Radiant Floor install qestions

Ron Conrad

I am 2 months into building my home. We are installing radiant floor heat (PEX in 1.5" gypcrete on top of subloor). I plan to put in 3/4" tonge & groove conventional hardwood floors. We plan to install 2"x2" sleepers to attach the hardwood. We live in Yakima, WA 98901. Our average winter temp is in the 30's. Lots of western exposure glass. System is a Polaris boiler with a Weil Mclain hot water heat exchanger.

Question #1 what is the proper spacing of the tubing. Should I run the sleepers over the floor joists(16" on center) then run the the tubing through the 16" space twice or is just once through there enough. Or should I not worry about being on top of the joists and run the nailing sleepers at a different width?

Question #2 what is the maximum temp I should run the water at to not get the floor above the recommended 85 deg F as not to damage the wood?

Question #3 The plan is to run the floor heat off the boiler and the potable system off the heat exchanger tank. BUT can I do the opposite so I can get hotter water for use in the potable system.?

I have not purchased the heat exchanger yet so I am also open to any better options.

ron.conrad@charter.net

hr

A true design

would answer all your questions regarding tube spacing, supply temperature, loop length, and pump spec. Anyway to have a heat loss calc and design done for you?

Consider 2X4's for your sleepers. Much better nailing surface, and easier to glue and screw down without splitting. Make sure you use construction adhesive, on a clean and dry floor, and screws to keep those sleepers from squeaking and moving as they dry out after the gyp is poured against them. Nothing worse than a noisey hardwood floor

You will need to decide which way the final wood flooring will run to place the 2X4's. They may run with, or against, the direction of the floor joist. Either will work.

Sure you won't consider a floating engineered flooring. A much better match for radiant and gyp, I feel. Takes the whole sleeper hassle out of the equasion. Hard to get a real nice gyp pour between the sleepers. Seems it always shrinks down a bit then the gyp does not contact the flooring for a good conductive transfer.

It's also hard to get a bundle of nice straight 2 bys for the furring strips

hot rod

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Unknown

a few things

1. Run the sleepers opposite the direction you want to run the hardwood. You want 12" o.c. or tighter under hardwood, 9" o.c. or less being best typically.

2. The maximum temp for concrete is 140 deg F. supply water temperature. However, to get the floor surface area temp required, a heat load calculation would need to be done.

3. Use a brazed plate heat exchanger instead of a second tank. Take potable out of the polaris and heating water through the exchanger. The second tank should be pretty unnecessary. You'll need a tempering valve for the domestic to prevent scalding issues.
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Northeast Radiant Technology, LLC

Robert Brown, Co-Owner, RPA certified Radiant Designer

207.899.2328
NRT@maine.rr.com

[Deleted User]

I run my sleepers with the floor joist . I also seal my subfloor and sleepers with a water sealer like tompsons to help stop the shrinking problem