Pre-stressed concrete and radiant

Craig Bergman

We have a client that installed pre-stressed slabs for his garage floor. They were going to be 8" thick with a 4" overpour for the tubes to be embedded. However...They ended up being 12" thick, leaving no room for an overpour.

The slabs have 7" holes on 2" centers running the 20' length. Can I get 1/2" tubing into these holes to provide radiant heat for his garage? What might the wisdom of the wall say??

Thanks

Craig R.

Tony_8

huh ?

7" holes on 2" centers ? Do you mean 2" holes on 7" centers ?

Craig Bergman

Sorry

I ment to say 7" holes on 9" centers

Tony_8

interesting

you should be able to get a few 1/2" tubes thru a 7" hole.
I would use Pex-Al-Pex, it can be rolled out straight and doesn't have "memory". Might want bigger tube than 1/2 ?
Seems you'd also have to seal the ends, or... fill it with light weight crete somehow.

hr

Is this

a suspended slab? can't imagine why else they would use pre stressed slabs. If so you will need to address the downward loss, somehow.

I'm not sure heating that air space would do much for that much concrete mass. How far from the top of the slab are the holes? What is the design heat load for the space?

hot rod

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Craig Bergman

Pre-stressed

This is a suspended slab. The G.C. plans to spray foam insulation under the floor. The holes are 2.5" from the top of the slab. The heat loss is just under 30,000 BTU/H.

I was thinking that we could drill through the bottom of the slab to get the tubes into the basement and to a manifold. I'm just not sure if this can be done.

Craig

Dave Yates (PAH)

don't shoot!

But this seems like a candidate for a furnace and warm air radiant! 7" openings sound like an ideal connection point for supply on one side and looped over to return down the next bay.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

hr

Be aware

of drilling any prestresses concrete. Often there is cable or steel reinforcing mats. Some are pre, or post tensioned. You really don't want to drill into one of those babies, under tension! Better get signed permissioin before you start perforating

Keep in mind the edge loss of that chunk of rock,also. I'm trying to picture how you would handle that "loss" it's usually a big number on slabs suspended like that. What about baseboard or radiant ceilings, they actually work nicely in garage applications.

hot rod

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"