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Mitsubishi FH12

smokey059 | Posted in General Questions on

I noticed we have about 6 days coming with the daytime Temps around -10 and night time Temps -20. I have always just left the heat pump run when it has got below -13 but that was maybe a day or 2 at night with daytime Temps going above zero. 
It seems that these coming Temps will be at the very extreme for the heat pump.
Do you think I should turn the heat pump off and just plug in an electric heater or just let the heat pump run and see if it will heat? The apartment is only 800sf. and very well insulated and very air tight.

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  1. paul_wiedefeld | | #1

    Easy enough to keep the heat pump on and plug in the space heat in as well.

  2. smokey059 | | #2

    Do you know if it's hard on them working at those extreme temps

    1. paul_wiedefeld | | #3

      It's built to work at cold temperatures, I assume not.

  3. jwasilko | | #4

    Specs at\M_SUBMITTAL_MSZ-FH12NA_MUZ-FH12NAH-en.pdf

    Outdoor Unit Operating Temperature Range:
    Heating Air Temp (Maximum / Minimum) °F 75 / -13
    Heating Thermal Lock-out / Re-start Temperatures** °F -18 / -14

    So it looks like it will shut off at -18F and restart at -14F.

  4. smokey059 | | #5

    Thanks for the link. I was wondering if it would shut off when it hit -22 the next 4 days and I'll be watching to see if it does.
    When it gets really cold it seems to defrost every 45 minutes or so. I don't see any ice on the coils when it defrosts is this normal. It still keeps the apartment at 70 though even though it does the defrost cycle every 45 minutes.

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