2014 Lennox heat pump puts out 81 degrees for about an hour

and then warmed up to 123 degrees as measured at the registers.

I was about to report it as a defect…but then just happened to recheck towards the end of the inspection

but literally for over an hour it was blowing at 80 degrees

ambient temps were around 45 degrees outside

This is not something I’ve experienced before. The unit appeared to be well cared for, the evap coils and coils at the compressor were clean as were all filters.

Try turning OFF the emergency heat.


I never did turn on the emergency heat.

When I got there the heat was already on…set to 60

I bumped it to 64 and nothing else…

then measured at the registers.

without emergency heat…just normal heat…I always get over 95 degrees at the registers.

just not sure if I should call this out or not…

Not uncommon for straight heat pump settings. Usually the backup heat strips provide the most heat output when activated and even if they are installed. The highest temp I ever got from a straight heat pump was 92 degrees.


What was the room temperature when the heat cut off?

wouldnt it notify you on the thermostat if the heat strips kick in?

I would expect it would…but that doesnt seem to be the case.

and after about an hour it was reading over 120

which is what I commonly see.

but on the thermostat it was still saying “heat”

not “emergency heat”

if that makes sense?

I dunno, have a photo of the thermostat when you got your high temp?

no, and I wont be going back to that house

have another inspection tomorrow.

hopefully it will have a digital thermostat and I can get pics


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new property today

goodman heat pump 2016

walked in and it was set at 67

outside ambient was around 55

turned it up to 70 and went and measured the temps at over 100 degrees. No indication of emergency heat being turned on.

I then turned it up to 75 and “auxiliary heat” came on at the thermostat.

temps went up to over 120

this is what I find pretty much everyday.

So this is why I was concerned when I was seeing 80 degree temps at the house yesterday

does this make sense?


Is this an all electric HP?

You can do an amp draw when the heat strips kick in if you want to confirm they’re functional.

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Measuring the temperature of air at the registers is always deceptive. The goal is to bring the ROOM temperature up to the thermostat setting. Register air quickly dissipates and cools as it mixes with cooler air in the room. A Home Inspector needs to check that each habitable room has a heat source and that it operates (supplies warm air). Any attempt to measure the temperature or efficiency of the heating or cooling will be misleading, time consuming and way beyond the standards.


At 80 degrees, I would call it out.


Call it out. You have an airflow problem.

I see that filter crap inside the registers. Not helping. A furnace is not an air cleaner. They probibly have high density return filters as well.

Let the HVAC guy yell at them…


thanks guys

I did call it out in the report already

I was worried that I had misdiagnosed and called out something that shouldnt have been.

but guess I knew there was an issue as I do that temp test every day , and this one was low

thanks for all the help!

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that makes sense.

perhaps I should stop measuring temps at registers


I guess I knew the heat strips were functional as once the emergency heat kicked in the temps jumped to over 120 degrees.

my concern had been that under normal heating it was only getting to 80 degrees…and was putting that out for over an hour. Then it went to the heat strips.

The newer units/thermostats are somewhat tricky to bypass the unit’s brains that are programed for most energy efficient operation. From talking to some HVAC guys you may not be able to get the Heat Strips (or gas heat) to come on using “Normal Controls”* if the outside temp is above a certain temperature (something like 45-50). You may need to really know what you are doing to bypass the normal operation of the Thermostat for Aux-heat/heat strips to kick on (same with some those that use Gas for Aux heat mode. I just really shy away from trying to bypass anything which could screw up the programming. (Kind of like trying to check sprinkler timers, so many different ones out there)

(* we should probably not be bypassing and going into an expert or Diagnostic mode at the thermostat)

I love the old double bulb mercury thermostats where you can easily see when it is operating in Heat-Pump versus Aux- Heat mode.


Why are you listed as a non-member?

It was my understanding that setting a heatpump >2 degrees higher than the ambient temp automatically kicks on the auxiliary heat to accommodate. Is that true?

This is my understanding, when there is an auxiliary (or emergency) heat setting on the thermostat, you must manually switch it over from heat-pump to auxiliary heat. This is because a heat-pump will be unable to produce effective heat on a really cold day (around 20 f or less?). And, not every heat-pump has auxiliary heat. This is often (in warmer climates) an added accessory.

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