[Strawbale] Hot water storage concept - insulation

[Corwyn]

On Mar 16, 2008, at 18:25, Tom Oswald wrote:

> Hi,
> We are working out ways to store heat in water-mass for home hot water 
> and limited/back-up space heating.  We plan to heat the mass by 
> passive solar, fire-box, and possibly surplus PV.  We are considering 
> using a concrete septic tank to hold the water in, even though it may 
> not be the most green material to use.  We are considering placing the 
> tank outside the foundation, under a deck, on the earth.  We want to 
> avoid using foam insulation around and under the tank as it is not a 
> green material.  We are thinking about using saw dust but are 
> concerned about it getting wet.  We are seeking suggestions on how to 
> do this most efficiently and most ecologically.

I would consider using foam insulation before I would use concrete.   
But first, I would move the thing inside.  Heat loss inside is heat 
gain (though it drops your hot water max temperature).  I can't think 
of a way to insulate a tank with sawdust outside.  Plastic bags might 
work for a while, until they broke.  And there is no way they will work 
under the tank.  If I could figure out a way, I would use cellulose 
insulation instead.

If you want to to give some specifics in the way of R-value, 
dimensions, etc. I can run some heat loss numbers for you.

Thank You Kindly,

Corwyn

-- 
Corwyn
Kermit didn't know the half of it...
http://www.greenfret.com/
corwyn at greenfret.com