Harmon P68 room temp sensor flaky

[tpavlick]

Greetings all. I got the unit in the middle of last winter and it seemed to act ok last year, although I noticed sometimes in a big outside temp fluctuation I had to futz with the temp.

I operate the stove in full auto mode, with the heat set at 70 on the dial.. and it mostly works - however, I have had mornings where it was 40 overnight and the house is at 78, or conversely, it's at 60 and the stove is not turning on. I have been able to (in my mind) reset this by turning the fan dial off, then turn it back on and it seems to be better. Other times I have to just feather touch the temp knob and the stove turns on.
Without any other real TS, I am assuming either the temp probe is relaying the wrong temp or the knob or its solder joints are flaky.
Your thought or experiences would be appreciated. TIA

 

[Montecarlossfan]

If you are able to change the stove’s behavior by lightly touching the knobs , the potentiometers are either shot or “dirty”. If you ever had an old stereo crackle when adjusting volume this is essentially what is happening. You can try to clean them using deoxit , install new ones (if you like to solder and are good at it) or replace the board.

 

[bogieb]

My P61a developed a "dead spot" on the temp dial and had a similar issue. Not being electrically inclined (and knowing that I could mess up anything), I declined try to fix it. It wasn't worth the cost of a new board either and again, installing it was not womething I wanted to tempt fate with. So, I installed an exterior thermostat. I bought a pretty basic battery operated Lux (same one I already had on my P43 so I knew worked well) - I think it was $22.

I had already been thinking about the thermostat option anyway, the issue just made it more of a priority.

That being said - are you sure your air temp probe isn't being affected by a draft or too close to a wall? With the stove acting opposite of the outside temp, that could be the culprit. I'm sure you already thought about futzing around with that - I just like to point out the potential free fixes first.

 

[tpavlick]

Thanks all.. I just ran by the dealer and he gave me a warrantee swap on the temp probe.. I just attached it and will watch as the temp drops from 75 to 38 overnight tonught. Weird outside temp fluctuations this time a year in Upstate NY, guess it happens in a lot of places.

I did consider doing the external thermostat as well. Curious, I didn't test the connectors yet but does the Harmon output enough voltage to run a remote sensor or do you need to provide power to it / or batteries?

Anyway, since it's a year old and under warrantee, I want to keep it going for two more years before I start out of warrantee mods.

I'll post back in a few days, we are supposed to fluctuate between 32 and 60 for the next 3 or 4 days, we'll see how it works with this change.

 

[tpavlick]

Tech just arrived and connected a test box and saw that it read the room at 67 and the set point on the stove was 70... touched the temp dial and it turned on. It looks like it's the board, he replacing it now. Boom !

 

[Mt Bob]

Tech just arrive and connected a test box and saw that it read the room at 67 and the set point on the stove was 70... touched the temp dial and it turned on. It looks like it's the board, he replacing it now. Boom !

Save your board, it can be simply repaired. Then you will have a spare.

 

[bogieb]

Thanks all.. I just ran by the dealer and he gave me a warrantee swap on the temp probe.. I just attached it and will watch as the temp drops from 75 to 38 overnight tonught. Weird outside temp fluctuations this time a year in Upstate NY, guess it happens in a lot of places.

I did consider doing the external thermostat as well. Curious, I didn't test the connectors yet but does the Harmon output enough voltage to run a remote sensor or do you need to provide power to it / or batteries?

Anyway, since it's a year old and under warrantee, I want to keep it going for two more years before I start out of warrantee mods.

I'll post back in a few days, we are supposed to fluctuate between 32 and 60 for the next 3 or 4 days, we'll see how it works with this change.

The stove does not run the external thermostat. The one's I use are battery operated. When I replaced my boiler's thermostat, one of those old dial - probably the original when the house was built in 1960, I used the same model. So now I have 3 of the exact same type.

It is non-programmable, but I don't need that or any connectivity with my phone. I do appreciate that it has a one-push button that will lower the set temp by 5*. Then push it again and it resumes the original set temp.

Tech just arrived and connected a test box and saw that it read the room at 67 and the set point on the stove was 70... touched the temp dial and it turned on. It looks like it's the board, he replacing it now. Boom !

Great that the problem was found, and even better that it was a fix under warranty