Heat Pump and power consumption

[Old Red]

Our last month's bill here in central Va is the highest since we've lived here in 17 years. This is with a 3 kw solar panel system that saves us about $50/month. We've 3 heat pump systems. Only one (the biggest) do we allow the heat coils to kick in because it will not keep our family room warm enough with some heat coil assist. We've the upstairs heat pump's heat coils locked out via the thermostat because it is on our generator and would overload it. The basement ductless units do not have a heat coil backup and are the most efficient system we have. All are fairly new.

Ralph

How much was your bill? I am hearing this all over here in KY. Everyone is talking bout how high their electric bills was....basically everyone has exact same story as you......"just received my highest bill in 5 years...20 years" etc. I am still waiting on mine. Father in law's was $700 but his house in a monster and not insulated well.

Mine was $251 and I heat and cool around 5,500 SQ Ft. But the meter read date was 12/27 and I think that is right before the cold snap.

 

[dragoneggs]

This thread has got me more curious about my electric Trade furnace/heat pump setup along with an inline Honeywell Electronic Air Cleaner. Checked my breakers... both the furnace and heat pump are 50amp. I pulled the electronic filter and prefilter and washed them with detergent and rinsed are blowing them out with air. They should have been a lot dirtier since I cannot remember the last time they were cleaned! :ashamed: Letting them dry now. I'm hoping this will improve the flow and efficiency as well.

 

[ultrarunner]

The sequencer stuck on my heat strips last night. I had the thermostat set on auto and noticed the house felt too warm. Turns out the heat strips were running and the unit had switched to AC mode to try and maintain temp. It was holding at 75 where I had the AC set but it had to be eating some amps. I turned off the heat strip breaker and let it run a few minutes to cool off then shut the whole system down and opened some doors. Weather warmed up to the point I had to turn the AC back on. Unit will work fine with the heat strip breaker off for now. The sequencer clicked open when I pulled the wires to test it and it may work okay but I ordered a new piece anyways. Last time the sequencer failed it burned up my heat strips also but I caught it in time to save them this time.

I wish I could find a thermostat that would allow one setting for heat and AC but they all have a 3 to 5 degree spread. If you put it on auto and set the heat to 70 the AC won't come on till it's 73-75.

I have an old two mercury bulb thermostat and it will allow mechanical changes to the point of overlap where both are running... super simple and requires no power or battery... bet it will outlast me.

 

[RickB]

We just moved to N.C. in September and have zero prior experience with heat pumps. This thread has been very helpful as I try to wrap my head around how this system works. Just got my monthly bill yesterday. 1700 sq ft of house built in 1992 with what may be the original system. $157 with an electric hot water heater to boot. I’m not too displeased for as cold as it has been.

 

[goeduck]

We just moved to N.C. in September and have zero prior experience with heat pumps. This thread has been very helpful as I try to wrap my head around how this system works. Just got my monthly bill yesterday. 1700 sq ft of house built in 1992 with what may be the original system. $157 with an electric hot water heater to boot. I’m not too displeased for as cold as it has been.

Wrapping my head around them as well. I’d like to clean my outdoor unit once the weather turns better. My indoor furnace is Trane and my outdoor unit is Bryant so it is not a matched set. Once I get it all cleaned up I think I will call a heating/air conditioning guy out to check all the refrigerant pressures, etc.

 

[goeduck]

When I checked again with the temp showing about 2deg less than the setting, the furnace was on but no heat pump.

The best I understand it at our temperatures now (30s, 40s) your outdoor unit (indicating heat pump operation) should be running anytime your indoor f��urnace is running. Unless it is just cycling down. Otherwise you are just running electric strip heat? Someone more knowledgeable may chime in.

