Possible thermostat problems

[Lord Whorfin]

Greetings, all. New problem: Furnace in Manual light, Auto mode. Last year, when I turned the thermostat down, furnace would note that heat was not being called for and only feed enough pellets to keep small fire going, and the main blower would stop running but exhaust fan would keep running.
This year I had trouble lighting, but traced to bad exhaust temp probe, but also replaced board before finding it was the probe. Dip switchsd were set according to instructions with the new board.
Now, furnace maintains the same level of operation, no matter where thermostat is set- set at minimum, and temp control on board set to #1-
Furnace never cools down enough for blower fan to stop.

Thanks in advance for any help you all can provide.

Harman PF 100
Use about 9 tons per year

 

[Whitenuckler]

Greetings, all. New problem: Furnace in Manual light, Auto mode. Last year, when I turned the thermostat down, furnace would note that heat was not being called for and only feed enough pellets to keep small fire going, and the main blower would stop running but exhaust fan would keep running.
This year I had trouble lighting, but traced to bad exhaust temp probe, but also replaced board before finding it was the probe. Dip switchsd were set according to instructions with the new board.
Now, furnace maintains the same level of operation, no matter where thermostat is set- set at minimum, and temp control on board set to #1-
Furnace never cools down enough for blower fan to stop.

Thanks in advance for any help you all can provide.

Harman PF 100
Use about 9 tons per year

I have a P43, but it sounds like the same operation. I don't use a thermostat. I extended the probe. I do know that people use thermostats but they need to wire them in series with the probe. I have don't use that mode. I imagine you need to keep the temp dial all the way up to use an external thermostat. Then when the thermostat opens up the room temp probe you get xxx blinks and it either shuts off, or maintains the flame. I'd check all the wiring and make sure the thermostat works with a meter. Can you go back to the old board? Is the color of ESP probe wires the same as before?

 

[Lord Whorfin]

Hello, Whitenuckler- thanks for the reply. The thermostat is a Harman-specific item, that adjust the size of the fire based on difference between room temp and thermostat settings. I have it turned all the way down, so the temp difference is about 10 degrees between them setting and room temp. I have a new thermostat from Harman, but I'm paranoid about changing another thing without knowing it is the problem. I guess the only way to find out is to do it, but hoping someone will have a better idea. Thanks again for your help.

 

[Whitenuckler]

Hello, Whitenuckler- thanks for the reply. The thermostat is a Harman-specific item, that adjust the size of the fire based on difference between room temp and thermostat settings. I have it turned all the way down, so the temp difference is about 10 degrees between them setting and room temp. I have a new thermostat from Harman, but I'm paranoid about changing another thing without knowing it is the problem. I guess the only way to find out is to do it, but hoping someone will have a better idea. Thanks again for your help.

That does not make sense to me. I would crank the stove temp dial to max if using a thermostat on my stove. That assumes its mounted in the same room. I'm not sure about how yours works, but that is the way it would work for a pellet stove like mine.

 

[Whitenuckler]

That does not make sense to me. I would crank the stove temp dial to max if using a thermostat on my stove. That assumes its mounted in the same room. I'm not sure about how yours works, but that is the way it would work for a pellet stove like mine.

https://downloads.hearthnhome.com/installmanuals/pf100.pdf I will have to go over the manual to learn