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Old 11-06-2012, 09:14 AM   #16
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Heat pump not working properly after hurricane power outage


Well, a friend's father who works in HVAC stopped out last night and we looked at the system together. He put his gauges on the high side / low side and even though we didn't have the pressure standard, he said the pressures he saw didn't look like anything to be concerned about. After running for 10 minutes, the closest duct temperature was about 85 degrees. Using my energy meter, I can see that the heat strips are running almost every time the heat pump cycles on, and it isn't even waiting for a long delay. I also saw them running consistently on a 50 degree day, which I know is not good. Last night, we unplugged the heat strips and let the system run by itself. My power usage shows that the system came on at 1am and has been running since with the thermostat set at 70 degrees. Granted, it was a colder night last night, but it shouldn't have had to run nonstop to maintain that.

The outside unit is a Carrier 38YZA036 (3-ton) and the Air Handler is a FV4B. The paperwork I have shows it to be a 14 SEER system.

I've attached a picture to show the power usage (collected from my TED5000 unit). All the spikes above 15kW are the heat strips kicking in. Around 1am, you see the heat pump come on and not stop. In fact it is still running as I write this. I went out and looked at the outside coil and there is a very, very thin layer of frost on the coils in a horizontal pattern.

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Old 11-06-2012, 03:42 PM   #17
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Heat pump not working properly after hurricane power outage


One thing that hasn't been mentioned (or I didn't see it) is that heat pumps will freeze up in cold weather and for that reason the reversing valve changes the direction of the refrigerant to thaw the outdoor coils. Unfortunately when this happens you are running AC in the middle of the heating season. It's also necessary. However when the defrost cycle kicks in it stops the outdoor fan and turns on the strip heat to overcome the cooling cycle. I imagine you could override the heat strips so they didnt come on when the unit defrosts but then you would be pumping cold air into a space you are trying to heat. Seems a bit counter productive to me. Your graph shows just how efficient a heat pump is.
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Old 11-06-2012, 04:16 PM   #18
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Heat pump not working properly after hurricane power outage


So on a 40-50 degree day, it is normal for the strips to come on that frequently? From what I have read, the newer heat pumps, especially a 14 SEER unit, should be able to run without heat strips down to 30F or possibly lower.
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Old 11-06-2012, 05:10 PM   #19
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Heat pump not working properly after hurricane power outage


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So on a 40-50 degree day, it is normal for the strips to come on that frequently? From what I have read, the newer heat pumps, especially a 14 SEER unit, should be able to run without heat strips down to 30F or possibly lower.

No. It's an adjustment that can be made to prevent it from happening. It's a tricky thing though, it must be there when needed. Often it's set a bit higher....but it's definately not needed at 50 deg. And depending on the thermostat controlling it it may be difficult to dial it in.
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Old 11-06-2012, 05:29 PM   #20
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Heat pump not working properly after hurricane power outage


Last night your area dropped to 25 according to wunderground. So it should have had to run for hours on end to maintain temp. What thermostat do you have?
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Old 11-06-2012, 05:45 PM   #21
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Heat pump not working properly after hurricane power outage


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Last night your area dropped to 25 according to wunderground. So it should have had to run for hours on end to maintain temp. What thermostat do you have?
The Carrier non-programmable.
Looks like this:


Yes, it did get cold last night so I would have expected it to run that long, but tonight will be 32, so I am curious to see what it does.

Are those settings that you mention the ones controlled by the jumpers on the back of the circuit board or is it the thermostat that calls for the Aux. heat?
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Old 11-06-2012, 06:07 PM   #22
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Heat pump not working properly after hurricane power outage


Thermostat calls for aux heat.

Can't tell the model number of the stat by a pic. Some of them have the ability to do a time up to bring on the aux heat. Doesn't matter what the outdoor temp is.
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Old 11-06-2012, 07:07 PM   #23
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Heat pump not working properly after hurricane power outage


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thermostat calls for aux heat.

Can't tell the model number of the stat by a pic. Some of them have the ability to do a time up to bring on the aux heat. Doesn't matter what the outdoor temp is.
tstatccnhp01-b
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Old 11-06-2012, 07:21 PM   #24
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Heat pump not working properly after hurricane power outage


That one doesn't have the time up feature. At least not in the install manual online.

I think I'd get a different thermostat anyway.
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Old 11-06-2012, 07:56 PM   #25
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Heat pump not working properly after hurricane power outage


Got a recommendation?
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Old 11-06-2012, 09:21 PM   #26
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Heat pump not working properly after hurricane power outage


Honeywell. A higher end model.
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Old 11-06-2012, 09:21 PM   #27
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Heat pump not working properly after hurricane power outage


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