Radiant Floor Conduit and Insulation

[Friartuck]

Like others in this forum, I too am planning on radiant floor heating (25X35) for the shop as new construction in Southeastern Penn. The earlier posts on this topic have been an immense help. The most significant take away is the importance of good insulation.

1. I have seen several photos that show the 1/2 inch pex entering/exiting the slab through plastic or PVC conduit which appears to be 3/4 inch. Is there a purpose for that? Just a convenence to guide the pex while doing the slab pour?
2. Regarding the Extruded Polystyrene Insulation from Owens Corning, what is the differance between FOAMULAR 400, 600, and 1000? The data sheets shows them to have similar sizes (24X96) in 1, 1.5, 2 and 3 inch thickness. So what is the differance?
3. Is there a preferred layout like the Reverse Spiral Return suggested by Radiantec in the whole slab or simply do five loops as 7-8 foot wide segments where all the loops meet back at the manifold (in the corner in my case)?

Chris

 

[Possum]

1. I have seen several photos that show the 1/2 inch pex entering/exiting the slab through plastic or PVC conduit which appears to be 3/4 inch. Is there a purpose for that? Just a convenence to guide the pex while doing the slab pour?

They are electrical conduit L's. They offer a little extra protection to the tube, mainly when the concrete finishing is going on.

2. Regarding the Extruded Polystyrene Insulation from Owens Corning, what is the differance between FOAMULAR 400, 600, and 1000? The data sheets shows them to have similar sizes (24X96) in 1, 1.5, 2 and 3 inch thickness. So what is the differance?

The number is the compressive strength in psi. - ie. Foamular 400 is 40 psi, 600 is 60 psi, etc.
You could probably get away with Foamular 250 and it comes in 4'x8' sheets.

3. Is there a preferred layout like the Reverse Spiral Return suggested by Radiantec in the whole slab or simply do five loops as 7-8 foot wide segments where all the loops meet back at the manifold (in the corner in my case)?

That question will probably net you a lot of answers. For a single room (zone) shop layout I wouldn't think you would need too elaborate of layout. Spacing is more important.

 

[Friartuck]

Possum,
Thanks for the reply. I just found out what the Foamular numbers meant when you replied. Essentially the 400, 600 and 1000 rated boards are intended for serious commercial applications and not available to the general public (at least in single sheets). The 1000 is apparently rated for airline runways. So Foamular 250 it will be. Any suggested sources in York or Lancaster counties in Penn??