Which construction yields the most efficient radiant system? The market has a couple of new products that seem very attractive to me, namely an aluminum clad tongue and groove subfloor pre-grooved for pex. This product supposedly only requires a 100 degree boiler temperature as opposed as the 125 degree boiler temp in a gypcrete/concrete scenario to acheive the same room temp, but this product also has no heat retention–so although a boiler wouldn’t be working as hard, it would be working more constantly. This product also responds more immediately to thermostats and requires one less subcontractor……How does this boiler temp versus heat retention issue boil down?
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I've also looked at the combined subfloor and radiant panels, but have a hard time justifying the cost (I was quoted $4.50 per square foot). As far as the system running more often, several articles I have read recently advocate a system which runs water through the tubing continuously, varying the temperature of the water to maintain the correct temperature. The claim is that this provides a more even temperature and is more efficient. I am not vouching for this being true, just passing the info along.
Is that $4.50 per sq. foot just for the subfloor?
Yes, that is the price quoted for warmboard by the local distributor. Material only for their subfloor.
yeah, that's the price of the subfloor, although for that price they map out your whole system, so you don't need a radiant specialist to prescribe and run your tubing, and there's also the fact that you're not dealing with gypcrete, which I've found to be a bit of a mess...
Hi-mass vs lo-mass systems can get as contentious as any this vs that discussion. One can make a case for either. I happen to fall on the Hi-mass side of the divide--I like a floor that I can get warm, and it will stay warm with the heat off or on. I use 115 degree water. Warmboard is somewhere in the neighborhood you mention, but that prices out near a subfloor/gypcrete assembly. Each can work. No single right answer.
thanks. I guess what attracts me to this warmboard is having one less sub, and I don't know what your experience has been, but prepping for the gypcrete guy is another whole ball of wax....anyway, thanks for your thoughts.
I doubt I would do gypcrete again. I also doubt I would spec it for one of my clients. I understand its use in apartments and such as a sound and fire barrier. For me it's been as much pain as benefit, and most of the pain has been when installing the flooring over it.
Did you do gypcrete in your dome?
Were you allowed to glue the bamboo directly to the gypcrete? If so, did you have to prep the gypcrete at all?
For some reason I thought you did a standard slab.
One of each, Mongo. Well, two slabs and one gypcrete. Top floor is tji's and we did gypcrete on that for heating purposes. It does help muffle sound from above, but that's the most good I have to say. The thermal qualities pale compared to the hi-mass, and the responsiveness is crappy compared to the lo-mass.
No prep of floor prior to gluedown, per gypcrete installer. Here's hoping they knew what they were telling me. I was specific on what I intended to put on that floor. For the tiled areas, did use anti-fracture membrane.
If doing again, since I built a duct chase around the perimeter, I'd likely use warmboard in the field (the duct chase squared the walls), and ply or nothing in the duct chase. Well, ply for firestop reasons. With our structure and floorplan, the RFH in the main slab has been enough to keep the upstairs about 69 on all but a few winter nights. For those nights, the quick response would be better.
Thanks for the feedback. I think with the increase in effective product coming to market dedicated to lo-mass systems, you're going to see less gypcrete and more of the Warmboard-type of construction.
I've heard good and bad about glueing directly over gypcrete. The last thing any of us needs to go bad is a glue-down floor install. What a pain that would be.
I appreciate RFH ever time I visit non-RFH houses. The difference in comfort is amazing.
Thanks for the info.
Since I am getting ready to install a gyp crete radiant floor I would be interested in the problems you have had. Thanks in advance