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Hyper heat not reaching heat set temp if below 35

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day2dive
day2dive Member Posts: 2
edited December 29 in A-C, Heat Pumps & Refrigeration

i have a new Mitsubishi SUZ-AA36NL heat pump that will not maintain or reach set temp if outdoor temp is 35 or lower .
the air handler is SVZ-AP36NL. My installer has been out twice, once found thermostat wired wrong, the other time said a wiring issue with AH. Neither has “fixed” the issue.
go to bed ..set at 72; indoor temp 74( using fireplace at night)

Wake up to 65 , unit running all night , outdoor temp 30.

TIA for anything I can suggest to them

Comments

  • Ironman
    Ironman Member Posts: 7,871

    It’s probably not charged correctly. There are strict guidelines in the installation manual for how much additional charge is required depending on the indoor unit(s), branch box(es) line set lengths, etc. Most installers have trouble with them, but the distributor can also calculate them with Mitsubishi’s Diamond software if given the correct info.

    The only way to properly charge the system is to weigh the correct amount in; it can’t simply be “topped off” by guessing or taking superheat and sub cooling readings.

    If the contractor has already added refrigerant, but didn’t do it using the proper calculations, then it all has to be removed and the proper amount weighed in based upon the proper calculations.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    day2dive
  • Big Ed_4
    Big Ed_4 Member Posts: 3,368

    Do you have the option for an auxiliary back up ? I will always recommend for the cold nights ….

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  • Big Ed_4
    Big Ed_4 Member Posts: 3,368

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  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,621
    edited 12:58AM

    Another unhappy HP customer.

    @day2dive where are you located? Cold climate?

    Steamhead
  • day2dive
    day2dive Member Posts: 2

    not particularly cold climate…Tennessee……

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,621

    I would think a HP should work in Tn.

    I would call the service manager or the owner and have a heart to heart with them. You paid for something that should work and it doesn't. Since it fails below 30 I am guessing in may be a defrost issue but my guess means nothing. They need to go through the unit and make it right. Mitsubishi is good equipment if installed right.

  • Hot_water_fan
    Hot_water_fan Member Posts: 2,240

    Call them back, they need to fix it. I have a hyper heat that works when it’s below 10F.

  • yellowdog
    yellowdog Member Posts: 279

    This all comes down to what is your heat loss versus the output of the air handler at the temperature you say it stops working at. Without this information, you will just be guessing at a fix. You need a heat loss done on the space the air handler serves and a diamond system builder report of what the output of the system is so you can see if it is a capacity, installation or charge issue.

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