[AT] More radiant heat.

[Henry Miller]

On Wednesday 26 October 2005 12:21 pm, Andy Glines wrote:

> I was really surprised that one of
> our members from a Scandanavian coutry said that they use up to 250mm of
> foam under the slab. 250mm = 9.84"  (1" = 25.4mm)!  Those guys definitely
> aren't losing heat to the ground.  One site that I visited suggested that
> you insulate around the perimiter but leave an area in the center
> uninsulated.  They said that the soil would act as a heat sink in this area
> storing heat in case of a power outage.  

When a local ice rink was torn down (after many years), the frost went down 20 
feet!    Therefore you should insulate your perimiter down at least 20 feet 
if you don't want to insulate the floor, because otherwise the heat will just 
go below the insulation and out.    I'd insulate the floor well, and use a 
thicker concrete slab to retain heat.   Perhaps with plenty of gravel above 
the insulation if I wanted more heat capacity, though I've never heard of a 
big need for it.

> A member of SIAM is a retired 
> concrete finisher and I asked for his input.  He said that everyone who has
> it loves it and there aren't many problems.  One thing he suggested was a
> thicker slab as he thought that the imbedded tubing may weaken the floor a
> bit.  I tend to agree whith his thinking.  Has anyone heard that the floor
> should be thicker?  How much?

I tend to agree, but I'm not qualified to answer.   I'd be surprised if it was 
more than 2 inches, but you should ask someone who can calculate the loss of 
strength from tubes.