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Honeywell TH5220D thermostat forgetting settings and possibly causing damage

ukiltmybrutha Member Posts: 30
This thermostat keeps forgetting it's settings to include the heating type. It lost the heating setting recently and the fan motor went bad at the same time. Too much of a coincidence for my liking.

Is there anything inherently deficient about these unit as to why it might do that?

I believe it takes 2 AAA batteries. Shouldn't this unit show low charge when batteries die?

Looking for pointers or experience with this unit. I could replace the unit with a better type, but my setup is simple and I'd like to stay in budget.



  • Jamie Hall
    Jamie Hall Member Posts: 21,090
    No, when the batteries are about to die it may just go to a blank screen. There is a battery warning indicator, though, which should give you a few days warning. I presume you don't have a C wire?

    There is no way the thermostat can cause a fan failure The thermostat is basically a simply on/off switch.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ukiltmybrutha
    ukiltmybrutha Member Posts: 30
    Thanks, let me see if I do or don't have a c wire.
  • ratio
    ratio Member Posts: 3,402
    It's not worth fiddling with a stat. Replace it if it's suspect.
  • ukiltmybrutha
    ukiltmybrutha Member Posts: 30
    Thanks, will check to see if I have a C wire and then get rid of this thing!