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Thread: RTH9585WF heating based on exterior temperature

  1. #1
    Junior Member

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    RTH9585WF heating based on exterior temperature

    Hello all,

    The question might've been asked before but I don't know the heating vocabulary so here it is:

    I have a new Honeywell thermostat RTH9585WF which replace my Alarm.Com thermostat (not connected) I have an Amana heat pump (at least 10 yo) and also have an electric furnace which replaced a oil furnace last year. My heatpump can't work when temperature is below -15C (5F) and since I'm in Quebec city, this is 4 months/year

    The thermostat I had was capable of switching to the furnace base on outside temp.
    How can I activate this with my honeywell thermostat?

    I suppose it's possible since if I request a high demand, like an increase of 2C, the furnace kick in instead of the heatpump, and when temp is reach, the heatpump take over.

    Thanks for your help!


  2. #2
    Senior Member

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    I don't think your new thermostat has that option. Give Honeywell support a call at 1 800 828-8367 to confirm.

    You can manually change to "emergency heat" to lock out the compressor but you'd lose the daytime advantages.

    A tried and true solution is a mechanical thermostat switch at the outdoor unit:

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