Aux Heat with Heat Pumps

17 years ago

I have a heat pump in my house. I guess it's supposed to be high effiency because it works great. We have this cold wave happening right now with single digit temps, and I was wondering about the "emergency" heat. I tried it out one cold day and no hot air was coming out. I'm guessing that I didn't have any of those heating elements installed in my heat exchanger. Is this common? Anyway, the whole thing was replaced in 2003 and I know who did it, so I'm going to give them a call and ask as soon as the mega-cold weather is over. I'm sure they have enough going on without me pestering them. Also, anybody know how much extra $$ it is to have those installed for an "emergency"? Thanks a bunch!

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Comments (13)

fsq4cw
17 years ago
Is the separate breaker for 'Aux Heat' switched 'ON'? Do these elements not come on automatically? Is there an indication on your thermostat when 'back-up' 'Aux' heat is demanded?

I'd imagine your home would be pretty cold without it operating correctly.

SR
bob_brown
17 years ago
Hello,
Typically a system has aux heat when using a Heat pump. It can be fuel and the HP of electric and the HP. If a salesman went for lowest bid, I can see installing a air moving only Air Handler. This is not normal. You could have a problem with the controls to the electric heat, or possibly a bad stat. If you turn on the hard switch for aux heat and nothing happens, no light or anything then it is wrong. This switch bypasses the automatic control. Some system use a PCB to control the strips, and this can be bad.
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garyg
17 years ago
If you didn't have electric resistance strips installed for auxiliary heat, your house in Ohio would be mighty cold with single digit temperatures outside. At temps below 30 degrees F, the typical air-source heat pump cannot alone supply the heating requirements and auxiliary heat is needed.

You can check if your aux heat is working by bumping up the thermostat setpoint by more than 2 degrees, which should trigger the aux heat to kick in. If you have a digital thermostat, there should be some kind of aux heat display on the thermostat. Next, check the air temperature coming out of a vent close to the air handler. If the electric strips are energized, the air will feel warm to your hand (the air temperature with strips is >110 degrees and your hand is 90 degrees). If the air feels kind of cool (heat pump air is about 87 degrees or so), the strips are not working.

My heat pump has 2 electric strips. One is energized when auxiliary heat is on, both are energized when emergency heat is on.

My guess is that your aux heat is working but your emergency heat is not working. Maybe incorrectly wired to the thermostat.
clg7067
Original Author
17 years ago
The previous owner worked in finance, so I could see him cheaping out on the system. (Not that I'm generalizing. ;) ) The thermostat has the extra position for the Emergency heat, when I slide it there the icon changes, but no hot air and the temperature in the house decreases. Like I said, I'm going to have them check it out when it warms up, but just wondering.
clg7067
Original Author
17 years ago
garyg, that's interesting. And I thought it was my nice little heat pump doing all the work. The air always feel cool to me, but I'll try that and see if it warms it up.
tigerdunes
17 years ago
clg

It is difficult for me to believe that you do not have aux strip heat in your HP air handler considering the wicked cold weather our country has at the moment. Is your inside thermostat temp setting being maintained? If so then I would expect you have a connection issue with the emerg heat setting.

Post back and let us know what your installing dealer finds.

Good LucK!
dadoes
17 years ago
Everybody who has responded to this thread seems to be overlooking the fact that a heat pump *must* have auxiliary installed and working, or the system will blow COLD air into the house during defrost. If the OP is NOT having cold air blow inside during defrost cycles, then there ARE auxiliary elements installed.

If they don't run when the thermostat is set to EMERGENCY HEAT, then there's a wiring problem or some other problem.
clg7067
Original Author
17 years ago
garyg, I tried to you suggested last night, raising the thermostat by 2 degrees, and hot air did, indeed, come out of the register. I feel much better now that I know how this stuff works. Thanks.
garyg
17 years ago
Good job, clg.

You still need to get your "emergency heat" function checked out. You need this in case your heat pump (outside unit) dies in the winter. Emergency heat is expensive (electric resistance) but it's great to have that back-up.

As TigerDunes stated: "Post back and let us know what your installing dealer finds".
zzxx
17 years ago
"Some system use a PCB to control the strips, and this can be bad." What does PCB stand for?
User
17 years ago
PCB is Printed Circuit Board

HTH
Chris
ckmb5150
17 years ago
alot of thermostats require the installer to put a jumper wire between the "E" (emergency heat) terminals and the "W2" (2nd stage heat) terminals on the thermostat's subbase.
its a common mistake that i see on alot of systems and it sounds to me like its your problem....

heat pump and second stage heat works but no stand-alone Emergency heat?
yep,if i were running this call that would be the first place id look.
using emergency heat wont give you more heat but it will be your best friend if your heat pump dies .
hope this helps
clg7067
Original Author
17 years ago
Yes, that's why I was checking it out, in case the heat pump dies. I'll print this out and save it for the service call.

Aux Heat with Heat Pumps

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Aux Heat with Heat Pumps

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