In floor heating causes SKY high electric bill

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bizlady

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Maybe someone can give us some insight. We live in MN, so weather is cold. DD built a new home, and put in floor heating in the basement. They activated it this fall, and the electric bills went through the roof.

The house is new construction 2 story withgas heat on the main and second floor. But the added in floor heat added $500 this month to the electric bill, which is usually just $50. The foot print is 1000 sf. Others who have the same heat in the whole house do not have bills anywhere near this.

What can be wrong or what can be checked?
 
Something is way out of line for 100 sq ft at $450/mo. How expensive is your electric rate? Also, does your system have a thermostat that controls the floor heating? If not, I'd turn off the system, seems like it's running 24/7.

Maybe you meant 1000 sq ft? Sounds like you're better tapping the gas heat from the 1st floor to heat the basement instead of using electricity.
 
Last edited:
The thermostat setting.

Floor heat warms the floor, obviously, then the warmed air stratifies near the ceiling, leaving the middle somewhat cool. Resulting in folks turning up the thermostat. Add ceiling fan to disperse the stratified warm air, lower the thermostat.

Oh and do check for good insulation vapor barrier and air sealing. Putting a dead short on the end of a pair of wires in the form of electric heater is not an efficient method of heating.
 
What is the insulation under the basement? Is this the heat sink? Then I would check the basement walls. The winter frost level in MN is near 4 ft? I have an infrared temperature gun and have been checking temperatures all around my house and making plans on retrofits. I need to do some of the retrofits myself, and I have two 100+ year old houses. I feel the financial pain in the wallet, too.
 
Did they have electrical heat before the change?
We use gas, so I have no comparisons.. and besides, I'm in NJ
 
Ouch. I would want to spend a lot of time in the basement on the floor to take advantage of that $500.
 
I misposted, originally, it is 1000 SF (about 900 and some) and not 100. They have gas forced air on the main and second, and though they lived there a year, did not activate the basement heat until this year as they could not afford it until now.Energy charge: .103 per kwh

Monthly usage was averaging 400 KWH, November was 1400, and Dec 3400 Kwh.
 
This is very wrong.

We have an all-electric house (heat pump) and in the coldest winter we have had in the last seven years, with multiple days below 0°F, our highest monthly bill was around $300, and our electric rate is a little higher than yours.

I would find out exactly how this system was installed. It sounds like you may be heating the ground under the house.
 
bizlady, your #'s don't add up.


But the added in floor heat added $500 this month to the electric bill, which is usually just $50.

Energy charge: .103 per kwh

Monthly usage was averaging 400 KWH, November was 1400, and Dec 3400 Kwh.

So Dec added ~ 3000KWh. 3000*.103 = $309 added (probably some taxes on that, etc, but close).

Now, 3000KWh/30 days /24 hours is 4,160 watts if it was on all the time. At 220V, that's ~ 18A, so it should be on a 30A circuit.

Like others, I'd want to know how much time it is on. I also suspect that it might not be well insulated from the ground, and the ground is going to suck up all that heat. You never mentioned, is it more comfortable in the basement now?

You can check the meter yourself. Turn everything off at the breakers, turn on some known loads (10 100W bulbs) and check the meter indicators (varies with meter type - google for how to read them). Turn the heat on/off and note the change.

Electric is far more $ than heating with Natural Gas. Why didn't they do a PEX tube hot water fired from Natural Gas for this heat (you still need it to be insulated from the ground)?

This is why we need meters we can read from inside the house - increases like this would not go undetected for so long.

edi: braumeister - a heat pump is far more efficient than resistive heat (which is what I assume they have). I can't for the life of me understand why anyone would install resistive electric heat in MN when they have NG available. Even w/o NG, heat-pump would be the way to go.

-ERD50
 
braumeister said:
I would find out exactly how this system was installed. It sounds like you may be heating the ground under the house.
Click to expand...
My guess too. There is a lot of ground to heat before you hit the hot core. :)

Ha
 
braumeister said:
It sounds like you may be heating the ground under the house.
Click to expand...

Bingo!

Based on your numbers, It sounds like you are using an additional 3000Kwhours per month when the radiant heat is on, and not keeping the output in the house.
 
ls99 said:
The thermostat setting.

