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Even if you place sleepers on the subfloor and distribute the PEX between them, you’ll still have some ends of the T&G hardwood pieces landing over gypcrete rather than a sleeper. Do you just nail the hardwood only to the sleeprs and let the ends just rest “unattached”? Do you lay more sheets of plywood over the gypcrete and sleepers and then just nail the T&G as you would normally (as long as the nails ddn’t penetrate to the gypcrete? Or should you just blow off the gypcrete approach and attach the PEX under the subfloor using those metal flanges?
The Wirsbo retailer told me the metal flanges don’t conduct heat as well as gypcrete, so you have to run the water at a higher temp. But once the system is up to temp, is that really a big deal? But the Radiantec people recommend using the flange approach. Sure costs less than all that gypcrete and sleepers and extra plywood.
Does the fact that I live where it very rarely freezes (near Portland, OR) make any difference in the efficiency and operation of the gypcrete vs. under-the-subfloor flange system?
Also, the hardwood supplier recommends using quartersawn oak rather than regular oak because the quartersawn supposedly shrinks less on the heated floor. What do you think about that?
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Another option is to use a prefinished T&G engineered wood floor (Harris Tarkett, Kahr's, Award, etc.) and float it (glue the edges) over the gypcrete. It is a more stable wood floor for radiant heat and can even be refinished a time or two if ever needed.
*I've had PEX installed both in gypcrete and stapled up with and without the plates. Homeowners have done nothing but raved regardless of the installation method.In my own home, I ran the tubing (PEX) under the subfloor, stapled up with the proprietary staples, and omitted the plates entirely. I put 1/2 inch foil-faced foamboard insulation, friction-fit, under the tubing, up tight against the staples. In addition, on the first floor (basement ceiling) I put in 6" FG batts.I'm gone from home for several days at a time and turn the heat down while I'm away. I've never noticed anything abnormal in terms of how long it takes to warm the house when getting home.My system runs at about 95 degrees. I'm in New England. Zero complaints. Oil heat, I've used around 900 gallons per year. My house is 3200 sqft.Staple-up application also makes the flooring a snap. Many had warned me regarding wood flooring over radiant, I chickened out and went with a 5-ply laminate, glue down. All seams are still tight, I put in Brazilian Cherry. Still looks pretty nice.As for floating your strip flooring ends over gypcrete, I wouldn't forsee any major problems as long as the ends of the boards are T&G as well. If the ends are not T&G, you may want to put a very slight chamfer on the ends, or round them over, so if one end does "rise" above its mate it won't be as noticeable to the eye or as likely to bury a splinter in your toe. Quartersawn should be more stable. Regardless of what wood you use, allow it to sufficiently stabilize in the house prior to installation.
*Mongo,What are "proprietary staples"? Since those plates are supposed to help disperse the heat, do you think the foi faced insulation effectively take their place? I keep my house warmer than most people (I must be part reptile), so I want to be sure I can be warm enough without higher than necessary energy bills. Should I spring for the cost of the plates AND use the foil faced insulation? Is there one manufacturer you like better than others? I've seen the discussion on making your own manifolds, but we don't want to get into that, so I'll be buying everything. Leaning towards Radiantec now, primarily because the tech support people on their 800 number have been great and you buy directly from them.