is flashing. Then use UP and/or DOWN buttons to change the value.  
E
n
t
e
r
M
e
n
u
C
o
d
e
:
The words, “INSTALLER CODE”  
will flash while displayed  
ENTER/RES  
Press to enter the code  
I
N
S
T
A
L
L
E
R
C
O
D
E
After 2 seconds, display shows menus  
(press ENTER/RESET to select a menu)  
>
A
G
e
n
e
r
a
l
The caret symbol, “>” highlights  
the selectable line  
B
T
e
m
p
S
e
t
t
i
n
g
s
If the code is entered incorrectly, the display will return to its previous mode. You will have to start over  
at step 1 to enter the code.  
The caret symbol, “>” highlights  
the selectable line  
A
B
G
e
n
e
r
a
l
e
DOWN  
DOWN  
DOWN  
DOWN  
Press 1 time to highlight second listing  
Press 1 time to toggle menu listing  
>
T
e
m
p
S
t
t
i
n
g
s
>
C
D
a
t
a
c
L
o
g
g
i
n
g
The menu toggles to the next two  
menu options  
D
F
u
n
t
i
o
n
t
s
The menu toggles to the next two  
menu options  
>
E
D
H
W
S
e
t
i
n
g
s
e
Press 2 times to toggle menu listing  
Press 2 times to toggle menu listing  
Press 2 times to toggle menu listing  
F
O
u
t
d
o
o
r
R
e
s
t
s
>
G
A
n
t
i
-
c
y
c
l
i
n
g
The menu toggles to the next two  
menu options  
H
C
o
n
t
r
o
l
M
o
d
e
>
I
C
i
r
c
u
l
a
t
i
o
n
t
P
u
m
p
s
The menu toggles to the next two  
menu options  
DOWN  
J
S
e
r
v
i
c
e
N
o
i
f
i
c
a
t
i
o
n
To select a highlighted menu, press the ENTER/RESET button one time. The display will  
change to the first parameter under that menu, with the first characters flashing.  
13  
Service Manual  
1 Service  
Display panel parameter access  
Table 1C This is a typical example of accessing a parameter, shown for parameter I2, boiler pump delay  
OPERATION  
BUTTON  
DISPLAY  
COMMENTS  
This example shows how to access parameter I2, boiler pump delay. The first display shown is at the beginning  
of the menu listings, after entering the installer acess code.  
>A General  
The caret symbol, “>” highlights  
Beginning of menu listings  
B Temp Settings  
the selectable line  
>A General  
The caret symbol, “>” highlights  
the selectable line  
Press 1 time to highlight second listing  
Press 1 time to toggle menu listing  
DOWN  
DOWN  
B Temp Settings  
>C Data Logging  
The menu toggles to the next two  
menu options  
D Functions  
The menu toggles to the next two  
menu options  
>E DHW Settings  
F Heat Curve  
DOWN  
DOWN  
Press 2 times to toggle menu listing  
Press 2 times to toggle menu listing  
Press 2 times to toggle menu listing  
>G Anti-Cycling  
The menu toggles to the next two  
menu options  
H Control Modes  
I Circulation Pumps  
The menu toggles to the next two  
menu options  
DOWN  
J Service Notification  
I1 Postrun Time  
I1 will flash  
ENTER/RES Press 1 time to list parameters  
System Pump  
I2 Postrun Time SH  
Pump  
I2 will flash  
UP  
Press 1 time to change parameter  
Press 1 time to select parameter  
Press to increase (or decrease) value  
I2 Postrun Time SH  
I2 will stop flashing; parameter  
value will appear  
ENTER/RES  
Pump 0.50 minutes  
I2 Postrun Time SH  
Pump 0.67 minutes  
UP  
(or DOWN)  
Parameter will increase or decrease,  
depending on button pressed  
Press 1 time to save  
(or press MENU/EXIT to continue)  
A General  
Display will change to normal  
display as you exit menu mode  
ENTER/RES  
ENTER/RES  
B Temp Settings  
Press 1 time to return to normal  
operation  
This display example assumes  
a call for space heating is present  
BLR:Pre-Purge  
OUT:123.7ºF  
14  
Service Manual  
1 Service  
(continued)  
Parameter table  
Table 1D This table lists SMART SYSTEM control module parameters and where to access them  
USER ACCESS  
INSTALLER ACCESS  
SEE  
PAGE  
MENU SUB ITEM  
DESCRIPTION  
DISPLAY MODIFY DISPLAY MODIFY  
1
2
3
Boiler Model  
17  
17  
17  
17  
17  
17  
17  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
Yes  
Yes  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
Yes  
Yes  
No  
User Code  
Date and Time  
4
Software Version  
Temperature Units  
Night Setback Temperature  
Night Setback Times  
A
5
6
7
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
1
2
SH Set Point User  
SH Minimum Set Point  
SH Maximum Set Point  
SH Offset  
17  
17  
17  
17  
18  
Yes  
No  
No  
No  
No  
Yes  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
3
B
4
5
SH Differential  
1
2
Hours Running SH  
Hours Running DHW  
Ignition Attempts  
18  
18  
18  
18  
Yes  
Yes  
Yes  
Yes  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
No  
No  
No  
No  
C
3
4
Show Last 10 Errors  
1
Reset Last 10 Errors  
Service Mode Delay  
18  
18  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
D
2
1
DHW Boiler Set Point  
SH/DHW Switching Time  
DHW Tank Set Point  
18  
18  
18  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
2
Yes  
Yes  
E
3
1
2
3
4
Minimum Air Temperature  
Maximum Air Temperature  
Maximum SH Set Point  
Minimum SH Set Point  
Outdoor Air Shutdown  
18  
19  
19  
19  
19  
19  
19  
20  
20  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
No  
No  
No  
5
Yes  
Yes  
No  
Yes  
Yes  
No  
F
Outdoor Air Shutdown  
Differential  
6
7
8
9
Shift Air Reset  
Boost Temperature  
Boost Time  
Yes  
Yes  
Yes  
Yes  
15  
Service Manual  
1 Service  
Parameter table (continued)  
Table 1D (continued from previous page) This table lists SMART SYSTEM control module parameters and  
where to access them  
USER ACCESS  
INSTALLER ACCESS  
SEE  
PAGE  
MENU SUB ITEM  
DESCRIPTION  
DISPLAY MODIFY DISPLAY MODIFY  
1
Anti-cycling Time  
20  
20  
20  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Return Temperature Differential  
for Ending Anti-Cycling  
2
G
3
Ramp Delay On/Off  
SH Controlling Sensor  
(Outlet/System, Inlet)  
SH Source (Thermostat, BMS,  
and Cascade)  
1
2
3
21  
21  
21  
21  
22  
22  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Boiler Cascade Address  
Max. Cascade Set Point  
Cascade Offset  
H
4
5
6
Cascade Differential  
1
System Pump Delay  
SH Pump Delay  
22  
22  
22  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
2
I
3
DHW Pump Delay  
1
2
Service Notification in Month  
22  
22  
22  
22  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Service Notification Running  
Hours  
J
3
Service Notification Boiler Cycles  
4
Reset Service Notification Counter  
The parameters for Building Management System operation are not listed in this table. They are only  
accessible using the PC interface software. See separate documentation for access information. See page  
21 of this manual for a brief discussion.  
NOTICE  
16  
Service Manual  
1 Service  
Viewable and changeable control parameters  
Before changing parameters, note the Night setback times  
settings so that the unit can be returned to its  
CAUTION  
If parameter A6 is set to anything other than 32°F (0°C), the  
night setback feature becomes active. This will require start and  
stop times to be programmed for the days that reduced  
temperatures are required. These times can be changed by the  
user or the installer by accessing parameter A7. Each day of the  
week (Sunday through Saturday) will have an on and off time.  
original operating parameters.  
A: General  
Boiler model  
The control will display “Knight Boiler” as the model number  
because the same control is used on several models. This will be  
displayed when parameter A1 has been accessed. This parameter  
is not changeable.  
Example: Monday ON: 22:30, Tuesday OFF: 6:45. If you wish  
to skip a day and have no night setback, leave the on and off  
times the same. The default times for each day will be 00:00  
(midnight).  
User code  
The User Code allows the user to access and change a limited  
number of control parameters. The access code can be changed  
by the user or the installer to a code of their choosing. To change  
the code, parameter A2 must be accessed. The default code is  
0704. The code can be changed one digit at a time by using the  
arrow keys on the display.  
B: Temperature settings  
SH set point user  
The SH set point user sets the water temperature set point for  
fixed operation or the maximum temperature set point when  
the outdoor air sensor is used. This parameter can be changed  
by the user or the installer by accessing parameter B1. The  
temperature range of this parameter is 50°F (10°C) to 190°F  
(88°C). The default value is 125°F (52°C).  
