Greetings all.

I recently moved into a new apartment in Phoenix, AZ that has a heat pump. This is my first time living with a heat pump, and I'm trying to figure out some things. First, I just received my first electric bill at this new place. It is triple what I normally pay for December in Phoenix. Obviously, its not cold here, but heat is needed throughout the nights as the temp does get into the 40s. I'm trying to track down the culprit of the triple electric bill, and my hunch is at this heat pump unit.

I'm pretty sure the unit runs consistently. I hear it turn on several times in an hour throughout the day, yet the heat (blower) is not actually running. Is this normal? Is the heat pump just warming up the coils in case heat is needed? This seems to be very inefficient if so.

Based on that last statement, it appears the heat pump unit outside runs independently of the blower unit inside? I'm assuming the blowing unit inside is the recipient of the heated coils from the outside unit to heat the air and then distribute it throughout the ducts. Is this true?

What is anyone's diagnosis of my electric bill and subsequent tie in the always hearing the heat pump on? Could the wiring from the heat pump to my thermostat be wrong? I completely turn off the thermostat, but I still hear the heat pump outside running right now.

Any help or guidance would be appreciated. I am pulling my hair out trying to figure this out. I'm trying to educate myself as much as possible before working with the complex maintenance guys because they seem to refuse to call in a heat pump repairman.

It doesn't sound like your heat pump is working correctly to me.

If you refer to the attached diagram, the basic heating mode operation is such:

1. Outside air is used to warm the refrigerant
2. The refrigerant releases its heat inside the house
3. The cooled refrigerant is returned outside to be rewarmed

The surprising thing is that you can actually get heat from the outside air when it is 40 degrees, but it does work. However, when the outside temperature drops too low, there is not enough heat to be had, so there is also an electric heating element in the inside unit to provide heat in this case. On your thermostat, there should be some lights labeled "Emergency Heat" or something similar. If these are on, it means the electric element is being used--which will boost your electric bill.

You also said the blower does not run. This sounds like a big problem (and may be the root problem). While the inside and outside blowers will act somewhat independently, they basically run at the same time.

Another problem you've noticed is that the outside unit runs regardless of whether your thermostat is on or not. This sure doesn't seem right.

Since this is an apartment, I'd definitely notify management and get it fixed. In addition to mentioning the sky-high electric bills, I'd tell them everything you've mentioned here and say that you think it could be damaging their equipment--costing them more money in the long run.

Best of luck,
WallyH

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Thanks for the information. The diagram was very useful for me to understand the system.

I did some more research today. The outside heat pump unit is indeed on throughout the day. I have verified this by comparing our electric meter when the unit is off, compared to when it is on, and the meter is indicating significant electrical usage during the day. It is 70 degrees out today, no heat/cooling is needed. I have the thermostat set to off, yet the heat pump unit continually runs throughout the day. What might be causing this?

I have pulled open the ceiling blower unit to see around inside there. When the exterior heat pump unit is on, there is a small copper wire/pipe that turns very hot to the touch during operation. When the exterior turns off, that same copper wire/pipe only becomes lukewarm. I am guessing these are the coils that actually heat the air when in operation, which makes sense, but does not make sense why it is warming throughout the day when the thermostat is completely off. Something is triggering the unit to start up and run.

The small tube you are feeling is one of the red lines in the drawing. It should be pretty warm to the touch.

There should be a relay in the outside unit that controls the compressor. If it is stuck in the "on" position, your compressor would run continuously. This is not a user-serviceable problem, and I would suggest contacting your building maintenance people or management to get it fixed.

Since you have 70 degree days (man, am I jealous), you could find the circuit-breaker for the outside unit and flip it off to save power while waiting on someone to really fix it.

Good luck!
WallyH

My heat pump is on A/C (cool mode) and Fan (auto) at 78 degrees. However, in the last 2 days, it's constantly running with the temp. rising to 82 degrees +/-. We had a HVAC man come and he said the refrigerant was very low - so he added 10 lbs. ($$) which seemed to do the trick - now we're having the same problem again. What do you think is the problem and the best way to solve?

We bought our home in 2003 and I believe this is the same unit since 1985 when the house was built.

Thanks!

LS