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water leaking from PTHP

We are having a water issue with an Amana through the wall heat pump model# pth153b35ae.The bottom of the unit has rusted through, and the customer has agreed to replace the unit.My issue is the unit is producing water a lot when it is in the heat pump mode,very little when it is in the ac mode.This past week the customer had a pan under the unit ,the unit was only operating in the heat pump mode, there was no rain, and the customer dumped 6 pints of water out from under the unit that had collected in the pan.I am trying to understand the reason the unit would produce this much water in the heat pump mode,and I am not sure if it is because the condenser and evaporator are so much closer in this unit in compared to a conventional split system heat pump.Any assistance would be much appreciated.thanks to all.


  • Jamie Hall
    Jamie Hall Member Posts: 22,172
    The unit -- like any other heat pump or air conditioner which is air to air -- will always produce condensate at the evaporator; when it is operating in heat pump mode, that evaporator is handling outside air. If that air is humid, relatively speaking, you could be getting a lot of condensate that way.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • zepfan
    zepfan Member Posts: 390
    Thanks, take care
    JUGHNE Member Posts: 10,914
    In heating mode the outside coil will frost/ice and goes thru maybe a defrost reverse cycle or just shuts down at low amb. If you have low amb shut down and your ODT just falls below that over night and you are above freezing during the day the coil could defrost and the melt down could be what your seeing.

    Of course the sleeve should tilt out for drainage. Some PTHP have an auto drain in the outdoor pan, hot temp keep it closed for the fan slinger to throw the condensate up into the hot cond coil. In cold weather the drain opens to relieve the defrost water.
    This drain is some form of bimetallic or such and no power is needed. It, if there, may have failed or just be plugged with dirt.
  • zepfan
    zepfan Member Posts: 390
    thanks. we have since replaced the unit, and it is graded to the outside slightly now, and we installed the outside condensate kit.I have seen the auto drain that you refer to on some units,but did not see anything like that on this unit.take care.