Date and time  
The control uses an internal clock for the night setback feature  
and for logging of events. For these features to work correctly,  
the clock must be set when the boiler is first installed or anytime  
the boiler has been powered off for more than 30 days. To set the  
clock, parameter A3 must be accessed. The date and time are  
displayed as “YY:MM:DD W hh:mm”. YY = year, MM = month,  
DD = date, W = day (1 = Sunday, 2 = Monday, etc.), hh = hour  
(24 hour time; 2:00 PM = 14:00), mm = minutes.  
SH minimum set point  
The SH minimum set point sets the minimum water  
temperature set point that can be used for space heating  
operation. The user or installer will not be able to program the  
control with a lower SH set point. This parameter can only be  
changed by the installer by accessing parameter B2. The  
temperature range of this parameter is 32°F (0°C) to 190°F  
(88°C). The default value is 70°F (21°C).  
The internal clock does not adjust for  
NOTICE  
Daylight Savings Time and therefore, will  
require a manual adjustment.  
Software version  
SH Maximum set point  
The software version allows the user to view the software version  
in use by the control. This software controls the operation of the  
boiler. When a new software version becomes available, the  
existing control can be replaced with a new control to update the  
software.  
The SH maximum set point sets the maximum water  
temperature set point that can be used for space heating. The  
user or installer will not be able to program the control with a  
higher SH set point. This parameter can only be changed by the  
installer by accessing parameter B3. The temperature range of  
this parameter is 32°F (0°C) to 190°F (88°C). The default value  
is 185°F (85°C).  
Temperature units  
The control can be configured to display temperature in either  
°C or °F. This parameter can be changed by the user or the  
installer by accessing parameter A5. The default is °F.  
SH Offset  
The SH offset sets how many degrees above set point the  
temperature has to go before the boiler will shut off. This  
parameter can only be changed by the installer by accessing  
parameter B4. The temperature range of this parameter is 0°F  
(0°C) to 54°F (30°C). The default value is 10°F (5°C).  
Night setback temperature  
Once the internal clock has been set correctly, the night setback  
feature can be used to program a lower water temperature set  
point for space heating. This parameter can be changed by the  
user or the installer by accessing parameter A6. The  
temperature range for this parameter is 32°F (0°C) to 140°F  
(60°C). The feature is turned off with a setting of 32°F (0°C).  
The default value is 32°F (0°C).  
17  
Service Manual  
1 Service  
SH Differential  
E: DHW settings  
The SH differential sets how many degrees below the turn off  
temperature the temperature has to go before the boiler will turn  
on. This parameter can only be changed by the installer by  
accessing parameter B5. The temperature range of this  
parameter is 0°F (0°C) to 54°F (30°C). The default value is 20°F  
(11°C).  
DHW boiler set point  
When a DHW call for heat becomes active, the control will use  
the DHW boiler set point to determine the firing rate of the  
boiler based on the actual water temperature. This parameter  
can be changed by the installer by accessing parameter E1. The  
temperature range of this parameter is 50°F (10°C) to 190°F  
(88°C). The default value is 180°F (82°C).  
C: Data logging  
SH/DHW switching time  
Hours running SH  
The SH/DHW switching time parameter sets the length of time  
the control will stay in DHW Mode when a SH call has been  
received. After this time period has expired the control will  
revert to SH Mode. If a DHW call is still active the timer will  
reset. After the time period has expired the control will revert  
back to DHW Mode. This will continue until one of the  
demands has been satisfied. This parameter can be changed by  
the installer by accessing parameter E2. The time range of this  
parameter is 10 minutes to 240 minutes. The default value is 30  
minutes.  
The hours running SH parameter shows the total number of  
hours the boiler has been in the SH firing position. This  
parameter can be viewed by the user and the installer by  
accessing parameter C1.  
Hours running DHW  
The hours running DHW parameter shows the total number of  
hours the boiler has been in the DHW firing position. This  
parameter can be viewed by the user and the installer by  
accessing parameter C2.  
DHW tank set point  
Ignition attempts  
By installing a tank sensor, the SMART SYSTEM control can  
perform the tank thermostat function. The SMART SYSTEM  
control automatically detects the presence of this sensor, and  
generates a DHW call for heat when the tank temperature drops  
6°F (3.5°C) below the tank set point, and finishes the call for  
heat when the tank temperature goes 4°F (2°C) above the tank  
set point. This parameter can be changed by the installer by  
accessing parameter E3. The temperature range of this  
parameter is 32°F (0°C) to 212°F (100°C). The default value is  
125°F (52°C).  
The ignition attempts parameter shows the total number of  
times the boiler has attempted to fire. This parameter can be  
viewed by the user and the installer by accessing parameter C3.  
Show last 10 errors  
The control will log the 10 most current errors with the date and  
time the error occurred. This parameter can be viewed by the  
user and the installer by accessing parameter C4.  
D: Functions  
Reset last 10 errors  
F: Outdoor air reset  
The reset last 10 errors parameter allows the error counter to be  
reset to 0. This parameter can only be cleared by the installer by  
accessing parameter D1. Once accessed, press the RESET key to  
clear the counter.  
Outdoor air reset operation  
If an outdoor air sensor is installed, the control will calculate the  
water temperature set point based on the outdoor air  
temperature. As the outdoor air temperature drops the water  
temperature set point increases. This feature allows the boiler to  
be more efficient in periods of mild weather, see FIG. 1-1 on  
page 19.  
Service mode delay  
By pressing the pin button on the front of the display for five (5)  
seconds, the control will be placed in Service Mode. This will  
override all other heat demands. The Service Mode allows the  
installer to set the unit to either maximum firing rate or  
minimum firing rate for the purpose of combustion analysis.  
The delay sets the length of time the boiler will stay in the  
Service Mode if no keys have been pressed before going back to  
its original state. This parameter can only be changed by the  
installer by accessing parameter D2. The time range of this  
parameter is 0 to 40 minutes. The default value is 20 minutes.  
Minimum air temperature  
When the outdoor air temperature drops below this point, the  
water temperature will be at its maximum setting (FIG. 1-1).  
However, if the user set point is set lower, the water temperature  
will be limited by the user set point instead. This parameter can  
be changed by the installer by accessing parameter F1. The  
temperature range of this parameter is -30°F (-34°C) to 90°F  
(32°C). The default value is 25°F (-4°C).  
18  
Service Manual  
1 Service  
(continued)  
Figure 1-1 Outdoor Air Reset Curve  
WATER  
TEMPERATURE  
SET POINT  
MAXIMUM  
RESET  
Default = 180°F  
USER  
SET POINT  
Default = 125°F  
MINIMUM  
RESET  
Default = 70°F  
Default = 70°F  
OUTDOOR AIR  
AT MINIMUM RESET  
Default = 25°F  
OUTDOOR  
TEMPERATURE  
OUTDOOR AIR  
AT MAXIMUM RESET  
Outdoor air shutdown  
Maximum air temperature  
When the outdoor air temperature rises to or above this  
point, the water temperature will be at its minimum setting  
(FIG. 1-1). This parameter can be changed by the installer by  
accessing parameter F2. The temperature range of this  
parameter is -30°F (-34°C) to 90°F (32°C). The default value  
is 70°F (21°C).  
When the outdoor temperature rises above this point, the  
control will block all SH demands (DHW demands will still  
be active). This parameter can be changed by the user or the  
installer by accessing parameter F5. The temperature range of  
this parameter is 0°F (-18°C) to 120°F (49°C). The default  
value is 70°F (21°C).  
Maximum SH set point  
Outdoor air shutdown differential  
When the outdoor temperature drops below its minimum  
setting (F1) the water temperature will be at this point, if the  
SH set point is set higher (FIG. 1-1). This parameter can be  
changed by the installer by accessing parameter F3. The  
temperature range of this parameter is 0°F (-18°C) to 190°F  
(88°C). The default value is 180°F (82°C).  
The outdoor air shutdown differential parameter is the  
number of degrees below parameter F5 the outdoor air  
temperature must go before the boiler will respond to a SH  
demand. This parameter can be changed by the user or the  
installer by accessing parameter F6. The temperature range of  
this parameter is 0°F (0°) to 90°F (50°C). The default value is  
10°F (5°C).  
Minimum SH set point  
Shift reset curve  
When the outdoor temperature rises to or above its  
maximum setting (F2) the water temperature will be at this  
point (FIG. 1-1). This parameter can be changed by the  
installer by accessing parameter F4. The temperature range of  
this parameter is 0°F (-18°C) to 190°F (88°C). The default  
value is 70°F (21°C).  
