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Old 12-24-2008, 06:48 PM   #1
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Heat Pump + Aux Heat Problem - Can You Help?


Hello. I have a relatively new house (2.5 years) that has an American Standard Heat Pump (2a6b3018-060a1000a). It also has some form of American Standard aux heater (bayhtr???) in the air handler. This is controlled by a Panasonic TH8000 thermostat.

We have had a long period of cold weather here in Seattle and I have noticed that during this time two unusual behaviors are happening with my heating system:

(a) I have not see the AUX Heat indicator come on on the TH8000 thermostat. I have seen this frequently before and I took it to mean that the aux heater was helping the heat pump along. But I have not seen it at all in at least a week and I have looked frequently at the thermostat.

(b) There are times when the heat pump is not operating (I can see the fan blades stopped) but there is significant cool air (not icy cold but certainly not warm) coming out of my heating ducts. It is clearly being blown by a circulating fan in the system but there is no warmth.

I have looked as much as I can at the heating unit under the house and see nothing unusual. I checked the electronic air filter and it seems fine.

Any idea what may be wrong here? Thanks.

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Old 12-25-2008, 06:24 AM   #2
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Heat Pump + Aux Heat Problem - Can You Help?


May have a bad aux heater.

Need a multimeter to check it.

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Old 12-25-2008, 09:37 AM   #3
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Heat Pump + Aux Heat Problem - Can You Help?


Quote:
Originally Posted by beenthere View Post
May have a bad aux heater.

Need a multimeter to check it.
Thanks for the response. Here is some additional info. I tried placing the system on emergency heat mode and raised the thermostat a few degrees. After a few minutes, I started getting warm air out the the registers. I also noted that the aux heat indicator on the thermostat was showing. So I think this indicates that the aux heater is capable of working and the thermostat is capable of displaying when it is, in fact, turned on. What seems to be the issue is that something in the control system is not turning it on when needed. I am not sure if it is needed in other than the heat pump's defrost cycle. But I have been told that the occasional blasts of cold air I am feeling may be due to the heat pump's defrost cycle.
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Old 12-25-2008, 10:04 AM   #4
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Heat Pump + Aux Heat Problem - Can You Help?


Your aor handler may have more then one bank of strip heaters.
Its possible that one back is not working.
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Old 12-25-2008, 10:29 AM   #5
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Heat Pump + Aux Heat Problem - Can You Help?


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Originally Posted by beenthere View Post
Your aor handler may have more then one bank of strip heaters.
Its possible that one back is not working.
Thanks once again for your response. I found some info on the internet here http://en.allexperts.com/q/Heating-Air-Conditioning-696/2008/2/Heat-pump-thermostat-control.htm
and here http://en.allexperts.com/q/Heating-A...at-control.htm
that made me start checking things more carefully.

When this cold spell hit, I raised the temperatures on my thermostat schedules. I have never done this before. Under the previous schedule, I had simply raised the temp manually on the thermostat to what I wanted when needed. Thinking back, this is when I typically saw the aux heat indicator show on the thermostat.

So I just manually raised the temperature from its current setting by a couple degrees and indeed the thermostat does show the aux heat indicator. For this reason, I am thinking that the aux heater does, in fact, work.

However, I am not sure about if it is working during the defrost cycle of the heat pump. I only found out recently that there was such a thing. I may never have noticed it before because it has never been this cold this long since I have been in this house with the heat pump. Maybe the heat pump only has to go through a defrost cycle when it is very cold. Or maybe it does it frequently but I have only noticed it now because the air being used right now is so very cold.

Do I have to call in a pro to see it the thing is properly set/wired so that the aux heat comes on during the defrost cycle? Or is there some way I can check that?

Thanks and happy holidays to all!
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Old 12-25-2008, 10:48 AM   #6
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Heat Pump + Aux Heat Problem - Can You Help?


If you have a thermostat with Adaptive Recovery, it will atempt to recover without using the strip heaters.

