Suggestions for electric a/c usage

mimino · 05-20-2011, 12:18 PM

Hello, all!

We've recently moved into our new home (2-story duplex, not sure about sqft.) that is all-electric. Our last bill was abut 1000kw/h, which translated into about $115. We did use the heater for a week or two rather extensively(wife gets cold when i', not lol), so i can only imagine how the bill will look in the winter.
My question is: is it cheaper to let either a/c or heater be on all the time at a regulated temp: around 75F or let the place heat up/cool down during the day, and once we're back from work, turn it up/down to the desired temp?
I think that #1 should be cheaper, since the system would have to be on less time than in #2.
The house seems to be insulated ok, but only winter will tell for sure.
Any tips, suggestions are greatly appreciated. If this was covered before, I apologize, as I haven't done any searching.

Thank you, all!

bob22 · 05-20-2011, 04:26 PM

If memory is correct (I can't remember if it is though), a temp swing of about 5-7 degrees is likely economical to recover from (either up or down). Beyond that (everything depends on the home's airtightness (not a word?), heat/cool system efficiency), type of system, outdoor temperature and wind speed, it starts to cost more to heat/cool. Does that make sense?

If interested; read article at:
http://www.google.com/url?sa=t&sourc...JVI3eQ&cad=rja

Seems to put it all together fairly well and is short; discusses differences between gas and heat pump systems well and relative impact of setback savings. Newer technologies may need new studies however.

Another site suggests:
"Energy experts do not recommend thermostat setbacks for houses that are running heat pumps. Setting back the thermostat on these systems causes the heat pump to run inefficiently, canceling out any benefits, Pedersen says."
at: http://www.google.com/url?sa=t&sourc...1Mf8cQ&cad=rja

Others will have suggestions I'm sure on this.

**beenthere** · 05-21-2011, 06:03 AM

All electric heat means what? Electric baseboard, electric resistance furnace, or a heat pump with electric aux heat?

mimino · 05-21-2011, 11:26 AM

i knew that i'd get owned here

i'm a total newb to this and have no clue what kind of system we have. any quick tips on how to check?

gregzoll · 05-21-2011, 11:47 AM

We only used 657kw/h, so your use is in line for a all Electric home. Check with your neighbors, and if your utility has on their site a way to compare to others with the same stuff in the home, it will tell you where you rate. Our local gas supplier (Ameren) always shows us at way under in use for gas compared to others. I joke with the meter reader all the time for the electric, and at the home show, that some day they will audit us to make sure our meters are reading correctly.

**beenthere** · 05-21-2011, 02:15 PM

Quote:

Originally Posted by mimino

i knew that i'd get owned here

i'm a total newb to this and have no clue what kind of system we have. any quick tips on how to check?

When your heat is running, is the outdoor unit running? If so, its a heat pump.

mimino · 05-22-2011, 10:41 PM

nope, the outside unit did not come one with the heat "on."

**beenthere** · 05-23-2011, 05:13 AM

You may want to consider getting a heat pump then. It can reduce your heating bill by 1/3 to 1/2 per month. Which is a big savings over a years time.

Letting the house warm up or cool down a few degrees while your not there, will save some money.

gregzoll · 05-23-2011, 09:11 AM

Actually, it depends on the utility company if the Heat pump will save. Also, letting it warm up will not save money. What will save money, is making sure that the windows & doors are air tight, that the lights are shut off when you do not need them, insulate the home, especially the attic area, use ceiling fans in bedrooms. Running the air at the set point that it was designed for is better. Ours was designed with the house temp at 73, but some times need to set it at least a degree or two lower when we are home all day, because it does not always cycle like it should (yes, should get the newer thermostat that cycles the fan).

But the one thing I can agree on beenthere, is if you are gone for eight hours or longer during the day because of your work, or gone all weekend, bump the thermostat up to around 76-78 to not have it run to cool the house. If you have a pet, do not set any higher, because then you are endangering the pet's health.

**beenthere** · 05-23-2011, 06:02 PM

Doesn't matter about the utility company. A heat pump will save money, since it will use less electric to provide heat then electric resistance heat.

gregzoll · 05-24-2011, 08:13 AM

Quote:

Originally Posted by beenthere

Doesn't matter about the utility company. A heat pump will save money, since it will use less electric to provide heat then electric resistance heat.