The shift reset curve parameter shifts the actual set point  
above the calculated set point the number of degrees in this  
parameter. This parameter can be changed by the installer by  
accessing parameter F7. The temperature range of this  
parameter is -27°F (-15°C) to 27°F (15°C). The default value  
is 0°F (0°C). This feature will be active if this parameter is set  
to anything other than 0°F (0°C).  
19  
Service Manual  
1 Service  
Boost temperature  
G: Anti-cycling  
If a SH demand lasts longer than the programmed time delay  
setting (F9) and there have been no DHW demands, the  
control will increase the water temperature set point by the  
amount in this parameter. If the SH demand continues  
through another time period, the set point will be increased  
again. This will continue until either the SH demand ends, a  
maximum of 20 increases has occurred, or the maximum set  
point has been reached. Once the SH demand has been  
satisfied the set point will revert back to its calculated setting.  
The boost temperature can be changed by the installer by  
accessing parameter F8. The temperature range of this  
parameter is 0°F (0°C) to 45°F (25°C). The default value is  
0°F (0°C). This feature will be active if this parameter is set to  
anything other than 0°F (0°C).  
Anti-cycling time  
Once a SH demand has been satisfied, a set amount of time  
must elapse before the control will respond to a new SH  
demand. The control will block the new heat demand and  
anti-cycling will be shown in the display until the time has  
elapsed or the water temperature drops below parameter G2.  
This parameter can be changed by the installer by accessing  
parameter G1. The time range for this parameter is 0 minutes  
to 40 minutes. The default value is 1 minute.  
Inlet temperature differential for ending anti-cycling  
The control will bypass the anti-cycling time if the water  
temperature drops too quickly. The control will use the water  
temperature the boiler was at when it shut off as the starting  
point. If the temperature drops below the temperature  
parameter the control will abort anti-cycling and allow the  
boiler to fire. This parameter can be changed by the installer  
by accessing parameter G2. The temperature range of this  
parameter is 0°F (0°C) to 54°F (30°C). The default value is  
10°F (5°C).  
Boost time  
The boost time parameter sets the amount of time that must  
elapse with a SH demand before the water temperature set  
point will be increased. This parameter can be changed by the  
installer by accessing parameter F9. The time range for this  
parameter is 1 minute to 60 minutes. The default value is 20  
minutes.  
Ramp delay on/off  
When the ramp delay on/off parameter is active, the ramp  
delay limits the boiler firing rate when a SH cycle has started.  
There are six (6) limiting steps used to limit temperature  
overshoot and short cycles, see FIG. 1-2 on page 21 of this  
manual. This feature can be turned on or off depending on  
the installation. This parameter can be changed by the  
installer by accessing parameter G3. The control range of this  
parameter is 0 = Off, 1 = Ramp Up Only, and 2 = Ramp Up  
and Ramp Down. The default value is 0.  
When ramp delay is active, additional parameters for ramp  
delay operation will have to be adjusted. These can only be  
accessed by the optional PC software. See the Knight Smart  
System PC Program Instructions Manual for additional ramp  
delay parameter information.  
20  
Service Manual  
1 Service  
(continued)  
Figure 1-2 Ramp Delay Interval  
% RATE  
RAMP 6  
RAMP 5  
RAMP 4  
RAMP 3  
RAMP 2  
RAMP 1  
CALL  
TIME  
5
TIME  
3
TIME  
1
MINUTES  
FOR  
TIME  
4
TIME  
6
TIME  
2
HEAT  
3 - Cascade. The boiler is part of a group of boilers sequenced  
together. The designated Leader boiler determines the total  
output needed from the group based on the set point and  
controlling sensor reading. It assigns portions of this output  
to itself (Leader) and the Member boilers. When Cascade is  
selected, each boiler in the group requires a unique address  
(see below). The default control is Thermostat.  
H: Control modes  
SH controlling sensor  
The SH controlling sensor parameter selects the sensor the  
control will use to regulate the boiler firing rate. This  
parameter is adjustable by the installer by accessing  
parameter H1. The sensor selections are as follows: The  
outlet sensor regulates the firing rate based on the outlet  
water temperature of the boiler and the inlet sensor regulates  
the firing rate based on the inlet water temperature of the  
boiler. If the outlet sensor is selected, and the optional system  
supply sensor is connected, the control will regulate the firing  
rate based on the system supply sensor temperature. The  
default sensor is the Outlet Sensor.  
Boiler cascade address  
The boiler designated as the Leader needs to be programmed  
with address 0. All the Member boilers require addresses  
from 1 to 7, and the addresses must be different for each  
Member. The addresses can be in any order, regardless of the  
order in which the units are wired together. This parameter  
is adjustable by the installer by accessing parameter H3. The  
outdoor air (if used) and system supply sensor must be  
connected to the Leader boiler. The default address is 1.  
SH source  
The SH source parameter selects the method used to control  
the modulation of the boiler. This parameter is adjustable by  
the installer by accessing parameter H2. The control methods  
are as follows:  
Max. cascade set point  
This parameter determines the set point used by the  
individual boilers in a Cascade. When a boiler is commanded  
to fire by the Leader boiler, it will attempt to achieve this  
temperature at its outlet. The Leader boiler will limit the  
modulation of the last boiler to fire in order to hold the  
temperature at the system supply sensor to the user set point.  
If any of the boiler outlet temperatures reach the max.  
cascade set point, the boiler will then modulate down on its  
own in order to keep its outlet temperature within the max.  
cascade set point. Therefore, this parameter can be used to  
limit the outlet temperatures of all the boilers in a Cascade.  
Note that this parameter does not apply when the boiler is  
heating an indirect DHW tank. This parameter is adjustable  
by the installer by accessing parameter H4. The default max.  
cascade set point is 185°F (85°C).  
1 - Thermostat. The control modulates the boiler based on  
the user set point and the temperature of the selected  
controlling sensor.  
2 - BMS (Building Management System). The control  
modulates the boiler based on the 0 - 10 VDC signal delivered  
to the appropriate terminals on the connection board. When  
BMS is selected additional parameters for BMS operation  
may need to be adjusted. These can only be accessed by the  
optional PC software. See the Knight Smart System PC  
Program Instructions Manual for additional BMS parameter  
information.  
21  
Service Manual  
1 Service  
Service notification running hours  
Cascade offset  
When the boiler control determines that a scheduled service is  
due based on the hours of actual operation, the boiler display  
will alternate the standard boiler display text with the message  
SERVICE DUE every 5 seconds. This parameter is adjustable  
by the installer by accessing parameter J2. The time range for  
this parameter is 0 hours to 100,000 hours. The default time  
is 10,000 hours.  
This parameter determines how much the temperature must  
go above set point before the lead boiler will turn off. This  
parameter can be adjusted by the installer by accessing  
parameter H5. The default value is 9.9°F (5°C).  
Cascade off-on differential  
This parameter determines how much the temperature must  
go below the turn off temperature (Set point + Offset) before  
the lead boiler turns on. This parameter can be adjusted by  
the installer by accessing parameter H6. The default value is  
19.8°F (11°C).  
Service notification boiler cycles  
When the boiler control determines that a scheduled service is  
due based on the number of boiler cycles, the boiler display  
will alternate the standard boiler display text with the message  
SERVICE DUE every 5 seconds. This parameter is adjustable  
by the installer by accessing parameter J3. The range for this  
parameter is 0 cycles to 100,000 cycles. The default is 10,000  
cycles.  
I: Circulation pumps  
System pump delay  
The system pump delay parameter sets the length of time the  
system pump (if connected) will run after a SH demand has  
been satisfied. Setting the delay time to 0 will disable the  
pump. This parameter is adjustable by the installer by  
accessing parameter I1. The time range for this parameter is  
0 minutes to 40 minutes. The default time is 30 seconds.  
Reset service notification counter  
Once servicing has been completed, the service notification  
counter should be reset. This parameter can be reset by the  
installer by accessing parameter J4. Once accessed, press the  
RESET key to reset the service notification counter.  
SH pump delay  
The SH pump delay parameter sets the length of time the  
boiler pump will run after a SH demand has been satisfied.  
Setting the delay time to 0 will disable the pump. This  
parameter is adjustable by the installer by accessing  
parameter I2. The time range for this parameter is 0 minutes  
to 40 minutes. The default time is 30 seconds.  
DHW pump delay  
The DHW pump delay parameter sets the length of time the  
DHW pump (if connected) will run after a DHW demand  
has been satisfied. Setting the delay time to 0 will disable the  
pump. This parameter is adjustable by the installer by  
accessing parameter I3. The time range for this parameter is  
0 minutes to 40 minutes. The default time is 30 seconds.  
J: Service Notification  
Service notification in months  
When the boiler control determines that a scheduled service  
is due based on days of installation, the boiler display will  
alternate the standard boiler display text with the message  
SERVICE DUE every 5 seconds. This parameter is adjustable  
by the installer by accessing parameter J1. The time range for  
this parameter is 0 months to 36 months. The default time is  
12 months.  
