In floor heating causes SKY high electric bill

[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]

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]

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]

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]

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.