Yes it does. Where I live, it is the same on costs to use either gas or Electric, but majority choose to stay with conventional systems, not a straight heat pump, even though the city owned utility gives a huge rebate to use a Heat pump. Some areas that electric costs are high, you see less people using Heat pumps. It comes down to costs to run, vs costs to savings when you look at the big picture.

moondawg · 05-24-2011, 09:10 AM

Quote:

Originally Posted by gregzoll

Yes it does. Where I live, it is the same on costs to use either gas or Electric, but majority choose to stay with conventional systems, not a straight heat pump, even though the city owned utility gives a huge rebate to use a Heat pump. Some areas that electric costs are high, you see less people using Heat pumps. It comes down to costs to run, vs costs to savings when you look at the big picture.

No, it doesn't. An electric heat pump will cost 1/2 to 1/3 as much per month as an electric resistance furnace, regardless of how much your unit cost for electricity is. That's the whole reason for having a heat pump. They "pump" heat from the outside air to the inside air. (or the other way around in the summer) It's much more efficient than using electricity to heat up a piece of metal to gain heat.

You've also confused the issue by adding gas systems into the discussion. Operation of a gas furnace may currently cost about the same as electric in your area. In many areas outside of the Northeast (some of the most expensive electricity in the nation,) this is NOT the case.

Since it sounds like the OP has a resistive electric furnace, the cheapest, easiest and fastest way for him to lower his monthly bill is to install an electric heat pump. It will be marginally cheaper than a conventional A/C in the summer too, a nice bonus.

gregzoll · 05-24-2011, 01:19 PM

Using a Heat Pump for costs on electric depends on the provider. A Heat Pump is not going to magically make your costs for use of electric or gas automatically go down. A heat Pump costs the same to use, as using a AC & Furnace. If you believe the hype that a heat pump is more efficient, than a high efficient 91% or better furnace & 16 SEER or greater A/C, it is false info.

moondawg · 05-24-2011, 02:11 PM

Quote:

Originally Posted by gregzoll

Using a Heat Pump for costs on electric depends on the provider. A Heat Pump is not going to magically make your costs for use of electric or gas automatically go down.

You're right, it's not magic. A heat pump is more efficient than an electric furnace. It uses less electricity and therefore makes your electric cost go down. Of course, it doesn't make your gas usage go down. In the case of the OP, his home is all electric. NOTHING will make his gas cost go down ... he has no gas cost.

Quote:

A heat Pump costs the same to use, as using a AC & Furnace.

Well, it CAN, but it's highly dependent on the efficiency ratings of the furnace, A/C and Heat Pumps involved. It's also highly dependent on what you pay for electricity, gas, or propane. You understand that these things are not the same price everywhere, right?

Quote:

If you believe the hype that a heat pump is more efficient, than a high efficient 91% or better furnace & 16 SEER or greater A/C, it is false info.

You can't really compare the efficiency of a heat pump and a gas furnace... they run on different fuels. You can only compare the cost. If you have cheap electricity and expensive gas, you can operate an 18 SEER/9 HSPF Heat Pump cheaper than a 91% efficient gas furnace + 16 SEER A/C.

Again we digress from the OP's ALL ELECTRIC home. A high-efficiency HP WILL reduce his electric heating costs by at least half. More if his utility gives him a rebate or cheaper electric rate for using a heat pump. If the HP has a higher SEER rating than his existing A/C, it will also reduce his electric cooling costs.

**beenthere** · 05-24-2011, 07:18 PM

Quote:

Originally Posted by gregzoll

Yes it does. Where I live, it is the same on costs to use either gas or Electric, but majority choose to stay with conventional systems, not a straight heat pump, even though the city owned utility gives a huge rebate to use a Heat pump. Some areas that electric costs are high, you see less people using Heat pumps. It comes down to costs to run, vs costs to savings when you look at the big picture.

Reread my post. I was comparing a heat pump to electric resistance heat. Never said anything about gas heat.

There are a few areas that either have gas that is cheap enough or an electric rate that is high enough to make a heat pump not worth while when gas is available. but compared to electric resistance heat, a heat pump is always more cost effective. And since the OP is talking about an all electric house. A heat pump will be much cheaper to heat with then just electric resistance heat, no matter what the utility is charging for the electric.