22  
Service Manual  
2 Maintenance  
Maintenance and annual startup  
Table 2A Service and Maintenance Schedules  
Owner maintenance  
Service technician  
(see the Knight XL User’s Information Manual for  
instructions)  
(see the following pages for instructions)  
General:  
• Address reported problems  
• Check boiler area  
• Inspect interior; clean and vacuum if  
necessary;  
• Check pressure/temperature  
gauge  
Daily  
• Clean condensate trap and fill with fresh  
water  
•Check for leaks (water, gas, flue,  
condensate)  
• Verify flue and air lines in good condition  
and sealed tight  
• Check vent piping  
• Check air piping  
•Check system water pressure/system  
piping/expansion tank  
• Check control settings  
Monthly  
• Check air and vent termination  
• Check ignition and flame sense  
electrodes (sand off any deposits; clean  
and reposition)  
screens  
• Check relief valve  
• Check wiring and connections  
• Check condensate drain system  
• Check automatic air vents  
• Perform start-up checkout and  
performance verification per Section 10  
in the Knight XL Installation and  
Operation Manual.  
• Flame inspection (stable, uniform)  
•Test low water cutoff (if used)  
Periodically  
• Flame signal (at least 10 microamps at  
high fire)  
• Reset button (low water cutoff)  
• Clean the heat exchanger if flue  
temperature is more than 54°F (30°C)  
above return water temperature.  
• Check boiler piping (gas and  
Every  
6 months  
water) for leaks  
If combustion or performance  
indicate need:  
• Operate relief valve  
• Clean heat exchanger  
• Remove and clean burner using  
compressed air only  
•Shut boiler down (unless boiler  
used for domestic hot water)  
End  
• Clean the blower wheel  
of season  
months  
23  
Service Manual  
2 Maintenance  
Follow the Service and maintenance procedures given throughout this manual and in component literature  
shipped with the boiler. Failure to perform the service and maintenance could result in damage to the boiler  
or system. Failure to follow the directions in this manual and component literature could result in severe  
personal injury, death, or substantial property damage.  
ƽ WARNING  
The boiler should be inspected annually only by a qualified service technician. In addition, the maintenance  
and care of the boiler designated in Table 2A and explained on the following pages must be performed to  
assure maximum boiler efficiency and reliability. Failure to service and maintain the boiler and system could  
result in equipment failure.  
ƽ WARNING  
Electrical shock hazard – Turn off power to the boiler before any service operation on the boiler except as  
noted otherwise in this instruction manual. Failure to turn off electrical power could result in electrical  
shock, causing severe personal injury or death.  
ƽ WARNING  
Address reported problems  
Figure 2-1 Condensate Trap  
1. Inspect any problems reported by the owner and correct  
before proceeding.  
RETAINING  
SCREW  
2” PVC CAP WITH  
BLOCKED DRAIN SWITCH  
Inspect boiler area  
1. Verify that boiler area is free of any combustible  
materials, gasoline and other flammable vapors and  
liquids.  
PVC TEE ASSEMBLY  
(FACTORY SUPPLIED)  
2. Verify that air intake area is free of any of the  
contaminants listed in Section 1 of the Knight XL  
Installation and Operation Manual. If any of these are  
present in the boiler intake air vicinity, they must be  
removed. If they cannot be removed, reinstall the air and  
vent lines per this manual and the Knight XL Installation  
and Operation Manual.  
CONDENSATE FROM  
HEAT EXCHANGER  
TO FLOOR  
DRAIN  
Inspect boiler interior  
The condensate trap must be filled with  
water during all times of boiler operation  
to avoid flue gas emission from the  
condensate drain line. Failure to fill the  
trap could result in severe personal injury  
or death.  
1. Remove the front access cover and inspect the interior of  
the boiler.  
ƽ WARNING  
2. Vacuum any sediment from inside the boiler and  
components. Remove any obstructions.  
Clean condensate trap  
1. Inspect the condensate drain line, condensate PVC  
fittings, and condensate trap.  
Check all piping for leaks  
Eliminate all system or boiler leaks.  
ƽ WARNING  
Continual fresh makeup water will reduce  
boiler life. Minerals can build up in  
sections, reducing heat transfer,  
overheating heat exchanger, and causing  
heat exchanger failure. Leaking water may  
also cause severe property damage.  
2. Remove the PVC cap retaining screw from the PVC cap  
(FIG. 2-1).  
3. Remove the 2 inch PVC cap with the switch located at the  
top of the trap (FIG. 2-1).  
4. Remove any sediment in the trap.  
1. Inspect all water and gas piping and verify to be leak free.  
5. Fill with fresh water until the water begins to pour out of  
the drain.  
2. Look for signs of leaking lines and correct any problems  
found.  
6. Replace the cap. Press the cap onto the trap until the cap  
makes contact with the drain.  
3. Check gas line using the procedure found in Section 7 -  
Gas Connections of the Knight XL Installation and  
Operation Manual.  
7. Replace the retaining screw.  
24  
Service Manual  
2 Maintenance  
(continued)  
Safety relief valves should be re-inspected  
AT LEAST ONCE EVERY THREE YEARS,  
by a licensed plumbing contractor or  
authorized inspection agency, to ensure  
that the product has not been affected by  
corrosive water conditions and to ensure  
that the valve and discharge line have not  
been altered or tampered with illegally.  
Certain naturally occurring conditions  
may corrode the valve or its components  
over time, rendering the valve inoperative.  
Such conditions are not detectable unless  
the valve and its components are  
physically removed and inspected. This  
inspection must only be conducted by a  
plumbing contractor or authorized  
inspection agency – not by the owner.  
Failure to re-inspect the boiler relief valve  
as directed could result in unsafe pressure  
buildup, which can result in severe  
personal injury, death, or substantial  
property damage.  
Flue vent system and air piping  
ƽ WARNING  
1. Visually inspect the entire flue gas venting system and air  
piping for blockage, deterioration or leakage. Repair any  
joints that show signs of leakage. Verify that air inlet pipe  
is connected and properly sealed.  
2. Verify that boiler vent discharge and air intake are clean  
and free of obstructions.  
Failure to inspect for the above conditions  
and have them repaired can result in  
severe personal injury or death.  
ƽ WARNING  
Check water system  
1. Verify all system components are correctly installed and  
operational.  
2. Check the cold fill pressure for the system. Verify it is  
correct (must be a minimum of 12 psi (82.7 kPa)).  
3. Watch the system pressure as the boiler heats up (during  
testing) to ensure pressure does not rise too high.  
Excessive pressure rise indicates expansion tank sizing or  
performance problem.  
Following installation, the valve lever  
must be operated AT LEAST ONCE A  
YEAR to ensure that waterways are clear.  
Certain naturally occurring mineral  
deposits may adhere to the valve,  
rendering it inoperative. When manually  
operating the lever, water will discharge  
and precautions must be taken to avoid  
contact with hot water and to avoid water  
damage. Before operating lever, check to  
see that a discharge line is connected to  
this valve directing the flow of hot water  
from the valve to a proper place of  
disposal. Otherwise severe personal injury  
may result. If no water flows, valve is  
inoperative. Shut down the boiler until a  
new relief valve has been installed.  
ƽ WARNING  
4. Inspect automatic air vents and air separators. Remove  
air vent caps and briefly press push valve to flush vent.  
Replace caps. Make sure vents do not leak. Replace any  
leaking vents.  
Check expansion tank  
1. Expansion tanks provide space for water to move in and  
out as the heating system water expands due to  
temperature increase or contracts as the water cools.  
Tanks may be open, closed or diaphragm or bladder type.  
See Section 6 - Hydronic Piping of the Knight XL  
Installation and Operation Manual for suggested best  
location of expansion tanks and air eliminators.  
2. After following the above warning directions, if the relief  
valve weeps or will not seat properly, replace the relief  
valve. Ensure that the reason for relief valve weeping is  
the valve and not over-pressurization of the system due to  
expansion tank waterlogging or undersizing.  
Check boiler relief valve  
1. Inspect the relief valve and lift the lever to verify flow.  
Before operating any relief valve, ensure that it is piped  
with its discharge in a safe area to avoid severe scald  
potential. Read Section 6 - Hydronic Piping of the  
Knight XL Installation and Operation Manual before  
proceeding further.  
25  
Service Manual  
2 Maintenance  
Inspect ignition and flame sense Check burner flame  
electrodes  
1. Inspect flame through observation window.  
1. Remove the ignition and flame sense electrodes from the  
boiler heat exchanger access cover.  
