Lochinvar KNIGHT 400 801 User Manual
KBXII-SER Rev B  
Service Manual  
Models: 400 - 801  
ƽ WARNING  
This manual must only be used by a  
qualified heating installer / service  
technician. 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 insulation in this appliance 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).” Normal operating temperatures in this  
appliance are below the level to convert ceramic fibers to cristobalite. Abnormal operating conditions would  
have to be created to convert the ceramic fibers in this appliance to cristobalite.  
ƽ WARNING  
The ceramic fiber material used in this appliance is an irritant; when handling or replacing the ceramic  
materials it is advisable that the installer follow these safety guidelines.  
ꢀ
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 appliance 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 Reset  
• G: Anti-cycling  
• H: Control Modes  
• I: Circulation Pumps  
• J: Building Management System (BMS)  
• K: 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.  
DOMESTIC HOT  
WATER PUMP  
INDIRECT  
DOMESTIC  
HOT WATER  
TANK  
DIRT SEPARATOR  
SYSTEM SENSOR  
SYSTEM PUMP  
Y-STRAINER  
(RECOMMENDED)  
BOILER PUMP  
TO FLOOR  
DRAIN  
6
Service Manual  
1 Service  
(continued)  
The Knight XL display  
NAVIGATION DIAL  
The information on the bottom of the display shows the functions of the two SELECT keys (on either corner), and the  
NAVIGATION dial (in the center):  
MENU = Left SELECT Key  
SETPOINTS = NAVIGATION Dial - Pressing Down  
SHDN = Right SELECT Key  
7
Service Manual  
1 Service  
Control inputs  
SYSTEM PUMP SPEED CONTROL  
GAS PRESSURE SWITCH  
DHW THERMOSTAT  
ROOM THERMOSTAT /  
ZONE CONTROL  
LOW VOLTAGE  
CONNECTION  
BOARD  
FLOW SWITCH  
SYSTEM SENSOR  
OUTDOOR SENSOR  
BUILDING MANAGEMENT  
SYSTEM  
LOW WATER CUTOFF  
INLET TEMPERATURE  
SENSOR  
OUTLET TEMPERATURE /  
HI-LIMIT SENSOR  
FLUE GAS SENSOR  
AIR PRESSURE SWITCH  
LOUVER PROVING SWITCH  
FLAME SENSOR  
BLOCKED DRAIN SWITCH  
DISPLAY PANEL  
SMART CONTROL  
MODULE  
PC INTERFACE  
8
Service Manual  
1 Service  
(continued)  
Control outputs  
ALARM BELL  
LOW VOLTAGE  
CONNECTION  
BOARD  
LOUVER RELAY  
RUN TIME CONTACTS  
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  
Access modes  
General Operation  
User  
How the boiler operates  
The user can adjust space heating and tank target  
temperatures by pressing the NAVIGATION dial when  
“ꢀSETPOINTS” is flashing at the bottom of the display. The  
date and time, and the temperature units can also be changed.  
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.  
Installer  
Most parameters are available only to the installer, accessible  
by entering the installer password (5309).  
How the control module operates  
Saving parameters (reference the Parameter Table -  
Table 1-4 on pages 15 - 18 of this manual)  
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.  
Please note that the brackets ([]) denote  
screen status.  
NOTICE  
To save parameters and exit programming:  
Press the RIGHT SELECT [SAVE] key and then press the  
RIGHT SELECT [HOME] key.  
To enter a parameter and continue programming:  
Press the RIGHT SELECT [SAVE] key 1 time to return to the  
parameter listings; press again to return to the menu listings.  
Remember to press the RIGHT SELECT [HOME] key when  
finished programming in order to save the changes made.  
Sequence of operation  
Table 1-1 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)  
Table 1-1 Sequence of Operation  
OPERATION  
DISPLAY  
1. Upon a call for heat, the gas pressure switch(es) must be closed.  
2. Once the gas pressure switch(es) are closed, the control turns  
on the appropriate pumps (system and boiler pumps for space  
heating,  
DHW  
pump  
for  
DHW).  
The flow switch and/or LWCO must close.  
3. The control turns on power to the louver relay.  
The louver proving switch, air pressure switch, and blocked  
drain switch must close.  
4. The control starts a 15 second prepurge cycle by initiating the  
blower.  
5. The control starts a 4 second trial for ignition by firing the spark  
electrode and opening the gas valve.  
6. If flame is not detected within 1 second after the sparking ends,  
the control will perform a 10 second post-purge, then start  
another prepurge cycle and try to light the burner again. On the  
501 and larger models, the control will lock out if this second  
attempt also fails. On the 400 model, the control will perform a  
total of 4 attempts before locking out.  
7. If flame is detected, it holds the firing rate steady for 5 seconds  
to let the flame stabilize, then it begins to modulate the firing rate  
based on a set point or some other command (such as a 0-10V  
BMS signal).  
11  
Service Manual  
1 Service  
Table 1-1 (continued from previous page) Sequence of Operation  
OPERATION  
DISPLAY  
8. If the space heating call for heat is active, and the tank  
thermostat or sensor starts a DHW call for heat, the boiler will  
switch to the DHW mode. If programmed for normal DHW  
operation (not as a zone), the DHW pump will turn on first, then  
the boiler pump will turn off  
2
seconds later.  
This will divert the boiler’s outlet water from the heating system  
and  
send  
it  
to  
the  
tank  
coil  
instead.  
The control will then modulate to maintain the outlet  
temperature to the DHW boiler set point.  
9. If the boiler is not part of a Cascade, and both the space heating  
and DHW calls for heat remain active long enough, the boiler will  
switch back and forth between the two heating modes until one  
of them is satisfied.  
10. Once both calls for heat are satisfied, the control will turn off the  
burner. The blower will continue to run during a 10 second  
postpurge.  
11. Any pumps that are running will continue to run for their  
respective pump delay times before turning off, unless  
programmed  
to  
remain  
on  
continuously.  
A 60 second anti-cycle period will start, which will delay any  
new call for heat until it times out.  
12. In Standby, ready to start a new cycle.  
12  
Service Manual  
1 Service  
(continued)  
Display panel menu access  
Table 1-2 Use this procedure to access menus from the display panel  
SCREEN  
STATUS  
BUTTON  
OPERATION  
DISPLAY  
[SHDN]  
Press the RIGHT SELECT soft key [SHDN].  
[YES]  
Press the LEFT SELECT soft key [YES].  
Press and hold the LEFT SELECT soft key [MENU]  
for five (5) seconds.  
[MENU]  
Rotate the NAVIGATION dial clockwise until 5 is  
displayed (first digit on the left).  
Press the NAVIGATION dial to select the next digit.  
Rotate the NAVIGATION dial clockwise until 3 is  
shown in the display.  
Press the NAVIGATION dial 2 times to move to the  
last digit.  
Rotate the NAVIGATION dial  
counterclockwise until 9 is displayed.  
[SAVE]  
Press the RIGHT SELECT soft key [SAVE].  
Rotate the NAVIGATION dial counterclockwise to  
select a category.  
13  
Service Manual  
1 Service  
Display panel parameter access  
Table 1-3 This is a typical example of accessing a parameter, shown for parameter Temperature Settings, MIN  
SH Setpt  
SCREEN  
STATUS  
BUTTON  
OPERATION  
DISPLAY  
This example shows how to access parameter Temperature Settings. The first display shown is at the beginning  
of the menu listings, after entering the installer access code.  