Floor heat warms the floor, obviously, then the warmed air stratifies near the ceiling, leaving the middle somewhat cool. Resulting in folks turning up the thermostat. Add ceiling fan to disperse the stratified warm air, lower the thermostat.

Oh and do check for good insulation vapor barrier and air sealing. Putting a dead short on the end of a pair of wires in the form of electric heater is not an efficient method of heating.
Click to expand...


When This Old House did their barn conversion and added hydronic floor heating they showed temp readings at floor level (82 degree) chest level (76 degree) and up some 20+ feet it was something like 56 degrees. Very impressive I thought. That's why I considered it for a loft space. Using a fan would eliminate a major comfort feature of floor heating.

Did they do their driveway also? If they did it sounds like they might have turned that on at some point.
 
Driveway is not done- just hte basement- less the utility room. What is a Hot Core?

If a moisture barrier was not installed (one may very well have been) what effect does that have? I know there is insulation below the pipes because we saw that during construction. Could the electrical installation or boiler be faulty causing this?

The basement is (was) very comfortable, but at this price- will be shut down. I feel so bad for them. Not only can they cor afford the extra $500 a month but they saved for a year to finish the installation for the heat- went all last year without.
 
And I was worried about using my 1500 watt space heater a few hours when it was cold downstairs... glad I am not this person...

But.. a few questions... wouldn't the basement be hot even if they were heating the ground:confused: I am thinking that there is a heater along the baseboards that is at first heating up the air... which then heats up the walls... which then heats up the ground... where is my thinking off:confused:
 
JJ1960 said:
When This Old House did their barn conversion and added hydronic floor heating they showed temp readings at floor level (82 degree) chest level (76 degree) and up some 20+ feet it was something like 56 degrees. Very impressive I thought. That's why I considered it for a loft space. Using a fan would eliminate a major comfort feature of floor heating.

Did they do their driveway also? If they did it sounds like they might have turned that on at some point.
Click to expand...

I missed that bit.

My experience repairing ceiling fixtures in a house with hydronic underfloor heating is that I was sweating working near the 10' ceiling while the owner was wearing a sweater with the thermostat set at 74F. Did not measure the temp, was sure hotter than at chest level.

Have not worked in houses with 20' ceilings.
 
You've got to put a meter on the electric floor. The inline equivalent of a Kill-a-watt. You can turn off everything in the house but the heater and look at your power meter to evaluate how much it's using.

Monthly usage was averaging 400 KWH, November was 1400, and Dec 3400 Kwh.
Click to expand...

So, you added 3000 KWH in Dec. The intergoogle tells me that "The WarmlyYours electric floor heating system uses 15 watts per square foot." If your heater draws 1500 watts, then that would correspond to it being on for 2000 hours/month or 67 hours per day. Not possible.

So perhaps there's a short somewhere.
 
TromboneAl- thank you- this is the type of info we are looking for.

We have scheduled the electrician who installed the unit to come take a look. This helped us explain what might be going on.... will let you know.
 
TromboneAl said:
You've got to put a meter on the electric floor. The inline equivalent of a Kill-a-watt. You can turn off everything in the house but the heater and look at your power meter to evaluate how much it's using.



So, you added 3000 KWH in Dec. The intergoogle tells me that "The WarmlyYours electric floor heating system uses 15 watts per square foot." If your heater draws 1500 watts, then that would correspond to it being on for 2000 hours/month or 67 hours per day. Not possible.

So perhaps there's a short somewhere.
Click to expand...


15 watts per sq. ft. X 1000 sq ft. = 15,000 not 1,500.. that is 200 hours/month or 6.7 hours per day... which is possible... and might be what is happening if very cold...
 
dang-- but that still seems unlikely to run that much....
 
Texas Proud said:
15 watts per sq. ft. X 1000 sq ft. = 15,000 not 1,500.. that is 200 hours/month or 6.7 hours per day... which is possible... and might be what is happening if very cold...
Click to expand...


OK, thanks. I had thought the mispost post corrected it to 100 sq ft.
 
Bizlady,
Don't think you answered if there was a thermostat controlling the system. If so, is it the Honeywell round mercury type? Check it with a level to see if it was set correctly. If not, it could be running continuously. Had a coworker that had this problem, couldn't believe the heat guys could make 3-4 trips and never checked the level on the thermostat.....I sent him my bill for the fix! The heat company installer was really embarassed.
 
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