2. If the flame is unsatisfactory at either high fire or low fire,  
turn off boiler and allow boiler to cool down. Remove  
the burner and clean it thoroughly using a vacuum  
cleaner or compressed air. Do not use compressed air to  
clean burner if performed inside a building.  
2. Remove any deposits accumulated on the ignition/flame  
sense electrode using sandpaper. If the electrodes cannot  
be cleaned satisfactorily, replace with new ones.  
3. Remove the burner, reference FIG.’s 2-2 thru 2-4.  
3. Replace ignition/flame sense electrode, making sure  
gasket is in good condition and correctly positioned.  
4. When replacing the burner, ensure gasket is in good  
condition and positioned correctly (FIG.’s 2-2 thru 2-4).  
Check ignition ground wiring  
1. Inspect boiler ground wire from the heat exchanger access  
cover to ground terminal strip.  
Figure 2-2 Burner Assembly - Model 399  
2. Verify all wiring is in good condition and securely  
attached.  
3. Check ground continuity of wiring using continuity  
meter.  
AIR / GAS ARM  
4. Replace ground wires if ground continuity is not  
satisfactory.  
Check all boiler wiring  
1. Inspect all boiler wiring, making sure wires are in good  
condition and securely attached.  
BURNER  
GASKET  
Check control settings  
SCREWS  
(QTY. 5)  
1. Set the SMART SYSTEM control module display to  
Parameter Mode and check all settings. See Section 1 of  
this manual. Adjust settings if necessary. See Section 1 of  
this manual for adjustment procedures.  
Figure 2-3 Burner Assembly - Model 500  
2. Check settings of external limit controls (if any) and  
adjust if necessary.  
Perform start-up and checks  
1. Start boiler and perform checks and tests specified in  
Section 10 - Start-up of the Knight XL Installation and  
Operation Manual.  
AIR / GAS ARM  
2. Verify cold fill pressure is correct and that operating  
pressure does not go too high.  
BURNER  
GASKET  
SCREWS  
(QTY. 5)  
26  
Service Manual  
2 Maintenance  
(continued)  
Cleaning boiler heat exchanger  
Figure 2-4 Burner Assembly - Models 600 - 800  
1. Shut down boiler:  
• Follow the “To Turn Off Gas to Appliance” instructions  
for the boiler in the Knight XL Installation and  
Operation Manual.  
• Do not drain the boiler unless it will be exposed to  
freezing temperatures. If using freeze prevention fluid  
in system, do not drain.  
AIR ARM  
2. Allow time for the boiler to cool to room temperature if  
it has been firing.  
3. Remove the blower assembly (gas air/arm) from the heat  
exchanger access cover. Set bolts aside.  
BURNER  
GASKET  
4. Remove the nuts securing the heat exchanger access cover  
to the heat exchanger and set aside.  
SCREWS  
(QTY. 5)  
5. Remove the heat exchanger access cover, cover gasket(s)  
and chamber insulation assembly.  
The boiler contains ceramic fiber  
Check flame signal  
ƽ WARNING  
materials. Use care when handling these  
materials per instructions on page 3 of this  
manual. Failure to comply could result in  
severe personal injury.  
1. At high fire the flame signal shown on the display should  
be at least 10 microamps.  
2. A lower flame signal may indicate a fouled or damaged  
flame sense electrode. If cleaning the flame sense  
electrode does not improve, ground wiring is in good  
condition, and ground continuity is satisfactory, replace  
the flame sense electrode.  
6. Use a vacuum cleaner to remove any accumulation on the  
boiler heating surfaces. Do not use any solvent.  
7. Finish cleaning using a clean cloth dampened with warm  
water.  
3. See Section 3 - Troubleshooting in this manual for other  
procedures to deal with low flame signal.  
8. Install access cover gasket, chamber insulation assembly  
and cover.  
Review with owner  
9. Secure nuts on the studs. DO NOT overtighten.  
1. Review the Knight XL User’s Information Manual with  
the owner.  
10. Re-install the blower assembly (gas air/arm) using the  
bolts set aside in Step 3.  
2. Emphasize the need to perform the maintenance  
schedule specified in the Knight XL User’s Information  
Manual (and in this manual as well).  
11. Close isolation valves on piping to isolate boiler from  
system. Attach a hose to the boiler drain and flush boiler  
thoroughly with clean water by using purging valves to  
allow water to flow through the water make-up line to the  
boiler.  
3. Remind the owner of the need to call a licensed  
contractor should the boiler or system exhibit any  
unusual behavior.  
12. When the boiler has been flushed, restore boiler to  
operation.  
4. Remind the owner to follow the proper shutdown  
procedure and to schedule an annual start-up at the  
beginning of the next heating season.  
13. Perform start-up and check-out procedures in the Knight  
XL Installation and Operation Manual.  
27  
Service Manual  
3 Troubleshooting  
Label all wires prior to disconnection  
Check control module fuses  
ƽ WARNING  
when servicing controls. Wiring errors  
can cause improper and dangerous  
operation. Always disconnect power to  
the boiler before servicing. Failure to  
comply could result in severe personal  
injury, death, or substantial property  
damage.  
ALWAYS check control module fuses  
before replacing control module or any  
major components (blower, etc.). If one of  
these fuses is blown, it can prevent the  
control module or other components from  
operating.  
NOTICE  
1. Turn OFF the power to the boiler at the external line  
switch.  
Never jumper (bypass) any device except  
for momentary testing as outlined in the  
Troubleshooting chart. Severe personal  
injury, death, or substantial property  
damage can result.  
ƽ WARNING  
2. Remove top access cover.  
3. Remove the control module cover.  
4. Inspect fuses F2, F3, F4, and F5, see FIG 3-1 below.  
Figure 3-1 Control Module Fuses  
Before troubleshooting:  
1. Have the following items:  
a. Voltmeter that can check 120 VAC, 24 VAC, and  
12 VDC.  
F3 - 1.25 AMP FUSE  
MAIN BOARD  
b. Continuity checker.  
c. Contact thermometer.  
F4 - 3.15 AMP FUSE  
GAS VALVE  
2. Check for 120 VAC (minimum 102 VAC to maximum  
132 VAC) to boiler.  
F5 - 5 AMP FUSE  
PUMPS  
3. Make sure thermostat is calling for heat and contacts  
(including appropriate zone controls) are closed. Check  
for 24 VAC between thermostat wire nuts and ground.  
F2 - 3.15 AMP FUSE  
24V SUPPLY  
4. Make sure all external limit controls are installed and  
operating.  
Check the following:  
1. Wire connectors to control module are securely plugged  
in at the module and originating control.  
5. The boiler is shipped with three (3) spare fuses in a plastic  
bag attached to the control module cover.  
2. Gas pressures:  
• Maximum: 14 inches w.c. (3.5 kPa) (natural and LP)  
with no flow (lockup) or with boiler on  
6. If necessary, replace open fuse (F3 is 1.25 amps, F2 and F4  
are 3.15 amps, and F5 is 5 amps).  
• Minimum:  
4
inches w.c. (1.0 kPa) (natural),  
8 inches w.c. (2.0 kPa) (LP) with gas flowing (verify  
during boiler startup)  
Note: Fuses F2 - F5 are all slow blow fuses.  
Do not jumper fuse or replace with any  
ƽ WARNING  
fuse except as specified. Failure to comply  
could result in severe personal injury,  
death, or substantial property damage.  
7. Install control module cover and top access cover after  
fuse inspection.  
8. Restore power to the boiler at the external line switch and  
verify boiler operation (Section 10 - Start-up in the  
Knight Boiler Installation and Operation Manual) after  
completing boiler service.  
28  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3A Troubleshooting Chart - No Display  
FAULT  
CAUSE  
CORRECTIVE ACTION  
- No 120 VAC supplied to unit.  
• Check external line switch, fuse, or breaker.  
• Check position of ON/OFF switch. Turn switch to the  
ON position.  
• Check 120 VAC through the ON/OFF switch.  
• Check wiring harness connection between display  
board and main control board. Connect  
harness at both points.  
No Display  
- No voltage through the switch.  
- Bad display board.  
• Replace switch.  
• Replace board.  
- Bad main control board.  
- Blown fuse.  
• Replace the main control board.  
• Replace fuse F3 on the main control board, see  
page 28 of this manual.  
- Main control board temperature set point • Review temperature setting.  
satisfied.  
- Remote thermostat satisfied.  
• Review remote thermostat setting.  
No Burner  
Operation  
- Outside air temperature above Warm • Check location of outside air sensor.  
Check  
Weather Shutdown (WWSD) set point for  
main control board.  
resistance of outdoor air sensor and compare to Table  
3D on page 30 of this manual.  
- Unit locked out on fault.  
- Ramp delay active.  
• Consult display for specific fault. Refer to fault  
descriptions on page 32 of this manual for corrective  
actions.  
