Didn't pressure check.

ianh81

I need a sanity check. I recently finished up the installation of 1200' of tubing in my garage for a radiant floor heating system that went really well and they poured the garage floor today. During the process we decided to prep for the possibility of heating the driveway too. To prep for the driveway, I stubbed out (18) lines for the driveway loops and ran those through my garage slab. For the life of me, call it sleep deprivation, oversight, and/or inexperience I didn't pressurize the driveway lines prior to the garage floor being poured today. My question is this, when I utilize the driveway loops will the water pressure/expansion (I know it is low) cause the garage slab to crack? I never considered the fact that pre-pressurizing the system allows some tube expansion during the pour and only considered it as a means to check for damage. Did I effectively just shoot myself in the foot?

Jamie Hall

Shouldn't be a problem, at least assuming that you use reasonable pressures (like less than a few hundred psi). At least from the standpoint of cracking the concrete. Concrete is weak in tension -- but not that weak.

However... you did miss the opportunity to make sure that there were no leaks in those lines... or fittings...

Dave Carpentier

I'd be tempted to pressurize them before the concrete completely cures hard.
It does take a while.

GroundUp

The tubing doesn't crush under the weight of the concrete, there will never be any expansion in those lines unless they freeze some day while filled with water. Even then, the odds of hurting the concrete are slim to none.

hot_rod

Pressurize during a pour so you can potentially spot a leak and repair during the pour. It doesn't happen often that a tube gets damaged.

Back in the rubber tube days we drove concrete trucks over the tube. That made the gauge reading bounce

ianh81

Thanks for all the comments, I really appreciate it. The tubing is sleeved into and out of the slab so I assumed if there was any expansion it would occur at those places where it isn't constrained, but at the same time I had this vision of the tubing expanding ever so slightly and the concrete splitting.

hot_rod

when tube is encased completely in concrete it can no longer expand. So movement is inward.
however it is rare that every foot of tube is completely surrounded, especially with that nob type under slab insulation