You can always remove the air handlers panel, and see it there is a wire from the outdoor unit connected to W1 or W2 of the air handler, and connected to teh outdoor unit.

If there isn't, then its wired not to use aux heat during defrost.
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Old 12-25-2008, 10:57 AM   #7
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Quote:
Originally Posted by beenthere View Post
If you have a thermostat with Adaptive Recovery, it will atempt to recover without using the strip heaters.

You can always remove the air handlers panel, and see it there is a wire from the outdoor unit connected to W1 or W2 of the air handler, and connected to teh outdoor unit.

If there isn't, then its wired not to use aux heat during defrost.
My thermostat is a Honeywell TH8000. It does have an adaptive recovery mode. I saw it shown after I changed the settings. I had to look it up in the manual to see what it was.

So this may be all it is? The manual says it can take about a week for the system to adjust. But does this recovery mode only kick-in around the time(s) that the schedule changes? It seems like that is the only time I see the recover indicator shown on the thermostat. I feel the cold blasts at times other than when the schedule changes and I see the recovery indicator on the thermostat.

I feel that with your help I am starting to focus in on the problem and actually understand a little more of how my system works. Thanks again for all your time and help. Happy holidays.
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Old 12-25-2008, 11:27 AM   #8
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Heat Pump + Aux Heat Problem - Can You Help?


Adaptive Recovery is only when the stat is in recovery mode.

When maintaining set temp, it has no fuction.
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Old 12-25-2008, 11:55 AM   #9
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Heat Pump + Aux Heat Problem - Can You Help?


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Originally Posted by beenthere View Post
Adaptive Recovery is only when the stat is in recovery mode.

When maintaining set temp, it has no fuction.
So the recovery mode should NOT affect the use of aux heat during defrost?

It is possible that the unit is not set/wired for aux heat during defrost and that we just never noticed it before because the air being circulated was not this cold before.

Thanks.
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Old 12-25-2008, 12:04 PM   #10
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Heat Pump + Aux Heat Problem - Can You Help?


Manually raising the thermostat even a couple of degrees can and will cause the aux heat strips to activate. Using the internal program of the thermostat usually won't do this.


  • The "cool" air you are feeling is normal for a heat pump
  • When the aux heaters are on, you are spending a lot more $$$ on heating costs. The air may feel warmer, but you are paying for this luxury.
  • Colder outside air can cause the unit to operate for longer periods of time, and during those periods you can feel that cooler air coming from your vents
  • Colder outside air can also require the unit to defrost itself more often, as frost buildup can easily occur with such units. An example:
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Old 12-25-2008, 12:10 PM   #11
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Heat Pump + Aux Heat Problem - Can You Help?


Thanks for that response and the photo. I just wonder if my heat pump was wired such that the aux heater is not triggered by the defrost cycle?

I also read that there may be a setting in the TH8000 thermostat which prevent the aux heater from being triggered if the temp is within some range. I am not sure if this is indoor or outdoor temp and if my thermostat is set that way. The owner's manual mentions it but does not say how to set/check this.


Cheers!
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Old 12-25-2008, 12:15 PM   #12
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Heat Pump + Aux Heat Problem - Can You Help?


Do you have the thermostat on circulate mode? This will just blow air around to help even out the temperatures throughout the house.
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Old 12-25-2008, 12:24 PM   #13
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Heat Pump + Aux Heat Problem - Can You Help?


The TH8000 series, can't prevent aux heat during defrost.

Your system may not be wired to use the aux heat during defrost.

Some contractors do that, to help save money during the heating season.
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Old 12-25-2008, 12:36 PM   #14
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Do you have the thermostat on circulate mode? This will just blow air around to help even out the temperatures throughout the house.
Thanks. I do not think it is on circ mode. The fan is set to auto and there are definitely times when I feel nothing coming from the registers.
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Old 12-25-2008, 12:49 PM   #15
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Heat Pump + Aux Heat Problem - Can You Help?


If you have any of the events, (wake, leave, etc) programed for circ, it will over ride the fan auto setting on the screen.

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