• Check ramp delay parameter settings. Optional PC  
software required.  
• Turn ramp delay feature off. See page 20 of this  
manual for instructions on how to turn this feature off.  
• Check BMS parameter settings.  
software required.  
Optional PC  
Unit Does Not  
Modulate  
Above 50%  
- Boiler controlled by BMS.  
- Flue sensor open.  
• Verify that the flue sensor is located in the flue outlet.  
• Check wiring connections at the flue sensor.  
• Check the resistance of the flue sensor and compare  
to Table 3C on page 30 of this manual.  
29  
Service Manual  
3 Troubleshooting  
Checking temperature sensors  
The boiler temperature sensors (inlet water, outlet water, system water, flue, and outdoor air) are all resistance type devices. The  
following tables show the correct values for the sensors at various temperatures. Use an ohmmeter to read the resistance of the  
sensor at a known temperature. If the resistance of the sensor does not closely match its corresponding table, replace the sensor.  
Table 3B - Inlet/Outlet System Sensor Resistance vs. Temperature  
Temperature  
Resistance  
Temperature  
Resistance  
50  
68  
18,780  
12,263  
8,194  
5,592  
3,893  
2,760  
158  
176  
194  
212  
--  
1,990  
1,458  
1,084  
817  
--  
86  
104  
122  
140  
--  
--  
Table 3C - Flue Temperature Sensor Resistance vs. Temperature  
Temperature  
Resistance  
Temperature  
Resistance  
68  
14,773  
9,804  
6,652  
4,607  
3,252  
2,337  
176  
194  
212  
230  
248  
--  
1,707  
1,266  
952  
726  
560  
--  
86  
104  
122  
140  
158  
Table 3D - Outdoor Air Sensor Resistance vs. Temperature  
Temperature  
Resistance  
Temperature  
Resistance  
-50  
-40  
-30  
-20  
10  
490,813  
336,606  
234,196  
165,180  
118,018  
85,362  
20  
30  
40  
50  
60  
70  
80  
46,218  
34,558  
26,099  
19,900  
15,311  
11,883  
9,299  
0
10  
62,465  
30  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3E Troubleshooting Chart - Noisy System  
FAULT  
CAUSE  
CORRECTIVE ACTION  
- Supply gas problem. Natural gas pressures • Refer to Section 7 - Gas Connections of the Knight  
should be between 4 inches w.c. (1.0 kPa) XL Installation and Operation Manual for detailed  
and 14 inches w.c. (3.5 kPa). LP gas information concerning the gas supply.  
pressures should be between 8 inches w.c.  
(2.0 kPa) and 14 inches w.c. (3.2 kPa).  
- Gas/air mixture problem.  
• Refer to the Gas Valve Adjustment Procedure on  
page 41 of this manual for the proper gas valve setting.  
Verify that the vent/air intake lengths do not exceed the  
maximum listed in the General Venting section of the  
Knight XL Installation and Operation Manual.  
- Dirty/damaged burner.  
• Refer to page 26 in this manual for the burner removal  
and inspection procedure. Clean or replace the burner  
as necessary.  
Noisy  
Operation  
- Low water flow through the heat exchanger. • Refer to Section  
6
-
Hydronic Piping of the  
Knight XL Installation and Operation Manual for  
minimum flow rates. Verify that the boiler is piped in a  
primary/secondary fashion and that the boiler and  
system pump are running on a call for heat.  
- Air in the piping system.  
• Properly purge all air from the piping system.  
- Low system water pressure.  
• Verify system pressure is a minimum of 12 psi  
(82.7 kPa).  
• Replace fuse F5 on the control board, see page 28 of  
this manual.  
- Blown fuse.  
No Pump  
Operation -  
Boiler Pump  
System Pump  
or  
• Replace pump.  
- Faulty pump.  
- Internal fault on control board.  
• Replace main control board.  
• Replace relay.  
DHW Pump  
- Faulty pump relay.  
-System pressure exceeds relief valve • Lower the system pressure below the 50 psi  
setting.  
(344.7 kPa) rating of the supplied relief valve or replace  
the standard relief valve with a higher rated valve up to  
the maximum pressure of the heat exchanger.  
Relief Valve  
Opening  
• Improperly sized expansion tank.  
31  
Service Manual  
3 Troubleshooting  
Table 3F Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
Either the optional manual reset low gas  
pressure switch or the optional manual reset  
high gas pressure switch tripped (not  
available on 399 models).  
• Reset the pressure switches.  
• Measure the supply gas pressure to determine cause  
of failure. Natural gas pressures should be between  
4 - 14 inches w.c. (1.0 - 3.5 kPa) and LP gas  
pressures should be between 8 - 14 inches w.c.  
(2.0 - 3.2 kPa).  
Gas Pressure SW  
(will require a manual  
reset once the condition  
has been corrected.  
• Refer to Section 7 - Gas Connections of the Knight  
XL Installation and Operation Manual for detailed  
information concerning the gas supply.  
Press the RESET button  
on the SMART SYSTEM  
display to reset.)  
• Correct the supply gas pressure if necessary.  
• Check for a loose or misplaced jumper if pressure  
switches are not installed.  
Either the flow switch or the optional low  
water cutoff is not making.  
• Check boiler pump operation on a call for heat.  
• Check for closed valves or obstructions in the boiler  
piping.  
Flow  
Switch/LWCO  
(will require a manual  
reset once condition has  
been corrected. Press  
the RESET button on  
the SMART SYSTEM  
display to reset.)  
• Verify system is full of water and all air has been  
purged from the system.  
• Check for loose or misplaced jumpers if flow switch or  
LWCO is not installed.  
• Replace fuse F2 on the control board, see page 28 of  
this manual.  
Blown fuse.  
The blocked drain switch has detected • Check condensate tube from unit to floor drain for  
Blocked Drain SW  
(will require a manual  
reset once condition has  
been corrected. Press  
the RESET button on  
the SMART SYSTEM  
display to reset.)  
excessive condensate build up inside the  
unit.  
proper installation and obstructions.  
• Inspect condensate trap for blockage. Clean if  
necessary.  
• Check for loose wiring connection at wire harness  
plug.  
• Bad blocked drain switch. Replace switch.  
The flame detector circuit is seeing a flame  
signal while no flame is present.  
• Check supply voltage for proper polarity.  
• Check external wiring for voltage feedback.  
• Check the flame rod and make sure it is clean.  
• Check the internal wiring for bad connections.  
• Replace main control board.  
Flame  
Sequence  
(will require a manual  
reset once the condition  
has been corrected.  
Press the RESET button  
on the SMART SYSTEM  
display to reset.)  
The main control board did not detect the gas  
valve.  
GV/Relay  
Fail  
• Check wiring harness connection at the gas valve and  
at the main control board.  
(will require a manual  
reset once the condition  
has been corrected.  
• Replace the gas valve wire harness.  
Press the RESET button  
on the SMART SYSTEM  
display to reset.)  
• Replace the gas valve.  
• Replace the main control board.  
32  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
The main control board has received a call • The control board will release the call for heat after a  
for heat too quickly after the previous call for  
heat has ended.  
set time period.  
Anti-cycling  
• The control board will release the call for heat if the  
outlet temperature drops too quickly.  
The unit has failed to prove main burner • Inspect spark electrode and associated wiring for  
ignition after four (4) attempts on the 399  
model or one (1) attempt on the 500 - 800  
models. It will require a manual reset before  
attempting to fire again.  
damage and connection. Reference page 26 of this  
manual for removal and cleaning procedures.  
Replace if necessary.  
• Check for proper electrical grounding of the unit.  
• Check incoming supply gas pressure. Natural gas  
pressures should be between 4 - 14 inches w.c.  
(1.0 - 3.5 kPa) and LP gas pressures should be  
between 8 - 14 inches w.c. (2.0 - 3.2 kPa). Refer  
to Section 7 - Gas Connections of the Knight XL  
Installation and Operation Manual for detailed  
information concerning the gas supply.  
• Verify that the plastic hose from the gas valve to the air  
inlet is connected and is not damaged.  
• Verify that the vent/air intake pipes are correctly  
installed and that there are no obstructions.  
• Check for 24 VAC to the gas valve at the 2-pin  
connection on the side of the main control board during  
the ignition attempt. If no voltage is present, replace  
the main control board.  
No Flame Ign  
(will require a manual  
reset once the condition  
has been corrected.  
• If 24 VAC is present at the main control board, check  
the wiring between the main control board and the gas  
valve. Replace the wiring if necessary. Do not  
disconnect the wiring from the gas valve and attempt to  
measure voltage at that point. The main control board  
can detect if the gas valve is not connected and will  
display the Gas Valve Fail fault.  
Press the RESET button  
on the SMART SYSTEM  
display to reset.)  
