Heat does not seem to be working correctly


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Old 02-15-16, 02:02 PM
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Heat does not seem to be working correctly

I've noticed that it seems to take an incredibly long time for my heat pump to heat up the house. My house is about 1700sq ft that includes the finished basement. My house is laid out weird and the kitchen, living room, main entrance, hvac/water heater room, full bathroom, laundry and office are all in the basement. The floor whole basement has a tile floor. My house is older built in the late 70's but it seems to be insulated very well. To the point of spray foam insulation in the attic which technically makes it a conditioned space. I have a split armstrong unit. The hp model number is 4SHP18LT and the air handler model number is an Armstrong EFV16CCP-1A. I also have a Nest thermostat. My unit seems to take forever to heat up the house.

For example. I was out of town on Saturday night. I came home and the temperature in the house was 58. For reference the outside temp was 25. I set the thermostat on 67 at 11:18. The unit came on an at 12:30 it was only 60 in the house. at 2:34 it had warmed the house up to 63. To me something does not seem right. I have a 7.5kw heat strip. I believe it was on while this was going on. Does this seem right?

I'm going to do the same thing tonight when I get home from work and see what happens. I will also verify that the heat strip is coming on. I also have solar panels on the roof and CT's installed in the breaker box that has a display showing how much load the house is pulling at any given moment. It's very easy to tell when the heat strips kick on.
 
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Old 02-15-16, 04:46 PM
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Welcome to the forums.

I set the thermostat on 67 at 11:18. The unit came on an at 12:30
That sounds like a problem right there.

With a heat pump...... slow and steady is the key. A heat pump should be allowed to run almost continuously so that the electric heat coils don't come on. A setback to 53° is way too low. When the inside air is more than 3° or 4° below the setpoint.... the electric coils come on.

With a heat pump I don't recommend a setback at all.... although a few degrees should be ok.
 
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Old 02-15-16, 07:19 PM
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I understand what you are saying but I knew I was going to be gone for 24 hours so I set the tstat to away temp which I have set at 60. Is this to much of a set back?
 
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Old 02-15-16, 09:02 PM
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As a one time thing it's fine. It just costs a lot of money to recover from the much of a setback. The heat pump as well as the heating coils should have been running to heat the house.
 
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Old 02-16-16, 05:57 AM
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The modest heating that you are experiencing could be the 7.5kw heater alone - with nothing from the heat pump - or vice versa ... with 25F, I'd hope that both would activate for the temperatures you mention.

Does the larger refrigerant line from the outdoor unit get hot to the touch ? Does Emergency heat (alone) work ?

Or, considering that the supplemental heat is only 7.5kw, perhaps the system was not designed for 25F ambient ?
 
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Old 02-16-16, 06:08 AM
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Yes the large line from the outside unit does get warm. I wouldn't say that it gets hot though.

Here are links to the manuals for the heat pump and air handler.

http://www.armstrongair.com/_/pdfs/i..._44876d006.pdf

http://www.armstrongair.com/_/pdfs/i..._506257-01.pdf


So I did some monitoring last night and these are the results.

I have an outdoor wireless thermometer that I sat on top of the a coil to get the temperatures mentioned below.

The outside Temp was 33.

Temperature inside the house at 6:22 was 61. I set the thermostat to 67 and Stage 2 Heat came on. I verified this on the air handler board as the LEDS for G, Y1, and Y2 lights were all on. The fan speed was around 1000cfm calculated by counting the pulsing LED on the board. The temperature difference between the inside air and directly above the a coil was ~7 degrees. The house was pulling a total of 1.9 kW. This included a couple of compact flourescent lights, the tv, and a small humidifier in my bedroom.

At 6:43 the fan speed increased significantly to approx 1600 cfm calculated by counting the pulses again. House load went up to 9.7 kW. I'm assuming the hp went into defrost mode. The G, Y1, Y2, O, W1 and E LED's on the air handler were on. Also I reinstalled the air handler cover after every check of the LED lights. The A coil temp slowly dropped to from around 68-69 to 55 degrees.

At 6:52 the house load dropped to ~2.4 kW and the air speed decreased back to roughly 1000cfm. The inside temperature had dropped from 61 to 60. The a coil temp started increasing and was at ~70 degrees at 7:01.

7:14 same conditions as above. It was still 60 in the house.

At 7:34 the fan speed increased again to ~1600 cfm. This time the strip heat came on and house load jumped to ~10kW. I checked the Air Handler LED's and G, Y1, Y2, W1, and E were all on. This I believe means that it was not in defrost mode but actually using strip heat.

At 7:42 the same running conditions exist as above. The a coil temp has increased to 67.1 but the inside temp is still 60 degrees.

At 8:08 the same running condition exist as above. The inside temperature has increased to 61 degrees.

I stopped monitoring it at this point. Does this seem like it is operating correctly?

I've added some pics of the wiring. I'm wondering why the black and white wire at the air handler are tied together.


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Last edited by hlewis12; 02-16-16 at 06:31 AM.
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Old 02-18-16, 07:01 AM
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I stuck a thermometer inside pipe insulation of the large line from the outside unit at the temperature it gave me was between 115 and 120. Does this seem right?
 
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Old 02-18-16, 08:26 AM
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The large refrigerant line from the condensor should be too hot to touch.

You should be getting a heat gain of 15°-20° thru the heating coil.

It sounds like your heat pump is not performing up to par and needs to be checked. Could be a possible refrigerant issue.
 
 

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