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Old 11-05-09, 04:05 PM   #14
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Originally Posted by Daox View Post
I wouldn't try to get rid of too much weight as it'll detract from that.
There's a lot to be said for thermal mass...
  • It's generally cheap.
  • It doesn't use any power.
  • It has no moving parts.
  • It's very quiet.
  • It's extremely reliable.

There are also some things to be said against it...
  • It is bulky.
  • It is heavy.
  • Its weight must be accounted for in structures that support it.
  • It must be correctly sized to enable it to absorb and release heat at desired rates.
  • Thermal inertia can be your friend and your foe.

So in a retrofit, things are more challenging. I did a calculation on what is to be my 'test room' (A=144 ft.sq.)and determined that a 1.5 inch slab floor would weigh 2610 pounds (Density of concrete = 145 lb/ft.sq.) 2610 pounds.

That's a lot of weight.

I also did a calc to determine how much water would be required to have the equivalent thermal storage, it came out to being close to 80 gallons. so, I could pick up a used 80 gallon water heater and put it in the basement, where it would be out of the way, and not stressing my floor supports, and pump heat into the tank and draw the heat out as required.

There are down-sides to that plan
  • If the floor 'leaks heat', it will leak into the heated space, but if the water storage tank leaks heat it will leak it into an empty basement.
  • I have to contend with pumps, controls, etc
  • I am dependant on electricity.

There's also the angle of phase change materials. I tried some tests with Glauber's Salt and was not so thrilled with the initial results, however this guy had great results. They have been tried in floor tiles, drywall, etc. Personally, I have yet to try but hold out great hope for calcium chloride hexahydrate (AKA: snow melt salt) which has a page at BuildItSolar.

Here's an awsome list of PCM papers.

But this one, Carl Vener's Dissertation, gets cited more often almost any other PCM paper. the right choice is really an array of choices. It's a matter of choosing the right alternative, given all the convening elements.

So much to consider, so little time...



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Last edited by AC_Hacker; 11-05-09 at 04:09 PM..
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