• If 24 VAC is present, check the outlet of the valve to  
ensure the valve is flowing gas. With a manometer  
connected to the outlet tap of the gas valve, when the  
unit is in the prepurge period, there should be a  
negative pressure present. When the valve is  
energized a change in pressure should occur. If the  
pressure change does not occur, the gas valve is not  
opening. Replace the gas valve.  
• Inspect flame sensor and associated wiring.  
Reference page 26 of this manual for removal and  
cleaning procedures. Replace if necessary.  
• Inspect the burner. Reference page 26 of this manual  
for removal and cleaning procedures. Replace if  
necessary.  
• Replace the main control board.  
33  
Service Manual  
3 Troubleshooting  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
The unit was running and lost the flame • Inspect spark electrode and associated wiring for  
signal. This condition occurred four (4)  
straight times on the 399 model or twice on  
the 500 - 800 models .  
damage and connection. Reference page 26 of this  
manual for removal and cleaning procedures. Replace  
if necessary.  
• Check for proper electrical grounding of unit.  
• Check incoming supply gas pressure. Natural gas  
pressures should be between 4 - 14 inches w.c.  
(1.0 - 3.5 kPa) and LP gas pressures should be  
between 8 - 14 inches w.c. (2.0 - 3.2 kPa).  
Refer to Section 7 - Gas Connections of the Knight  
XL Installation and Operation Manual for detailed  
information concerning the gas supply.  
• Verify that the plastic hose from the gas valve to the air  
inlet is connected and is not damaged.  
• Verify that the vent/air intake pipes are installed  
correctly and there are no obstructions.  
• Check for 24 VAC to the gas valve at the 2-pin  
connection on the side of the main control board during  
the ignition attempt. If no voltage is present, replace the  
main control board.  
No Flame  
Running  
(will require a manual  
reset once the condition  
has been corrected.  
Press the RESET button  
on the SMART  
• If 24 VAC is present at the main control board, check  
the wiring between the main control board and the gas  
valve. Replace the wiring if necessary. Do not  
disconnect the wiring from the gas valve and attempt to  
measure voltage at that point. The main control board  
can detect if the gas valve is not connected and will  
display the Gas Valve Fail fault.  
SYSTEM display to  
reset.)  
• If 24 VAC is present, check the outlet of the valve to  
ensure the valve is flowing gas. With a manometer  
connected to the outlet tap of the gas valve, when the  
unit is in the prepurge period, there should be a  
negative pressure present.  
When the valve is  
energized a change in pressure should occur. If the  
pressure change does not occur, the gas valve is not  
opening. Replace the gas valve.  
• Inspect flame sensor and associated wiring.  
Reference page 26 of this manual for removal and  
cleaning procedures. Replace if necessary.  
• Inspect the burner. Reference page 26 of this manual  
for removal and cleaning procedures. Replace if  
necessary.  
• Replace the main control board.  
34  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
The outlet water temperature has exceeded • Verify that the system is full of water and that all air  
the setting of the high limit.  
has been properly purged from the system.  
• Verify that the boiler is piped properly into the heating  
system. Refer to Section 6 - Hydronic Piping of the  
Knight XL Installation and Operation Manual  
for the proper piping methods for the Knight XL.  
• Check voltage to boiler pump motor on a call for  
heat. If voltage is not present, check wiring back to  
the pump relay.  
Adjustable High  
Limit w/Manual  
Reset  
• Replace the pump relay if necessary.  
• If 120 VAC is present on a call for heat and the boiler  
pump is not operating, replace the pump.  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• If the system pump is a variable speed pump, ensure  
that the system flow is not less than the boiler flow.  
• If operating on either an inlet or system supply sensor,  
check temperature setting of the main control board.  
• If the high limit has tripped, check setting of the  
device.  
• Check resistance of water sensors and compare to  
Table 3B on page 30 of this manual. Replace sensor  
if necessary.  
• Replace high limit.  
The actual fan RPM is 30% lower than what  
is being called for.  
• Vent/air intake lengths exceed the maximum allowed  
lengths. Refer to Section 3 - General Venting of the  
Knight XL Installation and Operation Manual for  
proper lengths.  
Fan Low  
OR  
Fan Speed Low  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• Check for obstruction or blockage in the vent/air  
intake pipes or at terminations.  
• Check the wiring connections at the fan and at the  
main control board.  
• Replace the fan.  
• Replace the main control board.  
Blown fuse.  
• Replace fuse F4 on the control board, see page 28 of  
this manual.  
35  
Service Manual  
3 Troubleshooting  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
• Vent/air intake lengths exceed the maximum allowed  
lengths. Refer to Section 3 - General Venting of the  
Knight XL Installation and Operation Manual for  
proper lengths.  
Fan High  
OR  
Fan Speed High  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• Check for obstruction or blockage in the vent/air  
intake pipes or at terminations.  
The actual fan RPM is 30% higher than what  
is being called for.  
• Check the wiring connections at the fan and at the  
main control board.  
• Replace the fan.  
• Replace the main control board.  
• Check the sensors and their associated wiring.  
Repair or replace the sensor or wiring if damaged.  
Sensor Open  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• Measure the resistance of the sensors and compare  
the resistance to the tables on page 30 of this  
manual.  
Either the inlet water or outlet water  
temperature sensor has been disconnected.  
• Replace the sensor if necessary.  
• Check the sensors and their associated wiring.  
Repair or replace the sensor or wiring if damaged.  
Sensor Shorted  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
Either the inlet water or outlet water • Measure the resistance of the sensors and compare  
temperature sensor has been shorted.  
the resistance to the tables on page 30 of this  
manual.  
• Replace the sensor if necessary.  
Aux. Proving  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• Check function of remote devices.  
An optional remote proving switch is not  
making.  
• Check for loose or misplaced jumper if auxiliary  
proving switch is not installed.  
• Check the tank temperature.  
Sensors equipped with an internal limit (such  
®
as the Lochinvar Squire Indirect Tank), the  
• Repair or replace the sensor wiring if damaged.  
• Replace the sensor if necessary.  
Tank Open  
limit has opened due to temperature (195°F)  
or the sensor has become disconnected.  
36  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
The stack temperature has exceeded the set  
parameters for the boiler.  
• Inspect the heat exchanger. Reference page 27 of  
this manual for the procedure on how to clean the flue  
side of the heat exchanger.  
• Inspect the flue sensor and associated wiring.  
Measure the resistance of the flue sensor and  
compare to Table 3C on page 30 of this manual.  
Replace the sensor if necessary.  
• Verify that the vent/air intake pipes are properly  
installed and that there are no obstructions.  
• Replace the main control board.  
The temperature rise across the heat  
exchanger has exceeded the set parameters  
for the boiler.  
• Verify that the system is full of water and that all air  
has been properly purged from the system.  
• Verify that the boiler is piped properly into the heating  
system. Refer to Section 6 - Hydronic Piping of the  
Knight XL Installation and Operation Manual  
for the proper piping methods for the Knight XL boiler.  
• Check for voltage to the boiler pump motor on a call  
for heat. If voltage is not present, check the wiring  
back to the pump relay. Replace the pump relay if  
necessary.  
Temp O/Shoot  
• If 120 VAC is present on a call for heat and the boiler  
pump is not operating, replace the pump.  
• Verify that the boiler pump is set to the proper speed  
or that the pump is the proper size. Reference  
Section  
6
-
Hydronic Piping of the Knight  
Boiler Installation and Operation Manual for boiler  
pump specifications.  
Outlet water temperature has exceeded the • Verify that the system is full of water and that all air  
maximum outlet water temperature.  
has been properly purged from the system.  
• Verify that the boiler is piped properly into the heating  
system. Refer to Section 6 - Hydronic Piping of the  
Knight XL Installation and Operation Manual  
for the proper piping methods for the Knight XL boiler.  
• Check for voltage to the boiler pump motor on a call  
for heat. If voltage is not present, check wiring back  
to the pump relay. Replace the pump relay if  
necessary.  
• If 120 VAC is present on a call for heat and the boiler  
pump is not operating, replace the pump.  
37  
Service Manual  
3 Troubleshooting  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
Outlet water temperature has exceeded the • Verify that the boiler pump is set to the proper speed  
maximum outlet water temperature.  
or that the boiler pump is the proper size. Reference  
Section 6 - Hydronic Piping of the Knight XL  
Installation and Operation Manual for boiler pump  
specifications.  
Temp O/Shoot  
(continued)  
• Replace the main control board.  
External control is cycling too often.  
• Check set point of the external control.  
• Check the wiring between the external control and the  
unit.  
Rem Ctrl Flt  
• Replace the control.  
After downloading parameters from a laptop,  
the main control board must be reset.  