 

[skipmarcy]

I've got a 12 SEER, 2.5 ton Goodman heat pump w/10k aux. strips that was installed in my new 1700 sf house 12 years ago. My unit works well as a heat pump down to around 18 - 19F degrees but does have to defrost quite a bit at that low of temps. My strips do not engage when in defrost, under normal operation. We set our t-stat at 74 the beginning of heating season and that is where it stays until a/c season. The only time my aux strips kick in are when the heat pump cannot keep the temp within 2 degrees of the set temp. and then the heat pump continues to operate while the strips are engaged until it gets the temp to the set temp. Then the strips will kick off and the heat pump will continue to see if it can maintain within 2 degrees of the set temp If it drops to 71 degrees, the strips will kick back on and the heat pump will continue to run/defrost until it hits 74 again. I use supplemental wood heat here too so the heat pump rarely engages the strips. Usually early a.m. when the fire has died down quite a bit and it's in the single digits outside.

 

[dragoneggs]

The best I understand it at our temperatures now (30s, 40s) your outdoor unit (indicating heat pump operation) should be running anytime your indoor f��urnace is running. Unless it is just cycling down. Otherwise you are just running electric strip heat? Someone more knowledgeable may chime in.

I'm still trying to understand my set up. It was installed shortly before we bought the place 10 years ago. I thought I had an electric furnace with aux heat pump that mainly provided A/C in the summer. A/C is something I have never had before living in the PNW. Now I see the heat pump is providing significant heat too. After doing some research on model numbers, I see my 'furnace' is really an 'air handler'. I have some more to learn.

 

[Sigarms]

Anyone who is running a gas furnace with LP gas and straight AC system would basically be pretty dumb not to invest in replace the indoor coil and outdoor unit with a heat pump / coil. Straight AC unit generally takes the same indoor coil from the manufacturer that their outdoor heat pump uses. You might spend a little more for the heat pump unit than an AC unit, but the fuel savings on LP gas is pretty good when you don't have to use your furnace for heating until you hit the teens for outdoor temps. I replaced my Lennox pulse furnace in the attic years ago (straight gas / AC system) and cut my LP bill by 35%. Replaced one more system in the basement with a straight heat pump and cut the bill by 60%. LP company always seems to be trying to make it up to me now with their varying LP rates.

The term "hybrid fuel" is what Carrier coined years ago for dual fuel systems (using heat pump with gas furnace back up for heat).

Needless to say per the first paragraph on savings, this applies when LP gas costs more than electric, which it does around here at least.

 

[Old Red]

Anyone who is running a gas furnace with LP gas and straight AC system would basically be pretty dumb not to invest in replace the indoor coil and outdoor unit with a heat pump / coil. Straight AC unit generally takes the same indoor coil from the manufacturer that their outdoor heat pump uses. You might spend a little more for the heat pump unit than an AC unit, but the fuel savings on LP gas is pretty good when you don't have to use your furnace for heating until you hit the teens for outdoor temps. I replaced my Lennox pulse furnace in the attic years ago (straight gas / AC system) and cut my LP bill by 35%. Replaced one more system in the basement with a straight heat pump and cut the bill by 60%. LP company always seems to be trying to make it up to me now with their varying LP rates.

The term "hybrid fuel" is what Carrier coined years ago for dual fuel systems (using heat pump with gas furnace back up for heat).

Needless to say per the first paragraph on savings, this applies when LP gas costs more than electric, which it does around here at least.

This is what I will be installing next. I have resistive aux heat along with heat pump and when it is time to replace my unit my aux heat will be converted LP and my primary heat pump....as you said....dual fuel. That setup really shines with LP systems. I had a dual fuel at my other house but it was natural gas and that was less expensive that running the heat pump.

 

[kcflhrc]

I have the Dual Fuel, heat pump with LP back up. For Kansas it seems to be a pretty good set up. We have cold snaps but this year longer than normal. I have my heat pump locked out at 30 degrees, which means I run on LP under 30 degrees. I may change that to 25 or so and see how it works. You have to find a happy medium where the heat pump fails to keep up and runs all the time vs running on LP for a short while and getting things toasty in a hurry

 

[Sigarms]

It all comes down to price of electric and LP. Natural gas of course is a lot cheaper in most areas.

I just scratch my head when someone has an oil furnace (still have a bunch of them even in NC) and they want a new AC system, but don't want to spend a little more for a heat pump set up with the oil furnace. With the price of oil and how much you use that oil furnace below 65 degree outside air temp, the payback for the difference is pretty quick as long as you have a decent electric rate.

