[Greenbuilding] Hydronic Radiant Underfloor Heating

[Corwyn]

On Oct 15, 2007, at 07:28, Gary Viljoen wrote:

> By 'polystyrene' I mean compressed foam boards used for insulation.  
> Is that
> what you are referring to as 'rigid insulation'?

There are other rigid insulations, but yes, extruded polystyrene (XPS) 
is the usual one.

> And does your 'poly' refer to thin plastic waterproof sheeting instead?

That is polyethylene sheeting, yes.

> So, if I'm correct and working from bottom to top, I start with:
>
> 1. Well compacted and level base, then
> 2. Compressed foam/rigid insulation layer on top (with an additional 
> strip
> running along the foundation walls), then
> 3. Plastic waterproof sheeting on top of this, then
> 4. Steel mesh positioned at approx 40mm above this waterproofing layer
> 5. Hydronics piping tied directly onto the mesh, then
> 6. Concrete surface bed poured over this, then
> 7. Screed to follow
>
> Please let me know if that sounds right.

Sounds right.
>
> Any ideas for a 'greener' product to use for the under-slab insulation
> (greener than the compressed foam - polystyrene - insulation)?

Still looking for one.

>
> Also I would like some input on how to lay the pex piping.  What is the
> optimum length per square meter? Meandering pipes or tight turns??

It was recommended to me to use a double spiral.  Consider the input 
side and output side together as one unit (separated by the desired 
spacing), and spiral it around the room (or section of the room) 
towards the middle.  Keep the bends as easy as you can.  This way the 
hot part of the pipe is intermixed with the cooler part of the pipe and 
the hottest part is on the perimeter.

Thank You Kindly,

Corwyn

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