Rotate the NAVIGATION dial counterclockwise until  
the arrow (>) is next to TEMPERATURE SETTINGS.  
Press the NAVIGATION dial one time.  
Rotate the NAVIGATION dial counterclockwise until  
the arrow (>) is next to MIN SETPT.  
Press the NAVIGATION dial one time.  
Rotate the NAVIGATION dial to the desired  
temperature.  
[SAVE]  
[EXIT]  
Press the RIGHT SELECT soft key [SAVE] one time.  
Press the LEFT SELECT soft key [EXIT] if all desired  
changes have been made.  
[HOME]  
Press the LEFT SELECT soft key [HOME].  
14  
Service Manual  
1 Service  
(continued)  
Parameter table  
Table 1-4 This table lists SMART SYSTEM control module parameters and where to access them  
User Access  
Installer Access  
Sub  
Item  
See  
Page  
Menu  
Description  
Display Modify Display Modify  
1
2
3
4
5
6
7
8
9
Date and Time  
19  
19  
19  
19  
19  
19  
19  
19  
19  
20  
20  
20  
20  
20  
20  
20  
20  
20  
20  
20  
20  
20  
Yes  
No  
Yes  
No  
No  
No  
No  
No  
No  
No  
Yes  
No  
No  
No  
No  
Yes  
No  
No  
Yes  
No  
No  
No  
Yes  
No  
Yes  
No  
No  
No  
No  
No  
No  
No  
Yes  
No  
No  
No  
No  
Yes  
No  
No  
Yes  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
Yes  
No  
Software Version (read only)  
Temperature Units (ºC/ºF)  
SH Night Setback Offset  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
SH Night Setback On Times  
SH Night Setback Off Times  
DHW Night Setback Offset  
DHW Night Setback On Times  
DHW Night Setback Off Times  
A
10 Display Timeout  
1
2
3
4
5
6
7
8
9
SH1 Set Point  
Minimum SH Set Point  
Maximum SH Set Point  
SH1 Offset Set Point  
SH1 Differential Set Point  
SH2 Set Point  
Yes  
Yes  
Yes  
Yes  
No  
Yes  
Yes  
Yes  
Yes  
No  
B
SH2 Offset Set Point  
SH2 Differential Set Point  
SH3 Set Point  
Yes  
Yes  
No  
Yes  
Yes  
No  
10 SH3 Offset Set Point  
11 SH3 Differential Set Point  
12 3-Way Valve Time  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
1
Reset Last 10 Errors  
20  
No  
No  
Yes  
Yes  
C
D
1
2
3
4
Service Mode Delay  
20  
20  
20  
20  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Freeze Protection Pump On  
Freeze Protection Burner On  
Freeze Protection Burner Differential  
15  
Service Manual  
1 Service  
Parameter table  
Table 1-4 (continued from previous page) This table lists SMART SYSTEM control module parameters and where  
to access them  
User Access  
Installer Access  
Sub  
Item  
See  
Page  
Menu  
Description  
Display Modify Display Modify  
1
2
3
4
5
6
7
8
9
DHW Boiler Set Point  
21  
21  
21  
21  
21  
21  
21  
21  
21  
21  
21  
22  
22  
22  
22  
22  
23  
23  
22  
22  
22  
23  
23  
22  
22  
22  
No  
Yes  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
DHW Tank Set Point  
Tank Set Point Differential  
Boiler Set Point Offset  
Boiler Set Point Differential  
SH/DHW Switching Time  
DHW/SH Switching Time  
Tank Minimum Set Point  
Tank Maximum Set Point  
E
10 DHW Type (Normal, Zone)  
11  
1
2
3
4
5
6
7
8
9
Fan Speed Limiting for Indirect DHW Tank  
Low Outdoor Temperature  
High Outdoor Temperature  
SH1 Set Point at Low Outdoor Temp  
SH1 Set Point at High Outdoor Temp  
Outdoor Air Shutdown SH1  
Outdoor Air Shutdown Differential SH1  
Shift Reset Curve SH1  
SH2 Set Point at Low Outdoor Temp  
SH2 Set Point at High Outdoor Temp  
F
10 Outdoor Air Shutdown SH2  
11 Outdoor Air Shutdown Differential SH2  
12 Shift Reset Curve SH2  
13 SH3 Set Point at Low Outdoor Temp  
14 SH3 Set Point at High Outdoor Temp  
15 Outdoor Air Shutdown SH3  
16 Outdoor Air Shutdown Differential SH3  
23  
23  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
17 Shift Reset Curve SH3  
16  
Service Manual  
1 Service  
(continued)  
Parameter table  
Table 1-4 (continued from previous page) This table lists SMART SYSTEM control module parameters and where  
to access them  
User Access  
Installer Access  
Sub  
Item  
See  
Page  
Menu  
Description  
Display Modify Display Modify  
18 Boost Temperature  
19 Boost Time  
Anti-Cycling Time  
23  
23  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
F
1
2
3
4
1
2
3
4
5
6
7
8
9
23  
23  
23  
24  
24  
24  
24  
25  
25  
25  
25  
25  
25  
25  
25  
25  
25  
26  
26  
26  
26  
26  
26  
26  
26  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Anti-Cycling Override Differential  
Ramp Delay (Enable, Disable)  
SH Ramp Delay  
G
Controlling Sensor  
BMS Tstat Input (Active/Inactive)  
BMS (Active/Inactive)  
ModBus (Active/Inactive)  
ModBus T/O (Timeout)  
Cascade Address  
H
Cascade Type (L/L / EFF)  
Max Cascade Outlet Set Point  
Cascade Offset  
10 Cascade Off/On Differential  
11 Min On/Off Time  
12 Min Next On Time  
13 Boiler Size  
1
2
3
4
5
6
7
8
System Pump Delay  
Boiler Pump Delay  
DHW Pump Delay  
Boiler Pump Anti-Seize Delay  
Boiler Pump Min Voltage  
System Pump Type (CFH/WWSD)  
DHW Pump Anti-Seize Delay  
System Pump Anti-Seize Delay  
I
17  
Service Manual  
1 Service  
Parameter table  
Table 1-4 (continued from previous page) This table lists SMART SYSTEM control module parameters and where  
to access them  
User Access  
Installer Access  
Sub  
Item  
See  
Page  
Menu  
Description  
Display Modify Display Modify  
1
2
3
4
5
6
7
8
9
1
2
3
4
5
BMS Type (Power / Set Point)  
Volts at Min  
26  
26  
26  
26  
26  
27  
27  
27  
27  
27  
27  
27  
27  
27  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
Volts at Max  
Rate at Min Volts  
Rate at Max Volts  
J
Set Point at Min Volts  
Set Point at Max Volts  
On Volts  
Off Differential Volts  
Service Notification Months  
Service Notification Running Time  
Service Notification Cycles  
Reset Maintenance Reminder  
Installer Name and Phone Number  
K
18  
Service Manual  
1 Service  
(continued)  
Viewable and changeable control parameters  
Before changing parameters, note the  
settings so that the unit can be returned to  
its original operating parameters.  
