The hopper lid switch is a basic interrupter switch, which is normally open and closes the circuit when the switch plunger is depressed. The wires for the switch are black and red and are wrapped in a gray rubber sheathing. The cord travels down the inside of the hopper towards the control board, exits the hopper and is connected to a white wire leading to the controller on one side and another white wire which is attached to the pressure switch. This circuit is the common return for both the feed motor and the igniter.
If your stove is not feeding or igniting at start up, try disconnecting the hopper lid switch from the circuit by plugging the two white wires together that are attached to each of the hopper lid switch wires. If your stove or insert resumes normal operation, replace the lid switch.
Newer stoves made ofter 2013 do not have a lid switch. Instead, the location on the stove from where the pressure switch monitors the vacuum pressure was moved so that if the hopper lid is opened, the feed system's power is cut. Harman realized that the pressure switch and the lid switch on the same circuit is a redundancy and were able to engineer the stove so that the pressure switch can meet the ASTM Safety Standards (achieve both functions) with only one switch.
Product Updates - Harman Technical Bulletin - August 2013
PELLET STOVE HOPPER LID SWITCH REMOVAL
In the continual process of product improvement and compliance with current standards, all Harman pellet stoves will have the hopper lid switch removed from their designs by the end of June 2013. The removal of the hopper lid switch from the pellet stoves simplifies the wiring and construction of the unit while also making the stove easier to troubleshoot in the field. Although the switch is no longer an ASTM requirement, the hopper lid must still remain closed during normal operation to ensure safe, airtight conditions. All newer Harman products without this switch have been engineered to stop the feed cycle via a different process when the lid in open during operation.
Effected Models:
- XXV Serial # 8214413 and higher
- P38 Model Discontinued
- P43 Serial # 8164487
- PC45 Serial # 8056231
- P61A Serial # 8092317
- P68 Serial # 8293174
- Advance Discontinued
- P35i Serial # 8654713