I will be building a new shop next summer in the lower midwest. It will need heat throughout the winter. After reading this forum for a while, it seems that radiant floor heat may be a good way to go since I haven’t built yet.
My question is: Does it only work installed into the concrete floor or will it work installed into a raised 4″ plywood floor later on? Not too sure. Thanks.
Replies
Dear Box,
That will be very inefficient as the air gap will insulate instead of transmit the heat. Why the raised floor?
John
It can be installed as part of the plywood floor, it shouldn't be installed in the slab if the concrete will have a wood floor on sleepers over it.
John W.
I installed a two zone closed loop radiant heat system in my shop this past year and I can tell you that it is the absolute best thing that I could have done. I did not have the option of installing the pex in concrete. On my plywood subfloor I installed 2x2 sleepers and ran the tubing (3/4" ) between the sleepers . After the tubing was installed I poured sand over the Pex as a thermal mass. I then put plywood over the whole thing (get the sand off of the sleepers) and connected to a 100000 btu propane water heater. Having the system running since October I have spent less than $300 on propane , and the shop (24 x 36 ) and second floor office (24 X 24 ) has been kept between 65 and 70 degrees. I am located in central Pennsylvania .
If you would like more technical assistance I can give it a try or direct you to some helpful websites.
BTW I installed the whole system with only a small amount of plumbing experience.
John S
Nothing so comfy as a warm floor!!
Not only is the floor warm the whole shop is a consistant temperature with no drafts.
jcs
I'm glad to hear about your system. I have two buildings with radiant heat. One is a slab and the other, my home, is a plywood subfloor then PEX, covered with gypcrete, then hardwood floor. Both my home and shop are wonderful systems. At the house, I contemplated doing the sand cover but went for the more conventional (at least here abouts) gypcrete. I always figured the sand would work well and now you've confirmed it.For the subject system of this thread......I would not hesitate to install a similiar system to jcs'. Lay the pex tubing into that 4" space and cover with sand. Then install whatever floorcovering desired.
There are reflective, insulated panels that can be laid in first. I plan on using it for my floor instillation. Its a product from the plant propagation industry. Its two sheets of foil backed 3/8 bubble wrap with the bubble sides glued face to face.The only question I have is how did you secure the tubing to the old cocreate floor? Do you feel that the tubing needed to be secured in place on the long straight runs for a sand installationDid you use a vapor barrier? Ron, Mass.
Well, neither of my installations required fastening pex to an existing concrete floor. The first has the tubing imbeded in the slab. There the tubes are tied to the reinforcing mesh prior to placing the concrete. The other install is over a plywood subfloor laid on wood joists (typical home construction). The pex there is stapled to the plywood, then gypcrete is placed/pumped over and allowed to harden. I reckon that fastening your tubing to a concrete slab could be best accomplished with a powder actuated fastening gun.... a Ramset. This would be fast and effective. The pex is a bit unwieldy......no, it is a lot unwieldy......fastening it down prior to placing the sand will save your sanity. In concrete or gypcrete installations, fastening or anchoring is necessary because the air filled tubing will want to float to the surface and that would be unfortunate. With sand, floating isn't an issue, but tripping over it, kicking it out of position, etc. will be. You could anchor the tubing with sand as you laid it out, but that technique would make a pressure test difficult. Actually the test isn't made difficult but if you get a leak, finding and repairing the leak is really hard. Personally, I'd use a ramset and anchor enough to keep the tubes in place. You can find a lot of info on the internet. http://www.radiantdesigninstitute.com is a good place to start. There are also lot's of discussions on Breaktime.Jeff
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