Lochinvar Power-Fin Designer's Manual page 43

Designer's Guide Power-fin Water Heater
18. Low voltage connection board
The low voltage connection board provides a location to tie in all of the low voltage contacts to the appliance. This is
where most of the external safety devices are connected to the unit such as the tank thermostat or tank sensor.
19. Condensate trap
The condensate trap is designed to prevent flue gases from escaping the appliance through the combustion chamber
drain.
20. Access cover - front
The front access cover provides access to the gas train as well as the blower and other key components for service
and maintenance.
21. Hot surface igniter (HSI)
The hot surface igniter is a device that is used to ignite the air/gas mixture as well as monitor the performance of the
flame during operation. This device also acts as a flame sense electrode.
22. Flame inspection window (sight glass)
The flame inspection window is a quartz glass window that allows a visual inspection of the burner and flame during
operation.
23. Gas shut off valve (downstream test cock)
The downstream test cock is provided in the gas train to ensure complete shut off of the gas to the burner in case of
maintenance, inspection, or testing of the valve.
24. High limit sensor
A device that monitors the outlet water temperature to ensure safe operation. If the temperature exceeds its setting
(field adjustable), it will break the control circuit, shutting the appliance down.
25. Relief valve
The relief valve is a safety device that ensures the maximum pressure of the appliance is not exceeded. Water
heaters receive 150 PSI Temperature & Pressure relief valves.
26. Power switch
The power switch is used to engage and disengage power to the appliance on the 120 VAC circuit.
27. Air pressure switch
The air pressure switch is a safety device which ensures proper blower operation. The air pressure switch is wired in
series with the low voltage control circuit in such a way that if the fan does not engage or shuts down prematurely the
device will break the control circuit and the unit will shut down.
28. Flow switch
The flow switch is a safety device that ensures flow through the heat exchanger during operation. This appliance is
low mass and should never be operated without flow. The flow switch makes contact when flow is detected and
allows the unit to operate. If flow is discontinued during operation for any reason the flow switch will break the control
circuit and the unit will shut down.
29. Drain port(s)
Location from which the heat exchanger can be drained.
30. Ventilation fan
Provides air circulation around the controls inside the unit.
31. Manual shutoff valve
Manual valve used to isolate the unit from the gas supply.
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LOCHINVAR CORPORATION
300 MADDOX SIMPSON PKWY
LEBANON, TN 37090
www.lochinvar.com