Space Heating (SH) and Domestic Hot Water (DHW)  
Night Setback On Times  
CAUTION  
This is the time in which the SH Night Setback Offset becomes  
active. There are 7 start times and 7 stop times each for the  
space heating and DHW night setback features. Both may be set  
to any time within a 7-day week. These settings are referred to  
as triggers. Multiple start or stop triggers may be set within a  
single day, if desired. When a start trigger and a stop trigger are  
set to the same time, the stop trigger has priority. The installer  
may adjust the space heating night setback start triggers by  
accessing parameter A5. The DHW start triggers in parameter  
A8. This screen shows the start trigger number, the day of the  
week, and the time of day.  
A: General  
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 four (4) hours. To set the clock, parameter A1 must be  
accessed.  
The internal clock does not adjust for  
NOTICE  
Please note that the brackets ([]) denote  
Daylight Savings Time and therefore,  
will require a manual adjustment.  
NOTICE  
screen status.  
Software Version  
1. When the screen is first accessed, start trigger number 1  
is shown. If a different trigger number is desired, the  
installer can rotate the NAVIGATION dial until the desired  
trigger number is displayed. Once the desired trigger  
number is selected, the installer can press the SCROLL  
knob and the day of the week will start to flash.  
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.  
2. The installer can adjust the day of the week to the one he  
wishes to set. Once the day is set, the installer can press the  
NAVIGATION dial and the hour will begin to flash.  
Software version is read only.  
Temperature units (°C / °F)  
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 A3. The default is °F.  
3. After setting the hour, the installer can press the SCROLL  
knob and the minutes will flash. Once all settings have been  
made, the installer can press the RIGHT SELECT [SAVE]  
key. The installer can now select a different trigger and  
adjust the settings for that trigger.  
4. Once all adjustments are made, the installer can press the  
RIGHT SELECT [SAVE] key to save all of the new settings  
and return to the A menu, or press the LEFT SELECT  
[EXIT] key to return to the A menu without saving the  
changes.  
Space Heating (SH) and Domestic Hot Water (DHW)  
Night Setback Offset  
The unit’s internal clock can be set up to run at a lower set  
point temperature during unoccupied times. Both the space  
heating and DHW can be programmed for night setback.  
When in night setback, the control reduces the set point by a  
fixed amount. For space heating, it subtracts the space  
heating night setback offset from each of the SH user set  
points (parameters B1, B6, and B9), or the calculated outdoor  
reset set point (if lower). For DHW, it subtracts the DHW  
night setback offset from the tank set point (parameter E2).  
NOTE: The DHW night setback will not work without a tank  
sensor installed.  
Space Heating (SH) and Domestic Hot Water (DHW)  
Night Setback Off Times  
The corresponding space heating night setback stop triggers are  
set by accessing parameter A6. The stop triggers for the DHW  
night setback feature can be adjusted by accessing parameter A9.  
The adjustment procedure for these parameters is identical to  
the space heating start triggers described above.  
The installer may adjust the space heating night setback offset  
by accessing A4 and the DHW night setback offset by  
accessing parameter A7. The minimum setting is 0°F (0°C)  
and the maximum setting is 90°F (50°C).  
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1 Service  
Display Timeout  
C: Data Logging  
This is the time in which the display remains illuminated.  
The range is 10 seconds to 10 minutes. The default is 3  
minutes.  
Reset last 10 errors  
The reset last 10 errors function clears the last 10 errors log.  
D: Functions  
B: Temperature Settings  
Service Mode Delay  
Space Heating (SH1, SH2, SH3) Set Point  
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 D1. The time range of  
this parameter is 0 to 30 minutes. The default value is 20  
minutes.  
Mixing valves are required for the  
protection of any low temperature loops.  
CAUTION  
There are three (3) individual user set points for better zone  
control. These are listed as SH1 Set Point through SH3 Set  
Point. If multiple set points are calling for heat the highest set  
point has priority. The range is 32°F (0°C) to 190°F (88°C).  
The default is 125°F (52°C).  
Space Heating (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).  
Freeze Protection Pump On  
The SMART SYSTEM control will turn on the boiler and  
system pump outputs whenever the inlet temperature drops  
below this setting. This is done to prevent the water in the  
heat exchanger from freezing. Certain low-temperature  
applications (such as snow melt) can operate at temperatures  
around freezing, so this setting needs to be lowered in these  
cases. The installer can adjust the temperature at which the  
pump outputs are turned on by accessing parameter D2. The  
minimum setting is -4°F (-20°C), and the maximum setting is  
45°F (7.2°C). The default setting is 45°F (7.2°C).  
Space Heating (SH) Maximum Set Point  
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).  
Freeze Protection Burner On  
If running the pumps does not prevent the inlet temperature  
from falling closer to freezing, the SMART SYSTEM control  
will fire the burner at low fire. The installer can adjust the  
temperature at which the burner fires by adjusting parameter  
D3. The minimum setting is -4°F (-20°C), and the maximum  
setting is 45°F (7.2°C). The default setting is 37°F (2.8°C).  
SH1 - SH3 Offset Set Point  
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  
parameters B4, B7 and B10. The temperature range of these  
parameters is 0°F to 20°F. The default value is 10°F.  
Freeze Protection Burner Differential  
Once the burner has started firing due to a low inlet  
temperature, the inlet temperature must increase by this  
amount before the burner turns back off. The installer can  
adjust this differential by accessing parameter D4. The  
minimum setting is 0°F, and the maximum is 20°F. The  
default setting is 5°F (2.8°C).  
SH1 - SH3 Differential Set Point  
The SH differential sets how many degrees below the offset  
the temperature has to drop before the boiler turns back on.  
This parameter can only be changed by the installer by  
accessing parameters B5, B8 and B11. The range is 0°F to  
60°F. The default is 20°F.  
3-Way Valve Time  
Not used.  
20  
Service Manual  
1 Service  
E: DHW Settings  
DHW Boiler Set Point  
(continued)  
DHW/SH Switching Time  
When a boiler has a DHW demand and it receives a space  
heating demand, the SMART SYSTEM control will start a timer.  
Once the timer expires, it will stop the DHW demand and  
service the space heating demand. The installer can adjust the  
length of time the boiler will service the DHW demand by  
accessing parameter E7. The minimum setting is 0 minutes and  
the maximum setting is 200 minutes. The default setting is 30  
minutes.  
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 boiler outlet water temperature.  
This parameter can be changed by the installer by accessing  
parameter E1. The temperature range of this parameter is  
60°F (16°C) to 190°F (88°C). The default value is 180°F  
(82°C).  
Tank Minimum Set Point  
DHW Tank Set Point  
This setting controls the minimum user set point for the tank  
temperature. The installer can adjust this by accessing  
parameter E8. The minimum setting is 60°F (16°C) and the  
maximum setting is the maximum tank set point (parameter  
E9).  
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 below the tank set point differential (parameter E3),  
and finishes the call for heat when the tank temperature  
reaches tank set point. This parameter can be changed by the  
installer by accessing parameter E2. The temperature range of  
this parameter is 68°F (20°C) to 190°F (88°C). The default  
value is 125°F (52°C).  
Tank Maximum Set Point  
This setting controls the maximum user set point for the tank  
temperature. The installer can adjust this by accessing  
parameter E9. The minimum setting is the minimum tank set  
point (parameter E8) and the maximum setting is 185°F (85°C).  
