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Honeywell TH8000 thermostat troubleshooting

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  • Honeywell TH8000 thermostat troubleshooting

    I have a heat pump/furnace combination. The system is set so that above 40 degrees, the heat pump is the heat source. Below 40 degrees, the furnace is the heat source. When the heat pump is in use, the system works perfectly. When the furnace is in use, the thermostat turns on the furnace at the appropriate time, based on the temperature settings, but will not turn off the furnace regardless of how hot it gets. Once the furnace is started, the only way of turning off the furnace is to turn off the power to the furnace. I don't know how to fix the problem.

  • #2
    Re: Honeywell TH8000 thermostat troubleshooting

    The off temp is set too high.

    The relay in the thermostat is sticking.

    The relay in the furnace board is sticking.

    The gas valve in the furnace is bad.

    Next time it happens - with the furnace still heating, remove the thermostat from the wall and set it someplace. Go look at the furnace - if it's running, the problem lies there. If not, the problem lies at the thermostat.

    ... it was plumbed by Ray Charles and his helper Stevie Wonder