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Furnace continuously calls for heat

Brian11 Member Posts: 1
I have a White Rodgers gas furnace and thermostats from approx 1965. I (me as well as plumbers) have tried to update the thermostats several times. Every time a new thermostat is connected the system continuously calls for heat and does not stop. Any ideas on what is causing this?


  • Jamie Hall
    Jamie Hall Member Posts: 18,947
    Something amiss in the wiring. Have you verified what each wire is and what it does? Is this two wire or three? And don't assume, if it is three, that you have the same colour at both ends of the wires. You may have, for example, white, red, and yellow at both ends -- but it's perfectly possible that somewhere in between somebody spliced them oddly, and that the colours at one end aren't the same as those at the other.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ironman
    Ironman Member Posts: 6,868
    Is it a milivolt system?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    EBEBRATT-Ed Member Posts: 12,007
    If you can post a few pictures of the wiring and controls we will try and help

    On the + side at least you have heat.

    just to be safe I would shut the boiler or furnace off at the service switch and see if the burner shuts off and then turn the power on to restart

    Just to be sure you don't have an unsafe runaway condition
  • newagedawn
    newagedawn Member Posts: 586
    usually means the t stat wires are shorted, time to pull a new one, did you ohm it out?
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"