Tank Set Point Differential  
DHW Type  
When a tank sensor is installed, the tank temperature must  
drop this amount below the tank set point (parameter E2)  
before the heater will turn on. The installer can adjust this  
setting by accessing parameter E3. The minimum setting is 0°  
(0°C), and the maximum is 40°F (22°C). The default setting  
is 6°F (3°C).  
This parameter determines whether the Knight XL treats the  
indirect DHW tank as a separate load, or as a zone on the  
primary loop. When programmed as a separate load, the boiler  
will turn on the DHW pump and then turn off the boiler pump  
when an indirect DHW demand begins. When programmed as  
a zone, the boiler will turn on the DHW pump, leave the boiler  
pump on and raise the system set point to the DHW boiler set  
point (parameter E1), if it is higher than the current SH set  
point.  
Boiler Set Point Offset  
This parameter reflects the degrees above DHW boiler set  
point the temperature has to go before the boiler will shut off.  
The range is 0°F (0°C) to 20°F (13°C). The default setting is  
10°F (6°C).  
This setting may be changed by the installer by accessing  
parameter E10. The choices are NORMAL and ZONE. The  
default setting is NORMAL.  
Boiler Set Point Differential  
Fan Speed Limiting for Indirect DHW Tank  
This parameter reflects the degrees below DHW boiler offset  
the temperature has to go before the boiler shuts off. The  
range is 0°F (0°C) to 60°F (33°C). The default setting is 20°F  
(13°C).  
This parameter determines the maximum fan speed (and  
therefore the maximum rate) to be used when heating an  
indirect DHW tank. This setting may be used when the tank is  
unable to accept all of the BTU’s available from the boiler. This  
parameter may be adjusted by the installer by accessing  
parameter E11. The default value is the maximum fan speed for  
that model.  
SH/DHW Switching Time  
When a boiler has a space heating demand and it receives a  
DHW demand, it will immediately switch to the DHW  
demand and start a timer. Once the timer has expired, the  
boiler will switch back to the space heating demand and start  
another timer. Once this timer expires, it will switch back to  
the DHW demand. The installer can adjust the length of time  
the boiler will service the space heating demand by accessing  
parameter E6. The minimum setting is 0 minutes and the  
maximum setting is 200 minutes. The default time is 30  
minutes.  
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SH1 - SH3 Set Point at Low Outdoor Temperature  
F: Outdoor Reset  
When the outdoor air temperature drops below this point, the  
water temperature will be at this 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. These parameters can be  
changed by the installer by accessing parameters F3, F8 and  
F13. The temperature range of this parameter is -40°F (-40°C)  
to 104°F (40°C). The default value is 25°C (-4°C).  
The option of controlling up to three (3) different outdoor  
resets for low outdoor temperatures is available.  
Low Outdoor Temperature  
When the outdoor air temperature drops below this point,  
the water temperature will be at parameters F3, F8 and F13  
(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 -40°F (-40°C) to 104°F (40°C). The default  
SH1 - SH3 Set Point at High Outdoor Temperature  
When the outdoor air temperature rises to or above this point,  
the water temperature will be at this setting (FIG. 1-1). These  
parameters can be changed by the installer by accessing F4, F9  
and F14. The temperature range of this parameter is -40°F (-  
40°C) to 104°F (40°C). The default value is 70°F (21°C).  
value is 25°F  
(-4°C).  
High Outdoor Temperature  
Outdoor Air Shutdown (SH1 - SH3)  
When the outdoor air temperature rises to or above this  
point, the water temperature will be at parameters F4, F9  
and F14 (FIG. 1-1). This parameter can be changed by the  
installer by accessing parameter F2. The temperature range  
of this parameter is -40°F (-40°C) to 104°F (40°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). These parameters can be changed by the installer by  
accessing parameters F5, F10 and F15. The temperature range  
of this parameter is 32°F (0°C) to 104°F (40°C). The default  
value is 70°F (21°C).  
Figure 1-1 Outdoor Air Reset Curve  
22  
Service Manual  
1 Service  
(continued)  
Outdoor Air Shutdown Differential (SH1 - SH3)  
G: Anti-Cycling  
The outdoor air shutdown differential parameter is the  
number of degrees below parameters F5, F10 and F15 the  
outdoor air temperature must go before the boiler will  
respond to a SH demand. These parameters can be  
changed by the installer by accessing parameters F6, F11  
and F16. The temperature range of this parameter is 0°F  
(0°C) to 90°F (50°C). The default value is 10°F (6°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 10 minutes. The default  
value is 1 minute.  
Shift Reset Curve (SH1 - SH3)  
There is a shift reset curve for each outdoor reset. The shift  
reset curve parameter shifts the actual set point above the  
calculated set point the number of degrees in this  
parameter. These parameters can be changed by the  
installer by accessing parameter F7, F12 and F17. The  
temperature range of this parameter is -17°F (-27°C) to  
18°F (-8°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 Override Differential  
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  
(6°C).  
Boost Temperature  
If a SH demand lasts longer than the programmed time  
delay setting (F19) 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 F18. The temperature  
range of this parameter is 0°F (0°C) to 25°F (-4°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).  
Ramp Delay (Enable / Disable)  
This parameter allows the installer to enable or disable the SH  
ramp delay by accessing parameter G4.  
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 F19.  
The time range for this parameter is 0 minute to 50  
minutes. The default value is 0 minutes.  
23  
Service Manual  
1 Service  
SH Ramp Delay  
H: Control modes  
Please note that the brackets ([])  
denote screen status.  
Controlling Sensor  
NOTICE  
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.  
The SMART SYSTEM control can be programmed to limit  
the firing rate for a fixed period of time at the start of a  
space heating demand. There are six (6) possible limits,  
each with their own time delay. The first limit applies as  
soon as the burner starts. Once its time delay expires, the  
second limit is applied and its timer begins. The control  
steps through these limits until the 6th (sixth) limit expires.  
Note, however, that the rate can be held to less than 100% if  
so desired. The installer can adjust the firing limits and  
time delays by accessing parameter G4. Once this  
parameter is selected, the screen will show the step number,  
the time delay for that step and the limit value  
corresponding with that step. If the installer wishes to  
adjust one of the values in that step, he can press the  
NAVIGATION dial until the value he wishes to change is  
flashing. The installer can then rotate the NAVIGATION  
dial to adjust that value. If the installer presses the RIGHT  
SELECT [SAVE] key while the limit value is flashing, the  
step value will flash again. The installer can then select the  
next step and adjust the delay and limit values  
corresponding with that step.  
BMS Thermostat Input (Active / Inactive)  
When controlling the boiler through the 0 - 10V BMS input or  
through ModBus, the boiler can be enabled one of two ways.  
With parameter H2 set to ACTIVE, the boiler will enabled by  
closing the Room Thermostat 1 input. With parameter H2 set  
to INACTIVE, the boiler will be enabled by the voltage level on  
the 0 - 10V input (in the case of 0 - 10V BMS control), or the  
0 - 10V input value received through ModBus. The default  
value is INACTIVE.  
