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Thread: advanced setttings and aux heat.

  1. #1
    Junior Member

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    advanced setttings and aux heat.

    I've been considering purchasing the Wi-Fi Thermostat 9000 based on the recommendations of others on this site and elsewhere.

    My question is does anyone know what is the outdoor low temperature setting is for the aux heat to kick in and stop the heat pump? and can it be adjusted?

    Right now my system kicks in the aux heat at -10 C (14F) and the heat pump will not come on. I have an older heat pump and the efficiency is not as good as the newer systems so any temperature below -10 is just a waste of electricity for it to be running.

    With my current Honeywell thermostat I am able to adjust this temperature switchover.



    Thanks for any help!

  2. #2
    Administrator

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    There is not a adjustable switch over setpoint in the menus of the Honeywell 9000. I call Honeywell and they said that the setpoint is not always the same. They said the switch over setpoint is dependent on several conditions. I asked them to explain the conditions and algorithms and they said they did not have that information available.

  3. #3
    HVAC Thermostat Specialist

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    You really would need a higher end thermostat to control an aux lockout temperature.

    As far as your comment that it would be a waste of energy to run the HP below -10C is not true. You will always (no matter what temp it is outside) get more heat out of the HP then what you put in. You should research Heat pump COP.

    A heat pump will generally produce 2-4 units of heat per 1 unit of electricity. Electric strip heat produces 1 unit of heat per 1 unit of electricity.

    Click image for larger version. 

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  4. #4
    Junior Member

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    hvactechfw: That's a great comment and chart. It's impressive that the COP is greater than 1.0 down to a temperature of -25F.

  5. #5
    HVAC Thermostat Specialist

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    The chart is for reference only as each HP is different and beyond that it depends upon installation and other factors such as maintenance performed on unit.

  6. #6
    Junior Member

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    thanks for the input guys.

    I have the Honeywell VisionPro 8000 and it does switchover to aux heating at -10 (I never had to adjust this setting).

    I was just curious if the 9000 did the same.

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