[Strawbale] re. Re: PEX, Concrete Slab, Fear of Death (by contractor)(Speireag Alden) (Speireag Alden)

[Speireag Alden]

On 2008, Jan 02, at 12:39, MKL wrote:

> are you saying the slab that uses hydronic heating is only heated  
> as and when you are in the part of the house above the hydronically  
> heated slab and you move the water heater (uncoupling the pex from  
> the water heater ?) to Éwhere?

     I don't know what that question means, but I'll try to answer.

     The water heater is currently located in the bathroom, because  
that's convenient.  However, that bathroom is going to become part of  
the mud room next year, and at that point I'll need to move the water  
heater, probably to the semi-conditioned space in the "greenhouse",  
just outside the new bedroom.

     When the old propane heater annoyed me enough that I wanted to  
stop fixing it over and over, I replaced it with an electric tank  
heater so that I would not have to worry about venting exhaust gases,  
because I was roofing over all of the good venting points and did not  
want additional, temporary penetrations which I would then have to  
take pains to seal.

     So, that's why I heat with electric, for the moment.

     As to how I move that hot water through the floor, I do that  
with a manual timer switch.  I turn it on, and it stays on for the  
period I selected, driving hot water through the floor.

> Not wishing to be seen as impertinent I do wonder if my question as  
> to the amount of insulation you used under the hydronic heating  
> slab was in some way inappropriate?

     I'm sorry; I must have missed it.  R-20 under the earthen-floor- 
and-other-mass.

>>      Eventually, most of our house heat will be solar and wood.   
>> The ratio will depend on how well the solar part works out.
>
>
> ÆÆ The use therefore of the radiant slab is then "temporary" (and  
> electric heated water running through the slab will eventually stop)

     Yes and no.  The radiant floor is not a heat source; it is a  
distribution device.  In my plan, things will be set up such that I  
can drive hot water through the radiant floor.  Eventually, that hot  
water will be heated with a solar hot water collection system,  
stored, and drawn out of storage as needed.

     I could heat that water electrically, but I don't plan to, once  
other sources are providing heat.

> Or will the slab still receive passive solar heated water and  
> bypass the electric heater?

     Yes.

> in the event (god forbid) of immobilisation during a wood heat  
> requiring period one could always substitute the electric/hydronic  
> system for the wood stove

     I could, yes, but I'm not planning on it.  My local electrical  
power is non-renewable, and expensive.

> or do you mean you will burn wood to produce the heated water for  
> the hydronic system? Or both possibly?


     No.  If I burn wood in the masonry stove for the purpose of  
heating the house, the masonry stove should do the trick without any  
waterborne re-distribution of heat.  It will be centrally located in  
a pretty open plan, and the portions of the house which don't face  
the stove are the back bedrooms and bathroom, which are earth-bermed,  
and will be the last to get cold.

-Speireag.