Hi everyone, I am in the process of putting up some pex for an underfloor radiant system. Above is 1/2 plywood and 3/4 oak wood flooring. I have a question about the aluminum heat transfer plates. One manufacturer says to screw on side of the plates and use silicone in the omega shaped channel to prevent expansion noise. Another set of instructions says to just use silicone inside the channel and screw both sides. Anyone have any input either way?

We use extruded "heavy" aluminum plates in all of our sub-floor radiant heating system designs and installations. Higher faster installation, lower operating temperatures, no noise and higher outputs. Send the thin plates back along with the caulk and the rest of the hassles associated with thin plates installed below the floor.

Now if you want to install plates in the ceiling or wall you have the right product but you must use the right PEX sans the EVOH layer on the exterior, which will can make noise, especially if you do not use outdoor reset to control supply water temperature. Look to Warmboard specs for quiet pipe. It doesn't matter if you screw or staple as long as the plates are tight to the sub-floor. When we assist DIY radiant floor customers, or they assist us, we have them screw up the plates; in case they screw up...

Thanks Badger, yes the plates are for the the ceiling and floor joist. We opted for the thin 16g plates do to budget.

We always prefer PAP pipe in light plates to ensure less noise issues, and also reset water temp control. the only reason to screw a single side of a plate is in a ceiling application where drywall will be pushed against the plate after the tubing install, or in an above floor application where finish floor pushes against the plate in the end. in those cases, half staple is important so the plate can conform, otherwise you can get a "tin can" sound when you walk over the plates. generally if that happens it will go away eventually but you'll have a really annoying few weeks.

in joists, always staple or screw both sides of the plate. without that, you might as well cut the loose wing of the plate off and recycle it for cash for all the help it will give you.

Silicone is for heat transfer if the groove doesn't fit snugly. hopefully your plates are good and snug without silicone. if not, add some.