BMS (Active / Inactive)  
The set point or modulation of the boiler may be controlled  
through the 0 - 10V BMS input or through Modbus. When  
parameter H3 is set to INACTIVE, the 0 - 10V input will be  
ignored. When set to ACTIVE, the set point or modulation will  
be controlled by the voltage on the 0 - 10V input (in the case of  
0 - 10V BMS control), or the 0 - 10V input value received  
through ModBus. The default value is INACTIVE.  
When finished, the installer can press the RIGHT SELECT  
[SAVE] key to store the new settings, or the LEFT SELECT  
[EXIT] key to return to the G parameter list without saving  
the changes. The delay value can be set between 0 minutes  
and 120 minutes. The limit value can be set between 0%  
and 100%.  
Figure 1-2 Ramp Delay Interval  
24  
Service Manual  
1 Service  
(continued)  
As the calculated load increases further and both boilers ramp  
up to 90%, it lowers the rate of the first two (2) boilers to 60%  
and brings the next boiler on at 60%. The three (3) boilers  
then modulate together. As the calculated load decreases, the  
boilers will reach a lower threshold (default = 35%), at which  
time the last boiler (the third in our example) will turn off and  
the Cascade will increase the rates of the remaining boilers to  
provide the equivalent total output as before ((3 x 35%) / 2 =  
52.5% in our example).  
Modbus (Active / Inactive)  
When BMS is set to ACTIVE (see BMS Active / Inactive)  
and the boiler is being controlled through Modbus, set  
parameter H4 to ACTIVE. Otherwise, set the Modbus  
parameter to INACTIVE. Note that the boiler can still be  
monitored by ModBus with this parameter set to  
INACTIVE. The default value is INACTIVE.  
Modbus T/O (Timeout)  
The amount of time the unit controls will wait to receive a  
communication string from the BMS controller before  
reverting back to its own internal parameters. This  
parameter is adjustable by the installer by accessing  
parameter H5. The default value is 10 seconds.  
Maximum Cascade Outlet 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 maximum cascade set point, the boiler  
will then modulate down on its own in order to keep its outlet  
temperature within the maximum 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 H8. The default maximum cascade set  
point is 185°F (85°C).  
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 H6. The outdoor air (if used) and  
system supply sensor must be connected to the Leader  
boiler. The default address is 1.  
If installing the boilers in an existing system, the new boilers  
should be programmed as the Leader and/or the higher  
number addresses.  
Cascade Offset  
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 H9. The default value is 10°F (6°C).  
Cascade Type (L/L / EFF)  
There are two (2) options for the way a Cascade divides the  
load between its heaters. The first is Lead/Lag, designated  
at L/L in the menu. This method is used when it is desired  
to have the least amount of total flow through the boilers.  
This method works much like the current Cascade, except  
it will modulate the last two (2) boilers, instead of just the  
last boiler. This change provides for smoother transitions  
when a boiler turns on or off. When the last boiler reaches  
100% and the calculated load is still increasing, it will start  
the next boiler at 20% and reduce the previous boiler to  
80%, thus eliminating the sudden jump in total output of  
the Cascade. Therefore, the dead-zone we had in the  
original Cascade is no longer necessary. When the  
calculated load is decreasing and the last boiler gets down  
to 20% fire, it will hold it there and start lowering the firing  
rate on the next-to-last boiler. When the next-to-last boiler  
reaches 35%, it will turn the last boiler off and raise the rate  
of the next-to-last boiler to 55%, thus eliminating the  
sudden drop in total output of the Cascade.  
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 H10. The default value is 20°F  
(11°C).  
Minimum On/Off Time  
In order to prevent units in a Cascade from short cycling, this  
parameter defines the minimum ON and OFF time for each  
unit. The installer can adjust this time by accessing parameter  
H11. The minimum setting is 0 seconds and the maximum  
setting is 10 minutes. The default is 30 seconds.  
Minimum Next On Time  
In order to reduce the risk of temperature overshoot with a  
Cascade, this parameter defines the minimum time delay from  
starting one unit until the next unit may be started. The  
installer can adjust this time delay by accessing parameter H12.  
The minimum setting is 0 minutes and the maximum setting is  
10 minutes. The default is 60 seconds.  
The other Cascade divider method is Efficiency  
Optimization, designated as EFF in the menu. This method  
is used, as the name implies, when it is desired to have the  
most efficient system. When the first boiler reaches a  
certain rate (default = 90%), it lowers its rate to 45% and  
turns on the next boiler at 45%. The two (2) boilers then  
modulate at the same rate.  
Boiler Size  
Not used.  
25  
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1 Service  
DHW Pump Anti-Seize Delay  
I: Circulation pumps  
If the boiler pump does not run for 24 hours, it will be turned  
on briefly to prevent it from seizing. The length of time it runs  
is determined by parameter I4. The range of this setting is 0  
seconds to 40 minutes. The default setting is 20 seconds.  
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.  
System Pump Anti-Seize Delay  
If the boiler pump does not run for 24 hours, it will be turned  
on briefly to prevent it from seizing. The length of time it runs  
is determined by parameter I4. The range of this setting is 0  
seconds to 40 minutes. The default setting is 20 seconds.  
Boiler 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.  
J: BMS  
BMS Type (Power / Set Point)  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus, the 0 - 10V signal can be interpreted  
as either a modulation command or a set point. When  
parameter J1 is set to POWER, the 0 - 10V signal will control  
the modulation. When set to SETPOINT, the 0 - 10V signal will  
control the SH set point. The default setting is POWER.  
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 Volts at Minimum  
accessing parameter I3. The time range for this parameter is  
0 minutes to 40 minutes. The default time is 30 seconds.  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus, parameter J2 should be set to the  
minimum voltage signal sent to the SMART SYSTEM control.  
The range of this parameter is 0.0V to the Volts at Minimum  
value (parameter J3). The default setting is 2.0V.  
Boiler Pump Anti-Seize Delay  
If the boiler pump does not run for 24 hours, it will be turned  
on briefly to prevent it from seizing. The length of time it  
runs is determined by parameter I4. The range of this setting Volts at Maximum  
is 0 seconds to 40 minutes. The default setting is 20 seconds.  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus, parameter J3 should be set to the  
maximum voltage signal sent to the SMART SYSTEM control.  
The range of this parameter is the Minimum value (parameter  
J2) to 10.0V. The default value is 10.0V.  
Boiler Pump Minimum Voltage  
The speed of the boiler pump can be controlled by the  
SMART SYSTEM control in order to maintain a minimum  
ΔT through the heat exchanger. Thus, as the firing rate  
decreases, the speed of the boiler pump can decrease as well. Rate at Minimum Volts  
The SMART SYSTEM control outputs a 0 - 10V signal to the  
When programmed for BMS control through the 0 - 10V BMS  
boiler pump to control its speed. Parameter I5 determines the  
minimum voltage given to the boiler pump, thereby setting its  
minimum speed. The range of this setting is 2.5V to 10V. The  
default setting is 3.5V.  
input or through ModBus and the BMS Type is programmed as  
POWER, the modulation percentage represented by the Volts at  
Minimum parameter (J2) is set by parameter J4. The  
minimum value is 0% and the maximum is the Power at  
Maximum Volts setting J5. The default value is 20%.  
