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Heat pump in heat cycle

my son has a Lennox 14HPX-036 heat pump, with no auxilliary electric or other heat, at a vacation house that he is having trouble getting heat out of. I believe this unit is 36,000 btu/hr rating and has a 36,000 btu/hr air handler attached. Having trouble getting any heat out of it at all, in 40 degree outdoor air temps, cannot keep 1,300 s.f. house above 53 degrees inside with outside temps in the 40's.

The one HVAC company who looked at it is having trouble diagnosing the problem. Last week they said the equalizer tube in the outdoor unit had broken and they replaced it and added 9 lbs of refrigerant. Within the same day, the unit could not deliver warm air and in the one visit since they have not gotten back to us with the problem or a repair solution.

Anyone have any thoughts/suggestions?

And, we'd be interested to know if an auxilliary natural gas furnace could be added to the air handler for heat at low outside temps. Lennox says their Merit funaces work with this unit and run the heat pump at higher outdoor temps and the furnace when the outdoor temps are lower to minimize cost. Anyone have any experience with these units?

Location is in Long Beach Island, NJ (basically southern NJ). Thanks in advance.


  • John Mills_5
    John Mills_5 Member Posts: 935
    You would have to replace the air handler with a gas furnace to have gas backup. Adding strip heat to the air handler lots easier if his electric panel is big enough. In a cold climate, should never have a a heat pump without some kind of backup to keep the joint above freezing in a heat pump failure. Like now.

    Shouldn't be this complicated. Tubes rubbing together does happen, hard to say why after fixing and recharging it is not heating again.
  • Gary Smith
    Gary Smith Member Posts: 363
    Thanks, I'm having someone else come by to look at it. It may have been designed as only a summer occupied house at the shore, unfortunately the previous owner didn't leave us any information. Lots of houses at this location are not occupied in the winter and are left to go cold after draining all the plumbing and putting antifreeze in the traps.

    But still, I would think a 36,000 btuh unit would provide a little more than 4 degrees differential, right now tstat is set for 72, outdoor temp is 58, indoor temp is 62 and the wifi tsat says the heat is on and fan running.

    Trying to puzzle out a new to us system.
    JUGHNE Member Posts: 8,317
    edited November 2017
    So simply you had a leak and lost all the charge.
    Leak repaired and recharged.

    So unit could have gotten air in system.
    Proper repair practices should have corrected all this.

    How "fast" were they in getting done?

    The "repair" techniques could have been lacking if they were in a hurry. Heat pumps are very sensitive to any foreign matter in the system. Some very small moving parts inside.

    The bill should include dry nitrogen gas, a filter drier and of course refrigerant.
  • Gary Smith
    Gary Smith Member Posts: 363
    Thanks no filter drier on first crack at it, was told tonight it needed a new trx valve and filter drier, that thes had become clogged and were causing high pressure shutdown. Sounds possible as unit has never been serviced and former owner only wanted the least cost unit installed to sell the house. Will know more tomorrow noon after those parts are installed.
    And thanks for your response. Is your forum name pronounced June? My dads nickname was june
    JUGHNE Member Posts: 8,317
    Jug was childhood nickname.....H was accidently added..........NE is Nebraska, where I am located.
  • Gary Smith
    Gary Smith Member Posts: 363
    Oh, see lots of your posts, never knew how to say it in my head.
  • unclejohn
    unclejohn Member Posts: 1,718
    That unit should heat the house at that outdoor temp. to at least 75* or more. I'm in Del. rehoboth beach with a two ton heat pump and have not used elec. back up heat at all since last Tuesday. Tstat at 72. Nice and toasty. Have the co. pull at least a 500 micro vac and you should be okay.
  • Gary Smith
    Gary Smith Member Posts: 363
    Thanks @unclejohn, repair co. replaced a valve and drier in the unit and it has been working terrifically since. 72 deg inside with 30-31 deg outside over the Thanksgiving weekend. I don't know how low an outside temp it will heat to, but I guess we'll see. The house was built as a summer use only vacation house with no supplemental electric resistance backup heat. We're hoping it will keep the inside to 38-40 on the coldest nights.
  • mikeg2015
    mikeg2015 Member Posts: 1,178
    It should manage that. The heat pump will lose capacity as it gets colder outside, but then gain some as it gets cooler indoors.
    SO figure at 10F you'd be down to about 70% capacity at 10F, indoor temp of 50-55F.

    Keep in mind that even on cold days, it's warmer 8-10 hours of the day and it will get ahead a little.

  • unclejohn
    unclejohn Member Posts: 1,718
    Gary if you plan on keeping the house open all winter you should at least shut off the water and turn off the water heater. If you get a heavy snow that ices over the heat pump all bets are off. Plus insurance won't cover water damage from broken pipes in unoccupied house.
  • Gary Smith
    Gary Smith Member Posts: 363
    Thanks, good advice, much appreciated.
  • BobC
    BobC Member Posts: 5,190
    If you can, build a shed roof over the outside unit which hopefully in the lee of the house against winter storms. Go 12-18" proud on that shed roof to shield the heat pump from snow.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Gary Smith
    Gary Smith Member Posts: 363
    Ok, thanks, makes sense.
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