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The temperature outside is about 20° my thermostat is set to 68° I have a heat pump unit it does not turn off once the set temperature is reached it does not go above 68° but maintain 68° and the unit keeps running the question is how do I prevent this from happening right now the heat is turned off And the temperature is staying at 68° please help?

MR C
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    If you set the thermostat to 65 does the unit turn off? It's possible that 68 is right at the maximum temperature that your unit can produce given the outside temperature and the thermal load of the home. – jwh20 Jan 20 '20 at 16:03
  • There are outside air temperature switches that prevent the compressor from running when it is too cold. Of course then you have to rely on emergency/aux heat. – JPhi1618 Jan 20 '20 at 16:10
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    OK I set the temperature to 65° turn the unit back on remember it’s sitting at 68° now it momentarily ran then it turned off it will be interesting to see that when the temperature goes down to 65° will it continue running again I’m not sure but thank you for the advice I will get back to you – MR C Jan 20 '20 at 16:17
  • Try turning the system off at the thermostat, or like jwh20 suggested, lower the setpoint several degrees and it should shut off, if not, you've got a problem in the outdoor unit. I have found that thermostats "lie" a bit when it comes to indoor temp. I've noticed if setpoint is 68 and indoor temp shows 68 and I reduce the setpoint to 66, within a few minutes the indoor temp drops to 67. I have in floor hydronic with a LOT of thermal mass, so there's no way the temp actually dropped that much. So like jwh said, your system is barely able to keep up so it runs all the time. – George Anderson Jan 20 '20 at 16:18
  • What make and model is your heat pump outdoor unit? – ThreePhaseEel Jan 21 '20 at 00:17
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    @GeorgeAnderson -- if the OPs system is modulating/variable speed, it could be throttling back instead of cycling... – ThreePhaseEel Jan 21 '20 at 00:18
  • That's a great call. I know mini-split systems do that, but didn't remember that more typical HPs can also do that. We should also ask if he has a traditional heat pump or a mini-split system. – George Anderson Jan 21 '20 at 02:06
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    It’s a YORK unit mod.#YHJR36S41S4A – MR C Jan 22 '20 at 13:47

1 Answers1

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Depending on the exact details of your heat pump, it may be functioning exactly as designed.

Modern efficient heat pumps are commonly variable speed (may say "inverter drive" or something like that), so that the compressor speed can be matched to the load

  • more load, more speed, more power
  • less load, less speed, less power.

So, rather than overshooting and turning off until the temperature falls, they simply slow down to match the output to the load and keep running, maintaining the temperature as set.

An additional factor with cold climate air-air heat pumps in cold weather is that they occasionally need to defrost the outside coils.

Ecnerwal
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