SKYROCKETING electric bill after new HVAC install

Old 02-08-18, 11:21 AM
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SKYROCKETING electric bill after new HVAC install

Hi there. We recently had a 500 sq foot addition put on our house, bringing our total sq footage to 2,000. It's a 1 1/2 story home, the only thing upstairs is a small master bedroom with access to a walk (crouch)-in attic. The addition included a sunroom with a lot of windows.

During the construction, we upgraded our (1988) system to a new electric heat pump and AC unit.

The unit has 3 thermostat controls. One in the main hall, one in the opposite side of the house and one upstairs. The one upstairs is on a wall between bedroom and the attic. Three seemed excessive to us but apparently thatís what our County code requires. The thermostats are Aprilaire.

Our electric bills have gone from an average of $140 in the winter time to over $300.00. Before we even got our first bill, we noticed several things that didn't seem right:

At times, the thermostat reads up to 5 degrees warmer than the temperature setting. For example: Heat set to 64 degrees, but the thermometer reads 69 degrees.

The thermostat temperature reading can be different from the actual air temperature. We have not gone as far as buying thermometers but when the thermostat says it's 64 and you could be comfortable in a t-shirt and shorts, something is off

The Emergency Heat indicator goes on often even if it's not that cold out (like 40-50 degrees) We live in North Carolina.

Overall, the heat temperature settings are usually lower than it feels in the room.

We had our technician out once and said he made adjustments, but the problem continues. The strange thing is it's not all the time. I may get up 4 freezing mornings in a row to the temp set at 64 but the reading be 69, but the fifth day it will read correctly. (set at 64, temp at 65).

Also, when we wake up and turn the bedroom thermostat up, itíll run for a bit, and then shut off. Then itíll kick back on in 2 minutes.
Iím including some pics of air handler label, ac unit, feeds and a zoning panel (TrueZONEģ HZ322 Panel). Note the size of the new feeds that were run, double the size of the existing 7Ē. Is this excessive?

Does anyone have any idea why these issues may be happening, or suggestions to remedy?
Thank you!
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Old 02-08-18, 01:43 PM
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What are the other two zones t'stat readings for temp. and settings when you have the problems with the one zone? If you have an air source Heat pump, efficiency decreases with decreasing temperature. If it goes below freezing at night. I would think the control switches to supplemental heat. Is the electrical heaters the only source of supplement heat?
Old 02-08-18, 03:58 PM
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Based on the electric bill, this sounds like cold air is draining to the sunroom, which is unable to cope with the load, and flipping to emergency heat.

This also suggest that there's a problem with the circulation pattern,
i.e. hot air flows through the house and shuts down other heat zones, while cold air drains along the floor to the coldest room. The result is the coldest room is running constantly, using the least efficient heat, and the other zones are doing nothing.

Last edited by Hal_S; 02-08-18 at 04:29 PM.
Old 02-08-18, 04:46 PM
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What kind of heat did you have before you installed this new heat pump syhstem?

Is the house inherently drafty with frequent changing temperatures even if the heating system is shut off for a few hours?

Do you re-adjust the thermostats often?

Some heat pump systems will go into emergency heat if you move the thermostat setting up by more than (sometimes as little as) 3 degrees. The idea is to heat up the room faster.

If you leave the thermostats at the same setting all the time and cold air is not pouring in say from an open window, then the room temperature should not drop fast enough after the system cycles off to turn on the emergency heat when the system cycles on again.

Did the technician check the Freon level or pressure recently? Short cycling can mean you need a Freon recharge.
Old 02-08-18, 06:25 PM
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This is all upgraded to brand new equipment.

In order for emergency heat to be active.... the emergency heat and one of the other heat indicators needs to be on. I'm guessing your zone 1 stat has E heat on it.

With a Truezone system.... I believe the AUX heat is controlled by a timed function. In the programming it's called stage 2. That can be set longer to allow the heat pump to try to heat before the AUX electric is engaged.

The Truezone should have the ability to monitor outdoor temps and use that to control stage 2 (electric reheats).
As mentioned..... large night setbacks should be avoided.

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