heat pump -elect coils

My daughter is complaining about high heat bills. i bet the elect resistence elect coil is on a lot. how do i tell when the coil comes on? and how do you turn it off? what turns it on? when temp is below 32? if compressor is ok, why would coil come on? she had the system checked and they said ok. wonder if they checked out operation of coils. thanks for any insight. bill in Maryland

Reply to
bill
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One big thing to watch for with a heat pump is turning it up and down. Does she change the temperature or just sets it at one place and leaves it there. Most of the time the heat strips will come on if you go up about 3 or 4 degrees at one time.

Reply to
Ralph Mowery

Yes! That is a major drawback in some circumstances. I used to have all-electric. The thermostat fortunately did have a light to indicate when the electric backup was on. I'd turn the heat down quite a ways when I was gone. Upon return, I'd turn it up just a few degrees at a time, keeping the electric backup from coming on. I eventually got around that by putting a toggle switch on the thermostat. The backup would only come on when I wanted to let it; I could set the heat to warm up however far I wanted without worrying about the electric backup.

Reply to
websurf1

The electric heaters come on when the room temperature (at the thermostat) falls more than a few degrees below the set point. They also come on when the heat pump (outside unit) goes into defrost.

In some installation, the thermostat has a lamp that comes on when the resistance heating is being called for.

My system came with a total of 60 amps (about 15kw) of available resistance heating. In my case, it was easly to arrange things so that only 20 amps of resistance heating would be switched on. Obviously, when it gets VERY cold outside, the inside temperature sags! It's a question of money vr. comfort.

We compromise with a combination of LPG ventless heaters and small electric heaters that give some extra heat where the people are.

The quick and dirty way to save money is to turn the thermostat down to, say, 60 or 65 and use small electric heaters (750 watts) where you want the extra heat like when you are watching TV. Waterbed heaters and electric blankets also make it possible to be comfortable when the house as a whole is on the chilly side.

I agree with the other poster who said that you should pick a thermostat setting and leave it alone. Timers cause more problems than they solve when you have a heat pump.

Reply to
John Gilmer

This is a very timely conversation for me. I just replaced my aging heat pump with one of the top of the line Carrier units. The literature estimated I could save as much as 60% over the 10 year old unit. (BS of course) Last months electric bill just came in and I used more electricity than the same period last year. Temps have not been unusual this year. This unit came with a set back thermostat and I drop the temps overnight about 8 degrees. As you can imagine the heat strips kick in when it tries to bring the temps back up to daytime levels. I was wondering if I was wasting more power than I was saving by running the unit this way. Is there any temp setback that might give you some savings or is it really best to leave it fixed?

Rich B

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Reply to
Beach Trading Company

Face it, heat pumps are the most ignorant system ever developed and suffer from a basic design fault. The lower the temperature, the less efficient they become and nothing will help the electric bill from skyrocketing. Heat pumps are ONLY effective in the few southern states where the temperature does NOT go below 40 degrees for any extended length of time. Below 32 degrees, they are a total joke.

Reply to
BobR

I didn't install any resistance heating, just a clock that runs when the system wants to turn it on. I light the wood stove instead :0

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

Reply to
nick hull

With all due respect, Bob, a properly sized heat pump can continue to provide economical heat at temperatures well below 0C or 32F.

The Nova Scotia Department of Energy has a chart that compares the operating costs of various heating systems and an air source heat pump with a HSPF of 6.5 (COP of 1.9) is shown to be less expensive than electric heat, oil, propane and wood pellet, and competitive with that of a mid-efficiency natural gas furnace.

See:

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For an older home with a heat demand of 80 MMBTUs per year, the cost of electric baseboard heat is said to be $2,851.10; that same home equipped with new oil-fired boiler operating at 83% AFUE is $2,559.71 and a condensing propane unit with an AFUE of 93% will set you back a whopping $3,372.12. By comparison, the annual operating costs of an air source heat pump are $1,500.58.

Note that the numbers for oil and propane heat are based on fuel cost of $0.85 per litre and, at this time, oil and propane are running at $0.95 and $1.05 a litre respectively, so the relative performance of an air source heat pump is even better than what's shown here. Note too that our winters are comparable those of Minnesota (e.g., Minneapolis-St. Paul at 7,882 HDD, versus Halifax, N.S. at 7,861 and Truro, N.S. at 8,132 HDD), so this isn't exactly what you'd call a "southern" climate. Finally, a mid range heat pump with a HSPF of 8.5 would be 30 per cent more energy efficient than the one used in this example.

Cheers, Paul

Reply to
Paul M. Eldridge

Nice to know you are so fuquering stupid BobR. Get a clue and a brain and come back when you actually know something useful. Heat pumps work very well. Mine heats my home until about 17-18 degrees outside. Then it starts losing temperature so the back-up heat kicks in. I'll sell you a home with straight electric heat and I'll take the same EXACT home except I get a heat pump. We'll compare bills each month. You'll be hurting. Bubba

Reply to
Bubba

Comparing the Heatless Pump to pure electric heat might be a valid point but comparing to Natural Gas or even propane is a damn joke. Yes, mine also heats down to 17-18 degrees but in order to do so it must run almost continously and the electric bill for winter heating is double my bill for cooling in July and I live in DALLAS where it doesn't really get all that cold but it does get that hot. I have had it checked, checked, and checked again and even the Air Conditioning people admit that they are worthless pieces of crap.

