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Is there any rational reason for 9 cycles per hour pre programmed in emergency heat for an air/air

Had to switch to emergency heat (bad outside fan motor). Unit is an air/air trane heat pump. The electric heat is one 10kw heater which worked well but the tstat (TCONT802AS32DA) was pre-programed to cycle the air handler and the electric heat 9 times an hour. Drove the customer crazy. My question is, what is the downside to changing the cycles per hour option on the stat? On line searches seem to agree with 9 to 12 cycles as a manufactures recommendation. Just can't see why anyone would want the equipment to cycle this often?


  • Fred
    Fred Member Posts: 8,541
    It likely doesn't cycle 9 times in an hour, unless the structure is really leaky. Each "cycle" just tightens up to amount of indoor temp swing before the Tstat calls for heat. The more "cycles" programmed in the Tstat the more even the indoor temp should remain. However, I'm not sure what effect reducing the number of cycles will have on the load it places on the heater with each cycle. May require more recovery than the heater was designed to handle???
  • unclejohn
    unclejohn Member Posts: 1,830
    I would set it back to 4 or 5 at most. I have never seen a default setting of 9 per hour.
  • unclejohn
    unclejohn Member Posts: 1,830
    9—9 cph used for electric
    forced air heat systems
    (electric auxiliary heat for heat
    pump systems).

    Would not have believed it of I hadn't seen it. I guess leave it there I'm not gonna argue with Trane.
  • ratio
    ratio Member Posts: 3,408
    Short cycling isn't a concern with electric that it is with a fuel-burning appliance. You can cycle it as fast as you want to avoid large swings.

    There's no harm in turning the cph down. I usually leave it at 9, but I'm generally running the fan on continuous (commercial work), so no one really notices.

    JUGHNE Member Posts: 10,581
    I agree that if it is a short term temp heating situation for the customer, then the fan on cont might be tolerable.
    Anyone with HP should be used to a lot of fan activity.