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.