Reply to
BobR

Yes, around 20 or so outside it seems to run 24/7 or something like that, HOWEVER........................ The next time it is that cold out, go out and wrap and amperage meter clamp around the run or common terminal of the compressor and not the amperage draw. Now, wait till it is 95 outside or some sweat busting temperature like that and measure that same wire with your amp meter. BIG difference. Heat pumps work if installed correctly paying careful attention to equipment sizing and duct sizing. No, its not as warm as gas, oil or propane but saves tremendously for those that only have the option of electric. Bubba

Reply to
Bubba

A heat pump using ground heat and cooling would probably be as effective as anything available, gas or otherwise. The problem with the heat pump and most air conditioners is the reliance on ambient air temperatures which are totally ineffective at the time they need to be the most effective. The colder it gets, the more you need the heat and the less it is available. Likewise, when its super hot outside, you can't get any cooling out of the hot air. The only really effective method would be to bury the evaporator coils deep in the ground where the ambient temperature will remain almost constant.

That system is now gaining acceptance in many areas and is proving both effective and cheaper. Unfortunately, nobody in my area knows crap about it and even if they did, the soil around here is so unstable that it may prove ineffective.

Reply to
BobR

Bill,

Feel free to offer this factual information about air-to-air heat pumps to your bloggers.

1) Heat pump installations work best in locations where the heating load in winter nearly matches the cooling load in summer. This is usually not the case.

2) Heat pumps work best when maintaining a constant set point (i.e. no drastic set point changes or night setback).

3) A heat pump cannot supply all the heat a building will need except in warmer climates without supplementary resistance heat. A heat pump is basically a cooling unit and is typically sized for that purpose. Over sizing the unit to gain heating capacity will result in poor summer operation. The oversized unit will short cycle, causing inadequate humidity control.

4) It is essential that the defrost cycle be working properly or airflow will be restricted through the outside coil at below freezing temperatures lowering heat transfer and efficiency.

5) The resistance heat is in use during the defrost cycle.

6) Heat pump efficiency is mathematically greater than electrical resistance heat when it's warm outside. Coefficient of Performance for heat pumps are rated at 47 degrees F.

7) A heat pumps capacity, hence its efficiency drops as outside air temperature drops. Efficiency drops rapidly below 32 degrees F.

8) Heat loss from a building goes up as outside temperature drops.

9) The key to greater heat pump performance is capacity selection (sizing). See 1 and 3 above.

10) The most energy efficient heating or cooling system is the one that's not operating. Insulate and lower the set point.

Reply to
bill

Bubba wrote in news: snipped-for-privacy@4ax.com:

And it needs the right coil in the air handler...but that falls under "if installed correctly".

I've seen & heard it often when someone's heat pump goes they just get another new or used and install it. My understanding, and I am by no means well informed on heat pumps, is the coil must me matched to the unit for max efficiency. Often a larger HP is installed because of the bigger is better mindset. But even if the same tonage is installed the coil still must be matched.

Anyone with some true HVAC knowledge feel free to back me up or shoot some holes in my comment. Learning from my own mistakes is experience. Learning from others mistakes is wisdom.

Reply to
Red Green

BobR wrote in news: snipped-for-privacy@j78g2000hsd.googlegroups.com:

I believe it's called something like geothermal heat pumps. I think it was in a monthly magazine from a NC utility company I saw an article on them. Study from some outfit where test systems were installed in various parts of the country. One was Burlington VT (about 40 min from Canadian border). Pretty positive results if I recall. Overall design, installation and ongoing costs I do not know.

Reply to
Red Green

Thanks for answering my piece of the question. I called the company that installed my heat pump yesterday and they recommended that I not set back more than 5 degrees. The aux heat strips automatically kick in if the temps need to be raised more than 3 degrees and more strips run the longer the unit is working to raise the temps. Based on that I've set the overnight temps to drop 2 degrees and I'll see how that works. I'm in SC and Feb is typically the highest wintertime usage so it will be interesting to see the impact of having a more constant temp.

Rich B

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Reply to
Beach Trading Company

snipped-for-privacy@j78g2000hsd.googlegroups.com:

It is the only method I have seen yet that would provide an equally effective benefit in both summer and winter no matter the local climate. The major difference would be in northern colder climates the heat exchanger would need to be buried deeper in order to find a stable temperature zone.

Reply to
BobR

Beach Trading Company wrote in news:cdf034d7-ffb6- snipped-for-privacy@d21g2000prf.googlegroups.com:

You may have a couple of options of what delta it kicks in at depending on the thermostat. Set via digital or by jumpers inside. Check the instruction sheet.

Another option is if you have an extra program available you could bring it up 3 degrees at a certain time then an hour later bring it up another few.

Not sure if you realize that once the delta is within the setting the strips should kick off and pump continue to run until temp is reached (plus maybe 1 degree).

Red...

Reply to
Red Green

Thanks for that Red. I'll try your suggestion of stepping it up. That sounds like a great idea.

Rich B

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Reply to
Beach Trading Company

That's what you get for using an air source heat pump with resistive backup (and probably keeping the temperature a lot warmer than you need to) - that's the worst heat pump combination there is.

Air source heat pump with gas backup is cheaper to operate than straight gas.

Ground or water source heat pump with electric backup is also cheaper than straight gas. In fact, a geothermal will usually not use the backup except momentarily even when it gets as low as -30F to -40F.

In geothermals, except in extreme cold (long duration < -30F), the backup is really only there to keep you from freezing if the HP fails outright.

Reply to
Chris Lewis

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