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Thread: dead zone

  1. #1
    Join Date
    Jan 2008
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    dead zone

    I have a dual fuel hp amana /propane that is set to switch over to propane at 20 degrees It works great except for the fact as the outside temp begins to rise the propane keeps running untill about 27 degrees Is this normal

  2. #2
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    May 2000
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    Indianapolis, IN, USA
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    What control? A Vision Pro has a 5° deadband so it should rise to 25° before going back to pump.

  3. #3
    Join Date
    Jan 2008
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    The control is a rotating outdoor themostat my heat pump thermostat does not control the switchover to propane

  4. #4
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    Sounds like the differential is set that high.

    Its a little high then I would set. but, may be just what your installers standard setting is.
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  5. #5
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    What dfferential please explain

  6. #6
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    The stat is set to have a temp to switch to aux. And the differential is the amount of temp the outdoor air must rise before it switches back to heat pump.
    Non as either dead band, or differential.
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  7. #7
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    Dead Band I don’t know. Differential Yes

    DIFFERENTIAL - The difference between the cut-in and cut-out of a control.

  8. #8
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    Quote Originally Posted by pecmsg View Post
    Dead Band I don’t know. Differential Yes

    DIFFERENTIAL - The difference between the cut-in and cut-out of a control.

    Dead band.

    Area (temp range) of no change from previous function/condition.
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  9. #9
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    Jan 2008
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    thanks for the explaination. I am curious why does there need to be a differential of several degrees?

  10. #10
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    Jun 2006
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    Omaha, Nebraska
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    The outdoor temp typically fluctuates a few degrees all day long depending on cloud cover, wind direction, etc. With a low deadband (differential) of 1-2degrees the HP might be switching back and forth between gas and mechanical heat frequently when the outdoor temp is right around the setpoint. I would think a deadband of 4 degrees might be a little better. Your outdoor stat might have and adjustable differential or it could be non-adjustable.

  11. #11
    Join Date
    Jan 2008
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    19
    thanks all

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