System Pump Type (CFH / WWSD) CFH = Call for  
Heat, WWSD = Warm Weather Shutdown  
Rate at Maximum Volts  
The system pump can be programmed to operate in response  
to any of the Room Thermostat inputs, or to run continuously  
until the boiler goes into Outdoor Shutdown. To program the  
system pump to operate only with a space heating call for  
heat, set parameter I6 to CFH. To program the system pump  
to run continuously until outdoor shutdown starts, set  
parameter I6 to WWSD. The default setting is CFH.  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus and the BMS Type is programmed as  
POWER, the modulation percentage represented by the Volts at  
Maximum parameter (J3) is set by parameter J5. The  
minimum value is the Power at Minimum Volts setting J4 and  
the maximum is 100%. The default value is 100%.  
26  
Service Manual  
1 Service  
(continued)  
Set Point at Minimum Volts  
Service Notification Cycles  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus and the BMS Type is programmed as  
SETPOINT, the set point represented by the Volts at Minimum  
parameter (J2) is set by parameter J6. The minimum value is  
32°F (0°C) and the maximum is the Set Point at Maximum Volts  
setting J7. The default value is 70°F (21°C).  
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 K3. The range for this parameter is 0 cycles to  
100,000 cycles. The default is 50,000 cycles.  
Set Point at Maximum Volts  
Reset Maintenance Reminder  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus and the BMS Type is programmed as  
SETPOINT, the set point represented by the Volts at Maximum  
parameter (J4) is set by parameter J7. The minimum value is the  
Set Point at Minimum Volts setting J6 and the maximum is  
190°F (88°C). The default value is 180°F (82°C).  
Once servicing has been completed, the service notification  
counter should be reset. This parameter can be reset by the  
installer by accessing parameter K4. Once accessed, press  
the RESET key to reset the service notification counter.  
Installer Name and Phone Number  
On Volts  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus and the BMS Thermostat Input is set  
to INACTIVE, parameter J8 determines the 0 - 10V BMS input  
voltage at which the boiler is enabled. The minimum value is  
0.5V and the maximum is 10.0V. The default value is 2.0V.  
Please note that the brackets ([]) denote  
screen status.  
NOTICE  
When a Maintenance Reminder timer or counter has  
expired, a Maintenance Reminder screen will appear on the  
display. By programming the installer’s name and phone  
number, this information will appear on the Maintenance  
Reminder Screen at that time. This can be programmed by  
accessing parameter K5. When selected, another menu will  
appear with PHONE and NAME.  
Off Differential Volts  
When programmed for BMS control through the 0 - 10V BMS  
input or through ModBus and the BMS Thermostat Input is set  
to INACTIVE, parameter J9 determines how far below the On  
Volts setting J8 the 0 - 10V BMS input voltage must be in order  
to disable the boiler. The minimum value is 0.2V and the  
maximum is the On Volts setting J8. The default value is 1.0V.  
1. Rotate the NAVIGATION dial to point to the  
name/phone number to program and press the  
NAVIGATION dial. The screen will now display the  
selected item (either PHONE or NAME).  
K: Service Notification  
2. Press the NAVIGATION dial again. A cursor will  
appear at the bottom of the screen. By rotating the  
NAVIGATION dial, various numbers and characters  
will appear. When the desired number/character is  
found, press the NAVIGATION dial. The cursor will  
move to the next position.  
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 K1. The time range for this parameter is 0  
months to 36 months. The default time is 0 months.  
3. Repeat this procedure until the entire message is  
entered. If you make a mistake and wish to back up  
one character, select the back arrow (←) character and  
press the NAVIGATION dial.  
This feature has been disabled by the manufacturer. To enable  
this feature change parameter K1 to the desired time range.  
4. When finished, press the RIGHT SELECT [SAVE] key  
to return to the previous menu.  
Service Notification Running Time  
When the boiler control determines that a scheduled service is  
due based on the hours of actual operation, the boiler display  
will turn yellow and a new status screen will appear informing  
the installer that maintenance is required. This parameter is  
adjustable by the installer by accessing parameter K2. The time  
range for this parameter is 0 hours to 100,000 hours. The default  
time is 8,760 hours.  
27  
Service Manual  
2 Maintenance  
Maintenance and annual startup  
Table 2-1 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 condensate drain system  
• Check air vents  
• Check wiring and connections  
• 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  
28  
Service Manual  
2 Maintenance  
(continued)  
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 2-1 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.  
29  
Service Manual  
2 Maintenance  
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.  
30  
Service Manual  
2 Maintenance  
(continued)  
Inspect ignition and flame sense  
electrodes  
Figure 2-2 Burner Assembly - Model 400  
1. Remove the ignition and flame sense electrodes from the  
boiler heat exchanger access cover.  
2. Remove any deposits accumulated on the ignition/flame  
sense electrode using sandpaper. If the electrodes cannot  
be cleaned satisfactorily, replace with new ones.  
AIR / GAS ARM  
3. Replace ignition/flame sense electrode, making sure  
gasket is in good condition and correctly positioned.  
Check ignition ground wiring  
1. Inspect boiler ground wire from the heat exchanger access  
cover to ground terminal strip.  
BURNER  
GASKET  
2. Verify all wiring is in good condition and securely  
attached.  
SCREWS  
(QTY. 5)  
3. Check ground continuity of wiring using continuity  
meter.  
Figure 2-3 Burner Assembly - Model 501  
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.  
AIR / GAS ARM  
Check control settings  
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.  
2. Check settings of external limit controls (if any) and  
adjust if necessary.  
BURNER  
GASKET  
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.  
SCREWS  
(QTY. 5)  
Figure 2-4 Burner Assembly - Models 601 - 801  
2. Verify cold fill pressure is correct and that operating  
pressure does not go too high.  
Check burner flame  
1. Inspect flame through observation window.  
AIR ARM  
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.  
BURNER  
GASKET  
3. Remove the burner, reference FIG.’s 2-2 thru 2-4.  
SCREWS  
(QTY. 5)  
4. When replacing the burner, ensure gasket is in good  
condition and positioned correctly (FIG.’s 2-2 thru 2-4).  
31  
Service Manual  
2 Maintenance  
5. Remove the condensate hose from the heat exchanger end.  
Connect a field supplied 3/4" diameter hose to a drain pan.  
Using field supplied means, cover the refractory in the back  
of the combustion chamber of the heat exchanger.  
Check flame signal  
1. At high fire the flame signal shown on the display should  
be at least 10 microamps.  
6. Use a vacuum cleaner to remove any accumulation on the  
boiler heating surfaces. Do not use any solvent.  
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.  
7. Brush the heat exchanger while dry using a nylon bristle  
brush. Caution: DO NOT use a metal brush. Re-vacuum  
the heat exchanger.  
8. Finish cleaning using a clean cloth dampened with warm  
water. Rinse out debris with a low pressure water supply.  
3. See Section 3 - Troubleshooting in this manual for other  
procedures to deal with low flame signal.  
9. Allow the heat exchanger to thoroughly dry.  
10. Remove the field supplied rear refractory cover from the  
back of the combustion chamber of the heat exchanger and  
reassemble.  
Review with owner  
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.  
1. Review the Knight XL User’s Information Manual with  
the owner.  
2. Emphasize the need to perform the maintenance  
schedule specified in the Knight XL User’s Information  
Manual (and in this manual as well).  
12. Perform start-up and check-out procedures in the Check  
Flame and Combustion - Section 10 - Startup of the  
Installation and Operation Manual.  
