Harman P61-A rises to 75 in room and stays there

chrisby18951

New Member
Nov 22, 2018
2
Quakertown, Pa
purchased in 2005 and has been flawless until late last season. If I start it at say 66 degrees it stays for a bit but over the next 12 hours or so it slowly rises to 75 and stays there. Ive changed the ESP and room temp sensor. Any other ideas before I replace the main control board? It runs fine otherwise. Contemplating adding a setback thermostat and switching the igniter switch to manual and letting it go in maintenance mode if the temp is higher than I want. Thanks in advance for any help!!
 

jackman

Minister of Fire
Jan 15, 2013
528
Oregon
I'd run the self test to see if that shows anything. Then I'd run it for a day or two on Stove temp mode and see if it holds the temperature steady.
 

chrisby18951

New Member
Nov 22, 2018
2
Quakertown, Pa
I'd run the self test to see if that shows anything. Then I'd run it for a day or two on Stove temp mode and see if it holds the temperature steady.
Self test seemed normal. But now it won’t shut down at all, even with the knob to the off position. Funny thing is my Dads p61-a has the same issue. His is a year newer. A repair guy disconnected all the sensors and replaced his control board and his still won’t shut off reliably. He says the only thing left is to replace the wiring harness. We did both replace the ESP at the same time with what I’m thinking were not OEM probes. We both had the same isssues and that’s why we replaced the ESPs. So if anyone can help us it would we be appreciated by both of us!!