My wife and I purchased our first home this past year and we did a bunch of repairs up-front via a rehab loan, and one of the things we replaced was a very old thermostat with a new digital one.

I had a licensed HVAC friend walk me through the installation and after install it seemed to be working just fine (ie. fan turns on, furnace fires up, house gets hot) but now that its been colder we've realized that the heater and AC don't automatically turn off when the temperature reaches the what we set it to.

I didn't think anything of it because we never set anything on the thermostat other than the time & day, but i'be been reading online that the thermostat brand we bought is apparently known to fail.

My question is, how can I tell if my thermostat is faulty when it does everything except turn off at the temperature we set?

For reference, my heater is a Rheem Criterion II and the thermostat is a Hunter 44260.

  • Are you saying that the heater or AC stays on for hours, continuously?
    – Jay Bazuzi
    Jan 29, 2011 at 18:17
  • I can manually turn it off with the switch on the thermostat - but it does not automatically switch off based on the temperature we set for it. For example, this morning I set it to 73 degrees, turned the fan on auto and turn the setting to heat. The heater kicked on and when I came back a about 20 minutes later the temperature was 80 degrees!. I want it to stop when it gets to the temperature I set and turn back on if it dips more than a few degrees below my setting.
    – drewdah
    Jan 29, 2011 at 18:30

2 Answers 2


If you can stop the heat using a switch built into the thermostat, then I'd guess you've wired it correctly and your problem is that it's defective. You should call the thermostat manufacturer and describe what's going on; they'll probably send you a new unit under warranty.

  • Thanks for the confirmation. I'm still under my one-year warranty from Hunter - is it worth having them replace it with another Hunter unit or should I just bite the bullet and get a different brand?
    – drewdah
    Jan 31, 2011 at 5:59

If the room temp registering on the thermometer function is much higher (80 for example) than the thermostat set temp,(72 for example) chances are good that you have a defective unit.

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