3. Remind the owner of the need to call a licensed  
contractor should the boiler or system exhibit any  
unusual behavior.  
13. Replace the access cover and restore boiler to operation.  
Table 2-2 Heat Exchanger Cleaning Kits  
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.  
Kit  
Part  
Component  
Description  
Model  
Number Number  
CTN20005  
Rear Refractory Cover  
MSC20083*  
Nylon 4" Wheel Brush*  
Cleaning boiler heat exchanger  
400  
KIT30063  
For recommended materials; including brush, appropriate  
extension(s), refractory cover, and detailed instructions see  
Table 2-2 - Heat Exchanger Cleaning Kits.  
MSC20084  
3mm Allen Wrench  
1/4" x 24" Drill Extension  
Rear Refractory Cover  
Nylon 4" Wheel Brush*  
1/4" x 12" Drill Extension  
1/4" x 24" Drill Extension  
MSC20086  
CTN20005  
1. Shut down boiler:  
501  
-
801  
MSC20083*  
KIT30064  
• Follow the “To Turn Off Gas to Appliance” instructions  
for the boiler in Section 10 - Startup of the Installation  
and Operation Manual.  
MSC20085  
MSC20086  
• Do not drain the boiler unless it will be exposed to  
freezing temperatures. If using freeze prevention fluid  
in system, do not drain.  
* Do NOT use a metal brush. Only use the  
kit provided brush or an equivalent  
replacement nylon brush.  
ƽ CAUTION  
2. Allow time for the boiler to cool to room temperature if  
it has been firing.  
3. Remove the nuts securing the heat exchanger access cover  
to the heat exchanger and set aside.  
4. Remove the heat exchanger access cover, burner, and  
gas/air arm assembly.  
The boiler contains ceramic fiber  
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.  
32  
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.  
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  
Always  
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 F1, F2, and F3, 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.  
b. Continuity checker.  
c. Contact thermometer.  
F3 - .80 AMP FUSE  
24V DC POWER SUPPLY  
2. Check for 120 VAC (minimum 102 VAC to maximum  
132 VAC) to boiler.  
F1 - 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  
BLOWER  
5. The boiler is shipped with three (3) spare fuses in a plastic bag  
attached to the control module cover.  
4. Make sure all external limit controls are installed and  
operating.  
6. If necessary, replace open fuse (F3 is .80 amps, F2 is 3.15 amps  
and F1 is 5 amps).  
Check the following:  
Note: Fuses F1, F2, and F3 are all slow blow fuses.  
1. Wire connectors to control module are securely  
plugged in at the module and originating control.  
Do not jumper fuse or replace with any fuse  
ƽ WARNING  
except as specified. Failure to comply could  
2. Gas pressures:  
result in severe personal injury, death, or  
substantial property damage.  
• Maximum: 14 inches w.c. (3.5 kPa) (natural and  
LP) with no flow (lockup) or with boiler on  
• Minimum: 4 inches w.c. (1.0 kPa) (natural),  
8 inches w.c. (2.0 kPa) (LP) with gas flowing (verify  
during boiler startup)  
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 XL  
Installation and Operation Manual) after completing boiler  
service.  
33  
Service Manual  
3 Troubleshooting  
Table 3-1 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 33 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  
3-2B on page 35 of this manual.  
- Unit locked out on fault.  
- Ramp delay active.  
• Consult display for specific fault. Refer to fault  
descriptions on page 37 of this manual for corrective  
actions.  
• Check ramp delay parameter settings. Optional PC  
software required.  
• Turn ramp delay feature off. See page 23 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 3-2D on page 35 of this manual.  
34  
Service Manual  
3 Troubleshooting  
(continued)  
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  
It is important to note that the flue and outlet water sensors have two temperature sensing devices in one housing. These devices  
are designated as S1a/S1b, outlet sensor and S3a/S3b, flue sensor. Please reference the wiring diagram in the Knight XL  
Installation and Operation Manual for correct terminal location.  
Table 3-2A - Inlet Water/System Sensor Resistance vs.  
Temperature  
Table 3-2B - Outdoor Air Sensor Resistance vs.  
Temperature  
Temperature Resistance Temperature Resistance  
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  
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  
0
10  
62,465  
Table 3-2C - Outlet Water Sensor Resistance vs. Temperature  
S1a  
S1b  
(Wire Color - R/BK and Y)  
(Wire Color - G and Y)  
Temperature Resistance Temperature Resistance Temperature Resistance Temperature Resistance  
50  
68  
19,553  
12,690  
8,406  
5,715  
3,958  
2,786  
158  
176  
194  
212  
2,004  
1,464  
1,084  
816  
50  
68  
40,030  
25,030  
16,090  
10,610  
7,166  
158  
176  
194  
212  
3,478  
2,492  
1,816  
1,344  
86  
86  
104  
122  
140  
104  
122  
140  
4,943  
Table 3-2D - Flue Sensor Resistance vs. Temperature  
S3a  
S3b  
(Wire Color - W/B and Y)  
(Wire Color - PR and Y)  
Temperature Resistance Temperature Resistance Temperature Resistance Temperature Resistance  
50  
68  
40,030  
25,030  
16,090  
10,610  
7,166  
158  
176  
194  
212  
3,478  
2,492  
1,816  
1,344  
50  
68  
258,500  
125,500  
80,220  
52,590  
35,270  
24,160  
158  
176  
194  
212  
16,870  
12,000  
8,674  
86  
86  
104  
122  
140  
104  
122  
140  
6,369  
4,943  
35  
Service Manual  
3 Troubleshooting  
Table 3-3 Troubleshooting Chart - Noisy System  
FAULT  
CAUSE  
CORRECTIVE ACTION  
-
Supply gas problem.  
Natural gas • Refer to Section 7 - Gas Connections of the Knight  
pressures should be between 4 inches XL Installation and Operation Manual for detailed  
w.c. and 14 inches w.c. LP gas pressures information concerning the gas supply.  
should be between 8 inches w.c. and 14  
inches w.c.  
- Gas/air mixture problem.  
- Dirty/damaged burner.  
• Refer to the Gas Valve Adjustment Procedure on  
page 45 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.  
• Refer to page 31 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.  
• Verify system pressure is a minimum of 12 psi.  
- Low system water pressure.  
- Blown fuse.  
• Replace fuse F1 on the control board, see page 33 of  
this manual.  
No Pump  
Operation -  
Boiler Pump  
System Pump  
or  
Note: Make sure pump amperage does not exceed  
1.8 amps.  
DHW Pump  
• Replace pump.  
- Faulty pump.  
- Internal fault on control board.  
• Replace main control board.  
-System pressure exceeds relief valve • Lower the system pressure below the 30 psi rating of  
setting.  
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.  
36  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3-4 Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
• Reset the pressure switches.  
• Measure the supply gas pressure to determine cause  
of failure. Natural gas pressures should be between  
Gas Pressure SW  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
4
-
14 inches w.c. and LP gas pressures  
should be between 8 - 14 inches w.c.  
Either the optional manual reset low gas  
pressure switch or the optional manual reset • Refer to Section 7 - Gas Connections of the Knight  
high gas pressure switch tripped.  
XL Installation and Operation Manual for detailed  
information concerning the gas supply.  
• Correct the supply gas pressure if necessary.  
