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-   -   New Honeywell Thermostat for Heat Pump and Gas Furnace - not working (https://www.askmehelpdesk.com/showthread.php?t=280678)

  • Nov 13, 2008, 06:28 PM
    kywest
    New Honeywell Thermostat for Heat Pump and Gas Furnace - not working
    We recently bought a Honeywell RTH7400 for our home with a Goodman cple30-1 Heat pump and a Janitrol Gas furnace. I hooked it up according to the Honeywell instructions.
    C to C
    G to G
    Y to Y
    O to O/B
    R to RC with jumper to R
    W2 to Aux with jumper to E

    I set it to 7 on function 170 (multistage heat pump); 0 on function 190 and 5 on function 270 (for 80% gas furnace).

    When heat system is turned on and thermostat is set higher than air temp, the heat indicator comes on and the fan and heat pump come on - this lasts for about 60 seconds and then the Aux Heat indicator comes on and the fan stops running and the furnace seem to try to light but doesn't and then the heat pump runs without the fan.
    When the emerg heat system is set, the furnace does the same thing and the fan does not run. The fan runs at other times when it should and if I set the system to heat pump only - it works OK (but has trouble keeping up when the weather is cold). Honeywell insists that it is set correctly and there is something wrong with the system. However, I had a HVAC tech out to check it over (when I tried to install the 1st thermostat that was broken) and they said the system was fine. Before I have them come out again, is there anything I can do?
    Thanks.

    Kris
    Westerville OH
  • Nov 13, 2008, 09:10 PM
    dac122

    If you wire the original thermostat back in does the system work correctly?
  • Nov 13, 2008, 10:13 PM
    KISS

    This is a dual fuel system guys. Most stats can't handle it.
  • Nov 14, 2008, 05:15 AM
    kywest
    Thanks
    Did not try the original thermostat; will try that tonight.
    Honeywell and Home Depot both swear this thermostat should handle the dual system.
    Any thoughts?
  • Nov 14, 2008, 06:25 AM
    dac122

    KeepIt, not sure why you'd say that here is the manual. I was just holding this model in my hand at homedepot yesterday and I'm pretty sure the back shows it will do what is needed here.

    kywest, my thinking is I'd like to verify there isn't something wrong with your system first. Once you have the old tstat connected, using a multimeter verify which wires are energized in each mode: heat, cool, aux heat, fan only, heat with extra call for aux heat. Run it through its paces. Remember some HPs have a lockout when switching modes or when first energized as a safety, so be patient. Then you can be sure which wire does what.

    From what you've described it sounds like everything is wired up correctly based on colors and labels and the config is close enough - not sure if 190 is correct, but you shouldn't see this kind of behavior.

    Let us know what you find, and post the wires colors energized in each mode.
  • Nov 14, 2008, 08:04 AM
    KISS

    West:

    Take a look at hear at some of the honeywell models. I use this page because it's so much nicer to navigate. Honeywell VisionPro Thermostats - iaqsource.com

    There are specific models on this page which will do dual fuel. Setup will get messy.

    Pay particular attention to the ways that lockout happen. It might not be totally obvious, but with an outdoor sensor, there is less fiddling. With an has furnace, you normally don't want the HP and the gas to be on at the same time. With the outdoor sensor, you can pick that point where the switch occurs.

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