Radiant heat question:
I am finally getting ready to pour a slab on the lower floor of our home (currently perimeter foundation). Lower floor is above grade on one side and about 3’ below grade on the opposite side of the home. Upstairs floor has radiant tube embedded in 1-1/8†T&G plywood (installed specifically for the radiant tubes).
I’m in a very mild climate in california. I am considering two options for installing the radiant heat in the lower floor. Option one is to embed the radiant tubes in the new concrete slab. The other option is to duplicate the top floor install by embedding the tubes into 1-1/8†T&G plywood and then install the finished flooring on top.
I’m partial to installing the tubes in T&G plywood mainly because the climate here really doesn’t require heating the home 24hrs a day throughout the winter. I prefer a quick heat up and a quick cool down in the floor to match our weather conditions.
The difference between our top floor and this bottom floor is the concrete slab. Since I don’t want to place T&G plywood directly on the slab I was considering placing stingers made of trex or a similar product atop the slab with rigid insulation between stringers. The T&G plywood would attach to the stringers and house the radiant tubes.
Before I jump in with both feet, what flags go up or what changes would you recommend?
Replies
The more mass you heat the slower the system will be to swings in outdoor temperature. So, based on what you said I would lean toward not heating the slab. Being in a mild climate I'm surprised you are not going with conventional radiators. Faster and cheaper.
Concrete embedded tubing is not quick response heating, quick trac panel rads are possibly better for you.
Try you Q at heatinghelp.com there are plenty of wetheads over there
My view: sounds like a LOT of expense and material and labor. Sleepers, plywood, finihs flooring. Why not put it in the slab and take that money and invest in a reset controller for the radiant heat? That way you don't have to worry about the lag in the slab. It should always be at the right temp for the outside air temp (largely, anyway).
Acid etch the concrete, seal it, and be done w/ it. Where in Calif?
I'm located in Sonoma County. About 50 miles north of San Francisco.
The way you propose will be a faster response system than an in-slab system, but you'll still be heating the concrete. (Yes, radiant heat does go down too!) If you want to maximize the heat-to-room, vs. heat-to-concrete, you'll need to lay foam over the 'crete, then radiant tubes, then flooring.
Maybe give NTRob a shout out.
Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.
Thanks for the input Mike. You probably didn't get to read the whole post (I was a bit long winded) but I did mention that I would install trex stringers over the concrete with rigid insulation between.From the replys so far I don't hear anyone finding a technical problem with the plan just a concern of added cost and labor.Thanks again.
Well, I read it, but it didn't sink in that you were installling the tubing in the ply that was to be installed over the sleepers/insulation. DOH!
So that oughta work, provided the ply has integral aluminum heat sinks, like QuikTrak or the like.
I've never used Trex for sleepers, tho'. Don't know the coefficient of expansion for Trex, so just make sure it's compatable with the wood subfloor and doesn't expand way more (or less) than the wood when the radiant heats it up.Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.
I would think that someone makes a "system" that provides grooved panels suited for direct install over concrete. Something along the line of the plastic-backed OSB "tiles" that are sold for basement floors.
Whatever you do you want to be aware of the added floor thickness, and be sure to adjust your stairways to match.