• Check for a loose or misplaced jumper if pressure  
switches are not installed.  
• Check boiler pump operation on a call for heat.  
• Check for closed valves or obstructions in the boiler  
piping.  
Flow  
Switch/LWCO  
Either the optional flow switch or the optional  
• Verify system is full of water and all air has been  
purged from the system.  
(will require a manual low water cutoff is not making.  
reset once condition has  
been corrected. Press the  
RESET button on the  
SMART SYSTEM display  
• Check for loose or misplaced jumpers if flow switch or  
LWCO is not installed.  
• Replace fuse F3 on the control board, see page 33  
of this manual.  
to reset.)  
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.  
• Check the wiring connections to switch. Wires should  
be connected to the common and normally closed  
terminals.  
• 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.  
APS  
Open  
• Check for obstruction or blockage in the air  
intake pipes or at terminations.  
(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 reference hoses connected to the air pressure  
switch for blockage or obstruction.  
• Inspect the burner. Reference page 31 of this manual  
for removal and cleaning procedures. Replace if  
necessary.  
• Inspect the heat exchanger. Reference page 32 of  
this manual for removal and cleaning procedures.  
Replace if necessary.  
• Faulty air pressure switch. Replace switch.  
37  
Service Manual  
3 Troubleshooting  
Table 3-4 (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.  
damage and connection. Reference page 31 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. and  
LP gas pressures should be between 8 - 14 inches w.c.  
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.  
Flame Fail Ign  
(will require a manual  
reset once the condition  
has been corrected.  
Press the RESET button  
on the SMART SYSTEM  
display to reset.)  
• 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 or Gas Valve Fail fault.  
• 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 31 of this manual for removal and  
cleaning procedures. Replace if necessary.  
• Inspect the burner. Reference page 31 of this manual  
for removal and cleaning procedures. Replace if  
necessary.  
• Replace the main control board.  
38  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
Flame  
Sequence  
• 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.  
(will require a manual  
reset once the condition  
has been corrected.  
Press the RESET button  
on the SMART  
The flame detector circuit is seeing a flame  
signal while no flame is present.  
SYSTEM display to  
reset.)  
• 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 120 vac to boiler pump motor on a call for  
heat. If voltage is not present, check wiring back to  
the main control board.  
• Replace the main control board if necessary.  
• If 120 vac is present on a call for heat and the boiler  
pump is not operating, replace the pump.  
The outlet water temperature has exceeded  
the setting of the automatic reset high limit.  
Auto Reset  
High Limit  
• If the system pump is a variable speed pump, ensure  
that the system flow is not less than the boiler flow.  
• If operating on something other than an outlet sensor,  
check temperature setting of the main control board.  
• If the optional manual reset high limit has tripped,  
check setting of the device.  
• Check resistance of water sensors and compare to  
Table 3-2A on page 35 of this manual. Replace  
sensor if necessary.  
• Replace high limit.  
The actual fan RPM is 30% lower than what • Vent/air intake lengths exceed the maximum allowed  
is being called for.  
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  
• 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.  
SYSTEM display to  
reset.)  
• Replace the main control board.  
• Replace fuse F2 on the control board, see page 33  
of this manual.  
Blown fuse.  
39  
Service Manual  
3 Troubleshooting  
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
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. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
The main control board did not detect the  
gas valve.  
• Replace the gas valve wire harness.  
• Replace the gas valve.  
• Replace the main control board.  
• 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.)  
Either the inlet water or outlet water • Measure the resistance of the sensors and compare  
temperature sensor has been disconnected.  
the resistance to the tables on page 35 of this  
manual.  
• 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 35 of this  
manual.  
• Replace the sensor if necessary.  
Louver Proving  
Sw  
(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.  
40  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
• Inspect the heat exchanger. Reference page 32 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 3-2D on page 35 of this manual.  
Replace the sensor if necessary.  
The stack temperature has exceeded the set  
parameters for the boiler.  
Flue Temp High  
• Verify that the vent/air intake pipes are properly  
installed and that there are no obstructions.  
• Replace the main control board.  
• 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 120 vac to the boiler pump motor on a call  
for heat. If voltage is not present, check the wiring  
back to the main control board. Replace the main  
control board if necessary.  
Delta T High  
The temperature rise across the heat  
exchanger has exceeded the set parameters  
for the boiler.  
• 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  
XL Installation and Operation Manual for boiler  
pump specifications.  
• 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.  
Outlet Temp  
High  
Outlet water temperature has exceeded the  
maximum outlet water temperature.  
• Check for 120 vac to the boiler pump motor on a call  
for heat. If voltage is not present, check wiring back  
to the main control board. Replace the main control  
board if necessary.  
• If 120 vac is present on a call for heat and the boiler  
pump is not operating, replace the pump.  
41  
Service Manual  
3 Troubleshooting  
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
• 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.  
Outlet Temp  
High  
(continued)  
Outlet water temperature has exceeded the  
maximum outlet water temperature.  
• Replace the main control board.  
• Check set point of the external control.  
• Check the wiring between the external control and the  
unit.  
External control is cycling too often.  
Rem Ctrl Flt  
• Replace the control.  
Parameters  
Progr  
(will require a manual  
reset once the condition  
has been corrected. Press  
the RESET button on the  
SMART SYSTEM display  
to reset.)  
• Press the ENTER/RESET button on the SMART  
SYSTEM display panel.  
After downloading parameters from a laptop,  
the main control board must be reset.  
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 120 vac to the boiler pump motor on a call for  
heat. If voltage is not present, check the wiring back  
to the main control board. Replace the main control  
board 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.  
42  
Service Manual  
3 Troubleshooting  
(continued)  
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface  
FAULT  
DESCRIPTION  
CORRECTIVE ACTION  
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.  
• Replace the main control board.  
Watch Dog Error  
Write EEProm  
The main control board has detected an  
internal fault.  
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 • Replace the main control board.  
internal fault.  
43  
Service Manual  
3 Troubleshooting  
Combustion Analysis Procedure  
Table 3-6 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  
RIGHT SELECT [ON] key (see page 7).  
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 below the RESET button on  
the display board (see page 7). Insert a thin wire (such as  
a paper clip) into the hole and 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 3-6 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 3-5 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 31 of this manual for burner removal and cleaning procedures.  
• Replace burner if necessary.  
• Refer to page 45 of this manual for the gas valve adjustment procedure.  
Gas Valve Adjustment  
44  
Service Manual  
3 Troubleshooting  
(continued)  
Gas valve adjustment procedure  
Figure 3-3 Gas Valve Adjustment: Model 501  
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 400  
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 44 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 3-5 on  
page 44 or replace the gas valve.  
Models 601 - 801  
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 400  
the valve, follow the Combustion Analysis Procedure on page  
44 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 3-5 on page 44 or replace the gas  
valve.  
Figure 3-4 Gas Valve Adjustment: Models 601 - 801  
Model 501  
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 44 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 3-5 on  
page 44 or replace the gas valve.  
45  
NOTES  
46  
NOTES  
47  
Revision Notes: Revision A (ECO #C05747) initial release. Reflects  
the new model numbers for the Knight XL upgrade.  
Revision B (ECO #C06234) reflects changes made to the Service  
Notification parameter.  
.
KBXII-SER Rev B  
8/10  

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