[Strawbale] PEX tubing in floors

[Corwyn]

On Apr 29, 2007, at 00:15, Raftercat5 at aol.com wrote:
> We plan to use  solar
> hot water, run by a solar pump, to heat the floors in the winter.   
> When the
> sun is not shining, it will automatically kick over to propane heating 
>  the
> water.

Concrete has a lot of thermal mass.  You may find that it will retain 
the solar heat for a long time, and you will not need the propane 
except occasionally.  Make sure that you have some control over when it 
gets used.  No point in heating the slab just before the sun rises for 
instance.

> My question is:  Can it work to cool the floors in  the summer by
> pumping cold well water thru the PEX tubing too?

Yes.

>  I'm  wondering if there would be
> any kind of moisture problem from condensation.  I think not, as where 
> would
> the moisture come from, if it's  not in the ground where the PEX will 
> be, which
> is on top of plastic sheeting,  and under concrete?

Yes, you will get condensation anytime the dew point of the air is 
higher than the temperature of the concrete.  Check you local weather 
bureau for how often than happens.  The water will come from the air, 
not through the concrete.

> Also, I'm concerned about the depth of the tubing into the concrete.   
> Would
> there be a chance it could work its way toward the surface of the 
> concrete
> right after it's poured, thus leaving it vulnerable to nails when the 
> interior
> walls are built?

The tubing should be in the middle of the concrete, attached to rebar 
or wire mesh (I used cable ties), and the concrete pourers will 
endeavor to ensure that it stays there.  But it is not precision work, 
and most concrete nails would be long enough hit the tubing even if 
placed perfectly.  Best to keep the tubing away from where the walls 
will be (or forego nails).

Thank You Kindly,

Corwyn

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