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  1. #1

    curious question about duration of cycle on heat pump

    the outdoor ambient temperature is below freezing, as low as 28F, average around 30F
    indoor target 64F (set away), looks like heat pump is keeping up with the heat.

    i am seeing a consistent, repeating pattern of heat pump cycle on 16 minutes , off for 30 minutes, then cycle on 32 minutes (2x longer), then off for 30 minutes, then cycle on 16 minutes, then off 30 minutes, then cycle on 32 minutes. it seem to be a repeating pattern.

    i am away from home, can't tell if compressor is in deep defrosted cycle and blower kept blowing cold air into house, according to the log, it seem like indoor temperature drop 1F during that same time, but if it is defrosting, why is it only happening every OTHER cycles?

    i don't have heating strip, the aux heat is propane furnace, and the DIFF is 3F.

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  2. #2
    Join Date
    Aug 2012
    I would say it is defrosting because the colder it gets the more ice builds up
    My name is TooCoolforschool and I am a chronic over charger.

  3. #3
    Join Date
    Feb 2009
    Tallahassee, FL
    What kind of thermostat is this?

    What kind/model of outdoor unit is it?

  4. #4
    the thermostat is Filtrete 3M50 from homedepot, swing is set at 1.0F, DIFF 3.0F
    outdoor unit is Gibson JT4BD-048K
    indoor coil Gibson C7BAM0480C-C

  5. #5
    Join Date
    Feb 2009
    Tallahassee, FL
    Ok I'm not real familiar with your equipment however I may have some insight.

    The outdoor unit probably has time/temp defrost and may be set to defrost every 30 mins of run time.

    This seems to be what your graph displays.

    When you get back to house you may have a tech adjust interval if you want to fine tune it.

  6. #6
    i did asked my installer, and he said this unit has auto defrost with sensor.
    i am leaned more toward to low temperature and high humidity at the time.
    this defrost cycle has stopped around 12 noon today.
    i will go home soon, so i just raised the temperature by 2F, and it seem like heat pump ran for 30 minutes and reached the target with out any drop of indoor temperature while the whole time HP was running,
    today weather, full sun since 10am this morning, at 3pm currently 31F sunny, NW 10mph wind, 35% humidity.

  7. #7
    Join Date
    Jul 2007
    Quote Originally Posted by bronzemaxell View Post
    i did asked my installer, and he said this unit has auto defrost with sensor.
    That must be layman's terms for a Time/Temperature Defrost, because as SBKold said, that is what this unit has.

    This unit comes from the factory pre-set for a 30 min. defrost cycles when the coil temperature is < 32f.

    It sounds like the installer made no adjustment to the factory setting.
    Instead of learning the tricks of the trade, learn the trade.

  8. #8
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 01-18-2013 at 07:35 PM. Reason: non AOP member

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