Supended in Concrete or stapled to foam

Ideally

the tube would be placed about mid slab. Siggy has written several articles on the performance difference based on tube depth. Find them at www.pmmag.com may 2000 column. His model shows about a 30% difference between the tube at the bottom of a 4" slab, and 1.7" below the top surface. water temperature adjustments need to be made to equal the btu/ sq ft. output.

I will say suspending the tube exactly in the ideal location is easier said than done. i've used mesh and chairs as close a 3' on center and still get droops between them.

Caution needs to be taken when pumping concrete over elevated pex. the force of the mud flying down the tube has a tendenacy to float it to or through the top surface. It also leaves the tube vunerable to saw cut expansion control joints commonly used these days.

I'm not following the logic of how the tube could make the concrete weaker?

Adding water to concrete at the job site weakens the mix considerably. Every gallon of water added to a yard proper concrete mix reduces the psi rating by 200 lbs.

Lazy concrete finishers often add 8-10 gallons to get the mix to flow into place with the least amount of effort.

hot rod