[Strawbale] PEX, Concrete Slab, Fear of Death (by contractor)

[Sherwood Botsford]

Shody Ryon wrote:
> Laren on the littlehouses yahoo group has been
> promoting 2L soda bottles filled with water in its own
> thermal insulation envelope in the attic where heat is
> allowed to rise up and be stored there. If you already
> have thermal storage in your slab, it may not be
> necessary unless you wish to store additional warmth
> from the sun and reduce any fuel costs, usage or build
> a super insulated floor with less thermal storage,
> perhaps in another project. I don't really know about
> this, I am just putting it out there, trying to
> understand some of the variables. I am thinking that
> for a hydronic system insulated water tanks could be
> installed in the attic, if that is unused space. They
> could be prehated with solar collectors and sent from
> those takns to the other heating system. My neighbors
> are selling their solar water heaters off both of
> thier houses, because of "issues" ... so I am
> wondering if they work well in this area of the north
> west, though a lot of people claim they do work well.
>   
Water is heavy. To get significant water in the attic space requires a 
much more robust roof structure.  And while water is cheap, containers 
to keep it for 50 years or so are not.  I would not advise putting it in 
your roof

Put the water in a tank under the house.  If you want to harvest attic 
heat, run a circuit of tubing between that tank and the attic space.

Dirt is even cheaper than water+container.  A cubic foot of water has 
about the same thermal storage as about a half cubic foot of water. 
(Rough calc:  Dirt has a specific heat of about 0.2, but a density of 
about 2.5)