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  1. #1
    Join Date
    May 2008
    Location
    Distant NW 'burbs of Chicago
    Posts
    42

    Heat Pump start after Elec Power Failure

    We have a new Trane XL16i heat pump system, 4 ton, 410A. I'm wondering what would happen if we were out of town during winter and had an electrical power failure for maybe 48 hours with the outside temperature around 0'F. The house is very well insulated and would not freeze the pipes during that time; but the heat pump would start as soon as the power came back on.
    I've been told that most systems have a sump heater to keep the refrigerant from getting too cold and damaging the compressor, but that heater would be inop during the power outage.
    Is there danger of damage under those conditions?
    If so, is there anything I can do to protect the system?
    Thanks!

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,082
    It would be possible for damage to occur.

    You could set your stat to emergency heat, and to its lowest temp setting.
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  3. #3
    Join Date
    May 2008
    Location
    Distant NW 'burbs of Chicago
    Posts
    42
    That makes sense, but...
    Using emerg heat only would be pretty expensive if we were away for a long period, like a month or two;
    and
    If we keep the thermostat set at a low indoor temp to save some of that money, then the pipes will freeze up sooner if the power stays off too long.
    Any other possibilities?

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,082
    Earlier, you said the pipes wouldn't freeze in 48 hours.

    The elcetric bill would be cheaper then the house damage from frozen pipes.

    Your best bet.
    Is a trusted neighbor.
    No home should be left unchecked for a month, winter or summer.

    Next thing, is you can get one of the security services that can also monitor the homes temp.

    Or a big generator that can power your heat pump.
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  5. #5
    Join Date
    May 2008
    Location
    Distant NW 'burbs of Chicago
    Posts
    42
    This evening I was talking with the installer, the area Trane tech expert has told him that the XL16i has a scroll compressor that seems immune to cold refrigerant startups. I have no way to check the accuracy of that information.

    If the power goes off for more than 12 hours while we are home, we can trip the CB for the compressor. Then when the power comes back on, set the thermostat to Emergency Heat only and reset the compressor CB so the sump heater will start working. Run on Emergency Heat for a few hours until the refrigerant is warmed up and put the thermostat back in Normal heat. That works for me but I'm not sure the neighbors would get it right, even with a written checklist. Hopefully, the tech guy is correct about no damage.

    We do plan to get one of the telephone temperature monitors.

  6. #6
    Join Date
    Oct 2006
    Location
    Emerald Coast, FL 30.1N 85.8W
    Posts
    681

    If power failure occurs..

    A sudden power outage or turning your t stat off & then on causes the compressor to start on locked rotor amps -- this can cause the comp to shut off on overload -- Shutting off the disconnect & then turning it back on 6 months later does the same thing -- always turn off your t stat before resetting breakers.

    The compressor needs voltage to activate the compressor heater -- so if any of the above conditions occur, you need to have voltage to the outdoor unit for several hours before you start it up, or you could damage it with the comp starting with liquid in it -- not good.

    I've made a few well-established HVACR companies look stupid because of these reasons -- I took their customers & gained about 10k extra PM work a year.

  7. #7
    Join Date
    May 2008
    Location
    Distant NW 'burbs of Chicago
    Posts
    42
    I think that's the same idea I was trying to say in my previous post, biggest problem would be getting someone who doesn't understand the system (wife or neighbor) to do it if I'm not here.

  8. #8
    Join Date
    Nov 2004
    Location
    Austin, TX
    Posts
    877
    A possibility of damage, yes. Whether it's a high probability, can't tell.

    To eliminate that possibility have your servicing company install a delay on make timer.
    Here's one with a range of 1 second to 100 hours.
    http://www.ssac.com/catalog/CT-ERD.pdf
    It could be set for several hours delay after power is restored.
    I can think of several different ways to install it, none are do it yourself.
    Several ways which would create troubleshooting nightmares later on.
    This timer isn't the cheapest one on the block but is the first one I've seen that will handle time in hours.
    Of course you need to remember to set it back once you returned.
    And of course anything extra you have installed is just something else to break.



    Quote Originally Posted by Gearhead Jim View Post
    We have a new Trane XL16i heat pump system, 4 ton, 410A. I'm wondering what would happen if we were out of town during winter and had an electrical power failure for maybe 48 hours with the outside temperature around 0'F. The house is very well insulated and would not freeze the pipes during that time; but the heat pump would start as soon as the power came back on.
    I've been told that most systems have a sump heater to keep the refrigerant from getting too cold and damaging the compressor, but that heater would be inop during the power outage.
    Is there danger of damage under those conditions?
    If so, is there anything I can do to protect the system?
    Thanks!
    I am for doing good to the poor, but...I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it. I observed...that the more public provisions were made for the poor, the less they provided for themselves, and of course became poorer. And, on the contrary, the less was done for them, the more they did for themselves, and became richer.
    ― Benjamin Franklin

  9. #9
    Join Date
    May 2008
    Location
    Distant NW 'burbs of Chicago
    Posts
    42
    That should work, thanks. Installation would be complicated by the fact that we need to power the sump heater without powering the compressor.
    I'm leaning toward the idea of "Give the neighbors a house key and re-start instruction sheet, keep my fingers crossed" method.
    EDITED TO ADD:
    Especially since I have a 10 year warranty and they've told me not to worry about the effects of a power interruption. It's their baby.
    If I can find an easy and simple way to protect the compressor more, I'll do it. But only if it's easy and simple.

  10. #10
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    Timer would not cause a problem with the "heater" if wired properly. I would think the max delay needed would be 8 hours. Call you Trane dealer and bounce what you've read here off of him
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  11. #11
    Join Date
    Mar 2003
    Location
    PA/DE area
    Posts
    1,535
    Remember SNOWBALL??How many years did they slug it with liquid before it died??I know it was r-22 ,but still it was orange.
    It's NOT the BRAND,it's the company that installs it!!!!!

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,082
    Around 27 years.
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    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584
    Here is a solution to your problem,and it will work everytime and keep your Trane heat pump running even if your not there.

    Solution- http://allenselectric.com/whats_new.html
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

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