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Old 09-19-16, 08:09 AM   #30
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
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Quote:
Originally Posted by Snail View Post
Hi Steve,

The benefits that you mention for radiant floors apply at least equally for ceilings. You say that the floor option makes sense as you were going to a concrete floor anyway. Since you are worried about having too much thermal mass, it would seem far more logical to eliminate the expensive, heavy concrete floor and go with the ceiling option, which has effectively no thermal mass, if you use a suspended metal radiator surface.
Misunderstanding (of me explaining my situation). Thermal mass is good - up to a point. The key is to match the time lag/storage with the climate it is being placed in as well as the energy costs.

A heated four inch (10 cm) floor, throughout the home, may be simply too much mass for the climate here in Oklahoma. The problem is that we have a mild winter associated with a large rise in daily temperatures from nightime lows. In a colder climate, this mass volume could be perfect.

For compromise, a two inch floor might allow the right amount of heat storage without the long lag. If the time constant for heat loss is long, then you can end up releasing heat in the middle of the next daytime (overdamped).

Too short a time constant and the house temperature goes up and down (underdamped). Much like an impulse to a car shock absorber, the dampening must be correct.

I am running some models now, but it "looks" like two inches is about right for my mild winters and significant daily temperature rise (20-30 degrees F).

This article talks about time dependent thermal dampening concept . . .

Thermal Mass - Energy Efficiency of Concrete


Steve
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consulting on geothermal heating/cooling & rational energy use since 1990
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