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HEAT PUMP Lennox HP 29-048-4M

Chandler87 Member, Email Confirmation Posts: 1
Hello! Can tell at what temperatures it will work. I bought a house in state Maine and the Lennox HP 29-048-4M system is installed in it, tell me at what temperatures it will work in winter, it can be very cold here at winter. The local dealer could not answer this question. Thanks!


  • pecmsg
    pecmsg Member Posts: 4,883
    I theory it is always more efficient then straight electric heat at all temperatures but, add in defrost, snow / rain that # changes. Eastern LI 20°F and we switch to the back up source.

    Every building is unique so an exact # is difficult at best.
  • Jamie Hall
    Jamie Hall Member Posts: 23,426
    Unfortunately -- but typically-- the reduction in COP with temperature is not published -- which is the what you really need. If you are along the shore in Maine, particularly somewhere up near Portland, it will probably work. It probably will use about as much electricity as straight electric, but it, at least, probably won't itself switch to backup electric resistance heaters. Further down east, or anywhere in the interior... not so much. If you're only backup is straight resistance electric, you will have a dramatic electricity bill. If, however, you are fortunate enough to have a backup LP or oil fired source, I'd agree with @pecmsg -- somewhere around 20 F or so you'll want to switch.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 15,612
    The outdoor coil will start to ice and frost when the air temp drops below 32 degrees but with air moving across the coil it's around 25 degrees before you get much serious coil blocking. Then the unit will start defrosting
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,881
    edited July 2021
    The dealer needs to be able to answer this. Google says this HP works down to -15F at a COP of about 2. Whether its output at that temperature (~10k BTU it looks like) is enough on its own will depend on your home. Past electricity/gas bills can help you figure out how well it's sized. It doesn't need to meet 100% of your heat loss to be economical, but it depends on your situation.
  • Ironman
    Ironman Member Posts: 7,379
    The part of the equation that’s not being discussed is the ACTUAL heat loss of your house vs. the output of the heat pump at any given temperature. Your locale factors into that, but a manual J load calc would need to be done to get an ACCURATE answer for your specific house.

    As stated, the type of backup heat and its operating costs is another major factor.

    There’s simply no “one size fits all”,  pat answer to your question.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.