Radiant floor heating question

Joe_49

I'm planning on building a small bathroom on the top floor of my house and want it to have a warm tile floor. Is there any reason I can't remove the existing flooring to the joists and run one 3/4" copper pipe between each joist about 2" under the new sub flooring with insulation under that? I'll add a section of baseboard radiator and "balance" valves with separate control of the flow of water through the baseboard and piping under the floor. This whole thing will be connected directly to the existing forced HW heating system. The temperature of the water is controled by the outdoor temperature and could reach 180 deg. I can't imagine over heating the floor since heating pipes are run under the floor all the time. I remember as a child living in a house where the hot water pipe to the bath room ran under a spot next to the sink and how nice and warm the floor felt in this area after a shower.

I've always wondered why I've never seen this kind of radiant floor heating before. Radiant floor heating with separate pumps and controls make sense for a cement slab, but why go to all the expense and risk driving a nail into it on an above grade floor?

hr

Sure you could

That is basically a suspended tube application. Usually done with pex, but years ago they were done with copper, just as you mention.

I wouldn't allow the tube to touch the subfloor when running that hot, it could stress the wood. Wood manufactures start to cringe at around 140°constant temperature against wood.

Plan for some expansion movement and use plastic clips rated for that temperature to mount the copper.

You could use bare BB element for a bit more output, along the lines of the Ultra Fin product.

It may provide enough heat to not need the baseboard in the room.

Use the Wirsbo suspended tube output charts for a rough guideline on output, although the copper pipe will be a better heat transfer tube.

Copper is a conductor, plastic is an insulator

hot rod

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Dale

Small

If the room is small I would look into radiant elect matt under tile, with available setback stat you could warm the tile only when you were there. If you put a cast iron tub in a length of baseboard behind the tub warms all that cast iron.