• Press the ENTER/RESET button on the SMART  
SYSTEM display panel.  
Parameters  
Progr  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
Air pressure switch contacts are open.  
• Check the wiring connections to switch. Wires should  
be connected to the common and normally closed  
terminals.  
APS  
Open  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• Vent/air intake lengths exceed the maximum allowed  
lengths. Refer to Section 3 - General Venting of the  
Knight XL Installation and Operation Manual for  
proper lengths.  
• Check for obstruction or blockage in the vent/air  
intake pipes or at terminations.  
• Check reference hoses connected to the air pressure  
switch for blockage or obstruction.  
• Inspect the burner. Reference page 26 of this manual  
for removal and cleaning procedures. Replace if  
necessary.  
• Inspect the heat exchanger. Reference page 27 of this  
manual for removal and cleaning procedures.  
Replace if necessary.  
• Faulty air pressure switch. Replace switch.  
38  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
While the unit is in Service Mode, the outlet • Establish a heating load to remove the heat from the  
temperature has exceeded 185°F.  
boiler loop.  
• Verify that the system is full of water and that all air  
has been properly purged from the system.  
• Verify that the boiler is piped properly into the heating  
system. Refer to Section 6 - Hydronic Piping of the  
Knight XL Installation and Operation Manual for the  
proper piping methods for the Knight XL boiler.  
Service Blk  
• Check voltage to the boiler pump motor on a call for  
heat. If voltage is not present, check the wiring back  
to the pump relay. Replace the pump relay if  
necessary.  
• If 120 VAC is present on a call for heat and the boiler  
pump is not operating, replace the pump.  
• Verify that the boiler pump is set to the proper speed  
or that the boiler pump is the proper size. Reference  
Section  
6
-
Hydronic Piping of the Knight  
XL Installation and Operation Manual for boiler  
pump specifications.  
120 VAC input to the main control board has  
dropped below 80 VAC.  
• Check 120 VAC supply to the transformer.  
• Check wiring connections at the low voltage terminal  
strip.  
Low 24 VAC  
• Check the wire size/length to remote devices.  
• Replace the transformer.  
The main control board has detected an  
internal fault.  
• Replace the main control board.  
Watch Dog Error  
Write EEProm  
The main control board has detected an  
internal fault.  
• Replace the main control board.  
The main control board has detected an • Replace the main control board.  
internal fault.  
CRC Parameters  
No Error Stored  
The main control board has detected an • Press the ENTER/RESET button on the SMART  
internal fault.  
SYSTEM display panel.  
39  
Service Manual  
3 Troubleshooting  
Combustion Analysis Procedure  
Table 3H Flue Products  
1. Turn the main power off to the boiler by placing the  
“On/Off” switch in the OFF position.  
Natural Gas  
Propane  
CO2  
O2  
CO2  
9.0% - 11%  
O2  
2. Remove the flue temperature sensor from the flue pipe  
connection. Note: Combustion measurements will be  
made at this point.  
8.0% - 10%  
3.0% - 6.5%  
4.1% - 6.9%  
8. Once the combustion analysis is complete, test the safety  
shutoff device by turning the manual shutoff valve to the  
OFF position and ensuring that the boiler shuts down  
and registers an alarm. Open the manual shutoff valve,  
reset the control, and return to Service Mode.  
3. Turn the main power on to the boiler by placing the  
“On/Off” switch in the ON position.  
4. Place the boiler into the active position by pressing the  
SHUTDOWN button on the display board (see page 7)  
until  
B
L
R
:
S
t
a
n
d
b
y
a
p
p
e
a
r
s
i
n
t
h
e
d
i
s
p
l
a
y
w
i
n
d
o
w
.
9. Turn the main power off to the boiler and replace the flue  
temperature sensor into the flue pipe connection.  
5. Locate the pinhole button above the “T” in the Knight  
logo on the display board (see page 7). Press the button  
once and hold for 5 seconds to place the boiler into  
Service Mode. In Service Mode the boiler will fire at  
ignition speed and will then modulate up to full fire.  
10. Place the boiler back into normal operation.  
You must replace the flue gas temperature  
ƽ WARNING  
sensor to prevent flue gas spillage into the  
room. Failure to comply could result in  
severe personal injury, death, or  
substantial property damage.  
6. Remove the flue temperature sensor. Insert the probe  
from a combustion analyzer into the hole left by the  
removal of the flue temperature sensor.  
7. Once the boiler has modulated up to full fire, measure the  
combustion. The values should be in the range listed in  
Table 11 above. The CO levels should be less than  
150 ppm for a properly installed unit.  
If the combustion is not within the specified range,  
reference the chart below for possible causes and  
corrective actions.  
Table 3G Troubleshooting Chart - Combustion Levels  
POSSIBLE CAUSE  
CORRECTIVE ACTION  
• Refer to Section 3 - General Venting of the Knight XL Installation and Operation Manual  
for the proper venting and air intake methods for the Knight XL boiler.  
Vent/Air Intake Length  
or Obstruction  
• Check for obstructions at the vent/air intake terminals.  
• Refer to Section 7 - Gas Connections of the Knight XL Installation and Operation  
Manual for the proper gas supply for the Knight XL boiler.  
Gas Supply Pressure  
Dirty/Damaged Burner  
• Refer to page 26 of this manual for burner removal and cleaning procedures.  
• Replace burner if necessary.  
• Refer to page 41 of this manual for the gas valve adjustment procedure.  
Gas Valve Adjustment  
40  
Service Manual  
3 Troubleshooting  
(continued)  
Gas valve adjustment procedure  
Figure 3-3 Gas Valve Adjustment: Model 500  
If adjustment of the gas valve is deemed necessary, use the  
following procedures: (Note: The procedures below are  
model specific.)  
Under normal operating conditions this  
valve should not need adjusting.  
CAUTION  
Model 399  
Locate the throttle adjustment screw on the top of the gas  
valve, see FIG. 3-2. Using a screwdriver, turn the screw 1/8  
turn counterclockwise to increase CO2 levels or 1/8 turn  
clockwise to decrease CO2 levels. After one adjustment on  
the valve, follow the Combustion Analysis Procedure on  
page 40 of this manual to measure the combustion.  
If combustion is still not within the specified range, repeat  
the procedure. This procedure SHOULD NOT be  
performed more than four (4) times. If after four (4)  
adjustments and the combustion is still not within the  
specified range, revisit the possible causes in Table 3G on  
page 40 or replace the gas valve.  
Models 600 - 800  
Locate the throttle adjustment screw on top of the gas valve,  
see FIG. 3-4. Using an Allen wrench, turn the screw a 1/4 turn  
counterclockwise to increase CO2 levels or a 1/4 turn  
clockwise to decrease CO2 levels. After one adjustment on  
Figure 3-2 Gas Valve Adjustment: Model 399  
the valve, follow the Combustion Analysis Procedure on page  
40 of this manual to measure the combustion.  
THROTTLE ADJUSTMENT  
SCREW  
If combustion is still not within the specified range, repeat the  
procedure. This procedure SHOULD NOT be performed  
more than four (4) times. If after four (4) adjustments and  
the combustion is still not within the specified range, revisit  
the possible causes in Table 3G on page 40 or replace the gas  
valve.  
Figure 3-4 Gas Valve Adjustment: Models 600 - 800  
Model 500  
Locate the throttle adjustment screw on top of the gas valve,  
see FIG. 3-3. Using a screwdriver, turn the screw a 1/4 turn  
counterclockwise to increase CO2 levels or a 1/4 turn  
THROTTLE  
ADJUSTMENT  
SCREW  
(REMOVE BLUE CAP)  
clockwise to decrease CO2 levels. After one adjustment on  
the valve, follow the Combustion Analysis Procedure on  
page 40 of this manual to measure the combustion.  
If combustion is still not within the specified range, repeat  
the procedure. This procedure SHOULD NOT be  
performed more than four (4) times. If after four (4)  
adjustments and the combustion is still not within the  
specified range, revisit the possible causes in Table 3G on  
page 40 or replace the gas valve.  
41  
Service Manual  
4 Notes  
42  
Service Manual  
4 Notes  
43  
Revision Notes: Revision B (ECO #C02407) reflects air pressure  
switch changes, changes made to the Circulation Pumps Section (page  
22) and removal of references to the pocket pc.  
Revision C (ECO #C02545) reflects the addition of references to  
periodic cleaning of screens in vent terminations and safety shutoff  
testing and instructions.  
Revision D (ECO #C02738) reflects the addition of the Gas Valve  
Adjustment Procedure for a 399 model on page 41.  
Revision E (ECO #CO2918) reflects the addition of Tank Sensor Open  
on page 36 along with updating the condensate trap image on page 24.  
.
KBX-SER Rev E  
3/09  

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