radiant floor

[bunks-tj]

I was talking with a buddy this weekend, about radiant heat in his kitchen. he was talking about how much he loved it.

I mentioned that you see a lot of garage/work spaces heated with radiant floor hear (h2o), but that i had never seen a garage space heated with electric radiant heat. I assumed that wires in a concrete floor for some reason do not heat the floor as well as water does.

Any insight is appreciated.

thanks

 

[sands35]

You can do electric resistance mats under tile. I don't think you want them in a slab though. You can do a hydronic floor with an electric water boiler though.

Have you done the math on cost per BTU for energy sources available to you?

 

[bunks-tj]

You can do electric resistance mats under tile. I don't think you want them in a slab though. You can do a hydronic floor with an electric water boiler though.

I guess the question was why not in a slab. And my answer (guess) was the ever powerful $. figured it would cost too much in electric to heat a slab that way. I assume that heating water and running it through the slab is cheaper than actually heating the slab with electric

Have you done the math on cost per BTU for energy sources available to you?

no it was more just premise

 

[Randy in Maine]

For me (electricity at 14.5 cents per kwh) hot water (via propane or NG )is just a lot cheaper over the long term. Gobs cheaper.

Plus it can be done with a boiler located in the house) to keep sources of combustion out of the garage.

 

[sands35]

For most folks, gas is a lot cheaper than electric. The only exceptions might be a location that has cheep hyrdro power.

The nice thing about a hydronic system is that you attach just about any heating source to it you want.

 

[bunks-tj]

But the downside is that it has to be on all the time to keep the hoses in the floor from freezing, correct?

 

[sands35]

No, it does not. The concrete floor has a lot of thermal mass. In the winter, with ~0-10*F ambient, my system only runs for probably 10-20 minutes an hour when set to 40*f (not occupied), to 50*F (occupied) (though I never bothered to record actual run time data). There is also anti-freeze (specific for hydronic systems) in the water.

It needs to be insulated properly. The more insulation in the walls and ceiling and the degree to which the building is air tight impact the thermal efficiency of the space. Under-slab is typically R-10 of sheet foam. Walls run from r13 and up and ceilings start at r30 for a garage. More is better, to a point. The devil, so to speak, is in the details. Taping and sealing off external outlets, dressing soffit vents, garage door seals, etc.

 

[bunks-tj]

Excelent information. Thanks!