 

[Larry Caldwell]

No difference but the electric bill, mine is a 4 ton unit in our 2500 sq ft 2 story. Lots of difference heating a 1400 sq ft ranch vs a 2500 sq ft 2 story. Air has to be pushed a lot farther and a lot more variations in temp between floors. Plus our house was built in 1970. Newer construction is much more efficient. Although ours is all brick

Wow, install a secondary heat system. Your problem is not the heat pump, it's your house. Pushing 70 heating degrees in 1970 insulation is insane. Get a pellet stove or wood stove on the first floor to provide your primary heat any time you go over 40 heating degrees.

 

[Larry Caldwell]

Just FYI, SEER stands for Summer Energy Efficiency Rating, and is a measure of cooling efficiency. It doesn't mean much when it come to heating. Modern heat pumps run about 16 SEER for a middle of the road heat pump. Heating rating is the HSPF (Heating Seasonal Performance Factor). An average unit will have a HSPF of about 8.5 - 9.

Do your energy upgrades first. Insulation is the gift that keeps on giving. Replace doors and windows. If you buy a heat pump first, you will pay big bucks for an oversized unit and then pay big bucks as it tries to compensate for a leaky house. Your utility company should arrange a free energy audit for you.

 

[goeduck]

After disabling my strip electric heat when my wood stove can稚 keep up or when I am at work, my heat pump is running solo now. This morning wifey ran the Tstat up 4 degrees to 74 F when she got up and I measured the temperature at a close register to be 90 degrees. So it is picking up 20 degrees from 70 to 90 when it was 40 degrees outside. Is that normal?

 

[LD1]

After disabling my strip electric heat when my wood stove can稚 keep up or when I am at work, my heat pump is running solo now. This morning wifey ran the Tstat up 4 degrees to 74 F when she got up and I measured the temperature at a close register to be 90 degrees. So it is picking up 20 degrees from 70 to 90 when it was 40 degrees outside. Is that normal?

That sounds about right to me.

If you knew how many CFM your blower was, you could convert that temp rise into BTU......

When it gets colder outside.....might only get 80-85 degree air out the vents....but still able to heat the house....and still more efficient than strips.

 

[coldsteelva]

The real trick is to keep that heat your capturing/producing INSIDE the house. Definitely spend money on sealing the envelope before addressing what may be a perfectly serviceable HVAC.

 

[jwstewar]

I have the Dual Fuel, heat pump with LP back up. For Kansas it seems to be a pretty good set up. We have cold snaps but this year longer than normal. I have my heat pump locked out at 30 degrees, which means I run on LP under 30 degrees. I may change that to 25 or so and see how it works. You have to find a happy medium where the heat pump fails to keep up and runs all the time vs running on LP for a short while and getting things toasty in a hurry

Funny, I had my breakover point (Lennox abbreviates it BP in the thermostat) set at 25 because propane had been so expensive. Around here AEP keeps raising their rates to the point it is getting ridiculous. I just changed my breakover point to be 30 or 32. At 1.79 a gallon, propane is cheaper than the heat pump struggling to keep up and the house is warmer. We built the house in 2008, it is a 2-story about 3100 sq ft plus basement. Electric bill last month (read date of Jan 10th) was $397, but that is close to typical for us. That includes running heated buckets for the all of the goats, dogs, and chickens. That also includes using a 9,000 BTU A/C-Heat Pump-Heat Strip window unit in our 12x14 milk room in the barn.

 

[MacLawn]

I got an Ecobee thermostat over a year ago, love it!! It has paid for itself in less than 6 months. Then last month, I got Nest for other place. Both were from my power company at good discount. No way would I ever buy another Nest. Love the Ecobee. Research it, it absolutely save on heat/ac bill.

 

[dragoneggs]

I got an Ecobee thermostat over a year ago, love it!! It has paid for itself in less than 6 months. Then last month, I got Nest for other place. Both were from my power company at good discount. No way would I ever buy another Nest. Love the Ecobee. Research it, it absolutely save on heat/ac bill.

Uh oh... just installed a Nest. Why are you so bent on Ecobee vs. Nest? What makes that smarter (energy saver)???