OT: under floor heating

EVERY time we have installed in floor heat the tubing was in contact with the floor's surface, in this case the tubing should be placed against the underside of the floor. There are metal reflector panels that can be snapped over the tubing and stapled to the underside of the floor. Better yet is to place the tubing over the sub floor and gyp-crete over the tubing. After all, you are trying to heat the floor aren't you? Why hang the tubing in mid air??

By the way, we just finished laying a small in floor job. 38,000 feet of Rahau tubing! Greg

Check out the under-floor-heating in my house at this URL:

Your actually looking up in the second picture. You can see I stapled the tubing every 3 feet, plus the snap on reflectors that are all the way around the perimeter of the house. The tubing should have been staple every 1.5 feet due to the fact it has sagged over the 5 years that it has been installed. Makes for a very warm floor in winter.

B

I have never seen it done that way around here. What if you install hardwood floors and the nails or staples hit your tubing. The overpour method also eliminates the possibility of ever having hardwood floors.

Seems to me you'd have an air gap that would reduce condution of heat. Granted it would warm the air in the space, and warmer air would rise. Question is whether the tubing sheds enough heat to the airspace before completing a circulation loop. Of course, wood isn't that good of a thermal condutor either.

Some thought is required when nailing down wood flooring but it can be done. There is a method that lays strips of wood over the sub floor and the tubing is run in-between the strips. The finished wood flooring gets nailed to the strips. There are many ways of doing it, but hanging the tubing in mid air, below the floor is not right anywhere! Greg

Agreed. But, can he maybe get some benefit by fitting sheetmetal reflectors below the tubing? It'll get the radiant heat transfer, but he's still losing the conductive transfer.

Any heat it sheds will rise. I don't think reflectors would help much. Might be a small benefit from additional heat transfer area.

Well, you have radiant heat transfer, conductive heat transfer, and convective heat transfer. Heat rising is "convective" - the air around the tubing gets warm and floats up to the floor. The radiant heat, however, unless reflected up, will go (radially) away from the tubing, half of it going down where you don't want it. A reflector will send it back up. You're literally reflecting the infrared light (heat) coming from the hot tubing at that point, rather than letting it go into the basement.

Me, I'd get ahold of the guy who mis-installed the product, educate him that he did it disturbingly wrong, and ask for compensation. For varying meanings of the word "ask for".

Dave Hinz

(thinks)

OK, that'll absorb the radiant heat, and then allow it to convect back up to the floor. So, yeah, it'll help. Still not as good as you'd have with it properly installed, but better than it is now.

That might be true, but there are some serious heat transfer problems with that approach.

At this point, it's a reasonable approach. I don't think you'll get any more heat transfer without physical contact by any other method.