The knight wall mount boiler - how it works – Lochinvar KNIGHT 51 User Manual
Page 4

Installation & Operation Manual
4
The Knight Wall Mount Boiler - How it works...
1.
Stainless steel heat exchanger
Allows system water to flow through specially designed 
coils for maximum heat transfer, while providing 
protection against flue gas corrosion. The coils are 
encased in a jacket that contains the combustion process.
2.
Combustion chamber access cover
Allows access to the combustion side of the heat 
exchanger coils.
3.
Blower
The blower pulls in air and gas through the venturi (item 
5). Air and gas mix inside the blower and are pushed into the 
burner, where they burn inside the combustion chamber. 
4.
Gas valve
The gas valve senses the negative pressure created by the 
blower, allowing gas to flow only if the gas valve is 
powered and combustion air is flowing. 
5.
Venturi
The venturi controls air and gas flow into the burner.
6.
Flue gas sensor (limit rated)
This sensor monitors the flue gas exit temperature. The control 
module will modulate and shut down the boiler if flue gas 
temperature gets too hot. This protects the flue pipe from 
overheating.
7.
Boiler outlet temperature sensor (housed with high 
limit sensor)
This sensor monitors boiler outlet water temperature (system 
supply). If selected as the controlling sensor, the control 
module adjusts boiler firing rate so the outlet temperature is 
correct.
8.
Boiler inlet temperature sensor
This sensor monitors return water temperature (system 
return). If selected as the controlling sensor, the control 
module adjusts the boiler firing rate so the inlet temperature is 
correct.
9.
Temperature and pressure gauge (field installed, not 
shown)
Monitors the outlet temperature of the boiler as well as the 
system water pressure.
10. Electronic LCD display
The electronic display consists of 4 buttons, a navigation dial 
and a multiple line liquid crystal display. 
11. Flue pipe adapter
Allows for the connection of the PVC vent pipe system to the 
boiler.
12. Burner (not shown)
Made with metal fiber and stainless steel construction, 
the burner uses pre-mixed air and gas and provides a 
wide range of firing rates.
13. Water outlet (system supply)
The water outlet is the water connection for water leaving the 
boiler and entering the system. Boiler connection is 1".
14. Water inlet (system return)
The water inlet is the water connection for water entering the 
boiler from the system. Boiler connection is 1".
15. Gas connection pipe
Threaded pipe connection of 1/2". This pipe should be 
connected to the incoming gas supply for the purpose of 
delivering gas to the boiler.
16. SMART SYSTEM Control Module
The SMART SYSTEM Control responds to internal and 
external signals and controls the blower, gas valve, and pumps 
to meet the heating demand. 
17. Air intake adapter
Allows for the connection of the PVC air intake pipe to 
the boiler.
18. High voltage junction box
The junction box contains the connection points for the line 
voltage power and all pumps.
19. Manual air vent
Designed to remove trapped air from the heat exchanger 
coils.
20. Low voltage connection board
The connection board is used to connect external low voltage 
devices.
21. Low voltage wiring connections (knockouts)
Conduit connection points for the low voltage 
connection board.
22. Condensate drain connection
Connects the condensate drain line to a 1/2" pipe.
23. Access door
Provides access to all internal components.
24. Ignition electrode
Provides direct spark for igniting the burner.
25. Flame inspection window
The quartz glass window provides a view of the burner 
surface and flame.
26. Gas shutoff switch
An electrical switch designed to cut power to the gas valve to 
prevent releasing any gas.
27. High limit sensor (housed with outlet sensor)
Device that monitors the outlet water temperature. If the 
temperature exceeds its setting, it will break the control circuit, 
shutting the boiler down.
28. Relief valve
Protects the heat exchanger from an over pressure condition. 
The relief valve provided with the unit is set at 30 psi.
29. Flame sensor
Used by the control module to detect the presence of burner 
flame.
30. Line voltage wiring connections (knockouts)
Conduit connection points for the high voltage junction box.
31. Air pressure switch
The air pressure switch detects blocked inlet conditions.
32. Transformer
The transformer provides 24V power to the integrated control.
