In floor heating causes SKY high electric bill

[Texas Proud]

Quote:

Originally Posted by TromboneAl 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.

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...

[bizlady]

dang-- but that still seems unlikely to run that much....

[TromboneAl]

Quote:

Originally Posted by Texas Proud 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...

OK, thanks. I had thought the mispost post corrected it to 100 sq ft.

[Texas Proud]

Quote:

Originally Posted by bizlady dang-- but that still seems unlikely to run that much....

I doubt you have a 15,000 watt heater system.. that is over 50,000 BTUs which could heat a small house...

Here is a calculator that says a 10X10 with poor insulation and Michigan winter would only need a 4,000 BTU system....


http://hearth.com/cgi-bin/btucalc.pl

[Dimsumkid]

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.

[Zathras]

Bizlady, is this a heat pump or resistive heat?
Our house is set up very similar.
Do they have an off peak meter for the heat pump? If so, what was that meter showing for use in Dec? We tend to be home more in the winter, bake a lot more, and so use more electricity. Our heat pump use has never gone over about 1800 kwh in a month (heat pump and water heater).
Also, if it is a heat pump system, did you say you saw 'pipes'? Was this in the floor itself? Typically the systems I have seem use tubing, generally Pex I think. If you saw copper pipes, that may be something to investigate.
Also, they really should have laid down insulation under the tubing otherwise you would be heating the ground, as others have said. I would guess this would double the bill.

Any details you can provide may be helpful. Good luck!

[bizlady]

It is tubes and not pipes in the floor.

The unit info is this:

• Thermolec - Model B-10U-FFB
• 10 KW
• 41.6 amps
• volts/ph/hz - 240/1/160

BTU 34120

It is a boiler I am told-- if that makes sense-- used only for the in-floor heat.

KWH in the home ran about 460 most of the month, and 600 Kwh in the colder winter months- which was before the in-floor hear was hooked up.

This month Kwh bill from Dec is 4750 kwh -- YIKES

[ls99]

Looks like they are using electric heater to run a boiler to heat the liquid circulating in the floor heating piping.

If the they wanted to find the most inefficient method to provide heat, they succeeded.

While having electric resistance wires in the floor would have been bad enough this setup takes the cake.

Edit add: entirely plausible that there is a leak in floor plumbing. Hot water leaking out, the automatic level control adding water to maintain water supply, thus constantly heating cold water to the pre set temperature.

Should find an independent hvac pro. who does not sell anything but his expertise in evaluating the SYSTEM as a whole, including heat load calculations. The electrician will likely verify that electrically the system works. He won't be interested in diagnosing system design or system operation.

Good luck/

[travelover]

Quote:

Originally Posted by bizlady The unit info is this: Thermolec - Model B-10U-FFB 10 KW 41.6 amps volts/ph/hz - 240/1/160 ..........

10 kilowatt heater at ten cents per kilowatt hour costs a buck an hour to run. 720 hours in a month....hmmmm

Seems like house would be sweltering if it ran that much of the time

[Dimsumkid]

Quote:

Originally Posted by travelover 10 kilowatt heater at ten cents per kilowatt hour costs a buck an hour to run. 720 hours in a month....hmmmm Seems like house would be sweltering if it ran that much of the time

Not so sure that's the case...basement heat will travel upstairs, causing the gas heated system upstairs to fire even less. So what shuts the system off?

[samclem]

Quote:

Originally Posted by ls99 If the they wanted to find the most inefficient method to provide heat, they succeeded. While having electric resistance wires in the floor would have been bad enough this setup takes the cake.

Exactly. The only way to make it less efficient would be to dump the hot water out into the creek after it heats the slab (and the rest of the continental plate).

Did the installer pull a permit? MN is a fairly "progressive" state--are there any laws or codes concerning the installation of such systems?

If the system is as you describe/assess (hydronic fluid heated by electric resistance without insulation beneath the slab) I'd guess the best things to consider now would be:
a) If there's sufficient headroom in the basement, put foam insulation atop the slab, hydronic tubes above that, and a floor. Heat the water with natural gas.
b) If there turns out to be insulation under the slab, consider converting to NG heating of the hydronic fluid.
c) Abandon the "warm basement floor" dream and add forced air heat to the basement. Some throw rugs in strategic locations will help keep feet warmer. Wall-to-wall carpets in basements, especially directly atop a slab, are an invitation to mold and uckiness.

[travelover]

Quote:

Originally Posted by Dimsumkid Not so sure that's the case...basement heat will travel upstairs, causing the gas heated system upstairs to fire even less. So what shuts the system off?

Yes, the heated air would rise, but unless most of the heat is sucked into the ground, the amount of electric heat being generated should just about heat the house.

As a comparison, I did an Manual J calculation for my 2500 square foot house and even at zero degrees outside it only takes 35,000 btus to maintain temperature.