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Cut breaker power to gas furnace & AC during their off-seasons?

RandyK9 | Posted in General Questions on

I live in Buffalo, NY which has hot summers and cold winters. So once winter breaks in April or May, I never run my furnace until Nov 1. Same with AC. After Nov 1, I wont be needing AC until May at the earliest most years. Is this a good idea?  I cut the breaker power off to my pool outlet during the whole winter. Any issues with cutting the power on a forced air furnace or forced air AC for 6 months? Will it save electricity or have any other benefit or detriment?


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  1. Expert Member
    BILL WICHERS | | #1

    Is your AC seperate from your furnace air handler, or are you asking about just shutting off the power to the outdoor compressor unit? Most residential forced air HVAC systems use the same air handler for both cooling and heating, so you generally can’t seasonally shut off the indoor unit.

    It’s not usually a problem to shut off the outdoor compressor in the off season, but it’s not likely to save you anything unless you have a compressor heater.


  2. Expert Member
    NICK KEENAN | | #2

    Unless you have a real antique with a pilot light they're not going to use any standby energy. If you're worried about them unintentionally running (say on a cool night) turn off the thermostat.

    Some boilers keep the boiler at a minimum temperature even when it's not calling for heat. It's a controversial subject whether they should be turned off in the summer. I turn mine off but some people believe the thermal shock of cooling to room temperature lowers the longevity of the boiler.

  3. joshdurston | | #3

    Some AC compressors have a heater, I would power it up for a couple hours minimum before you turn it on, especially in cool weather. You don't want liquid refrigerant hitting the compressor if you can avoid it.

    Personally I turn the equipment disconnects off seasonally, and have been doing so without any unexpected consequences. I do it at the disconnect, and not the breaker though. I try not to cycle my breakers more than I have to.

    1. Expert Member
      BILL WICHERS | | #4

      Josh, you’re probably better off cycling your breakers than a disconnect in many cases, especially if your “disconnect” is an old-style pullout fuse block. The blade-type contacts in those fuse blocks, and some disconnect switches, are likely to wear out before the contacts in a typical circuit breaker which has internal contacts more like those in a relay.

      It’s actually recommended to cycle circuit breakers at least once annually although pretty much no one actually does that.


  4. walta100 | | #5

    Turning off the breaker for the indoor part of the system will save you very small amount of electric for the few months in between the heating and cooling seasons and in my opinion not worth the effort.

    Turning off the breaker to the outdoor part of an AC unit will sometimes save 50-200 watts by shutting down the heater in the compressor. If you do this do so knowing that the heater is there for a reason and you must be careful when you restart the system. In my opinion you should not operate the AC unless the breaker has been on for at least 24 hours. The heater is there because refrigerant in the system will move to the coldest point in the system in a liquid form. If the compressor happens to be the coldest spot and the compressor turns on. The compressor may pick up liquid and try to compress the liquid since it is not possible to compress a liquid the compressor is very likely to be damaged should this happen.


    1. RandyK9 | | #6

      That's great advice Walta. I did not know this. Is there a danger if the AC unit breaker/heater is off and thus frozen solid for a 2-3 months? (We can have very cold Jan-Feb here [Below 20 for those 2 months]) on a bad winter here. Also, is my math correct?
      13 cents per kWh x 200 watts = $26

      1. Expert Member
        BILL WICHERS | | #7

        200 watts is 0.2kw, so 0.2kwh for every hour it’s running. At 13 cents per kWh, that works out to $18.72/month.

        The refrigerant won’t freeze solid in winter temperatures. The only issue is that if the compressor tries to run while there is liquid refrigerant present in the compressor you risk damaging the compressor. You can avoid that issue by letting the unit warm up for a while prior to using it when the cooling season starts.


        1. RandyK9 | | #8

          That makes sense. Thank you!

        2. Expert Member
          Akos | | #9

          I've only ever seen compressor heaters on heat pumps. Standard AC units won't have anything in them. They also have no electronics and consume no power when off.

          More modern inverter based units have a lot more electronics and are the ones that can have a fair bit of standby use, those are sometimes worth while to turn off.

  5. brad_rh | | #10

    FYI. My 3 ton Am Std heat pump was still using about 700 Wh per day for compressor heater on May 21 before I shut it off. It was cycling on even during the day when it was probably in the 60's.

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