How thick must aluminum heat spreaders be?

hot_rod

the aluminum needs to be in good contact with the tube. Just laying pex on aluminum foil doesn't offer a very good "connection" point.

This is a key component in the better extruded heat transfer plates. Not only a very tight connection, but a connection point that stay tight throughtout the thermal expansion and contraction cycles.

This is where the thin "flashing" gauge aluminum plates got their noise and "oil canning" reputation. After a few cycles, or maybe at installation, the tube fit was loose and the expansion noises started. Not to mention the non existent conductive transfer issue.

There may be some reflective value to an aluminum layer under the finished floor, if it stays fairly clean and dust free. Harder said than done when installing flooring on top.

Cutting the aluminum layer on this Warmboard had a substancal effect on the heat spread. The back half of that Warmboard has carpet over it, by the way.

hr

bruce_21

How thick must aluminum heat spreaders be?

I have a customer who is trying to save some money on his heating system. He has in mind to do as much of the work himself as possible. We talked about doing a system like the Watts SubRay where the pipe runs above the subfloor between sleepers with aluminum flashing over the pipe and then his finish floor, in this case 3/4" MDF he plans to paint. He's a carpenter and artist (still life paintings) and will do everything but lay the pipe.

The curve ball here is that he has proposed using the very thin attic radiant barrier insulation http://www.radiantguard.com/index.asp?PageAction=VIEWCATS&Category=2 instead of something like real aluminum roll or flashing. I'm worried it won't spread the heat out and he'll have hot and cold stripes and be unhappy.

Sorry for such a long winded post but does anyone have any experience trying this approach? Dave Yates are you there? Thanks in advance for any insight anyone can share.

Kevin_in_Denver_2

crackly floor

Roll flashing would be crackly underfoot, unless the adhesive is troweled on.

kpc_18

tell him the...

concerns...if he still wants to do it his way get him to sign off. Or you could fire him....kpc

zeke

In addition to the above, the aluminum must have enough thickness to allow lateral conductance thru the thickness to more uniformly dissipate the heat.
I am sure the mfrs have determined the economics of optimum thickness vs the spacing of the piping in contact.
Aluminum foil offers almost zero lateral conductance, so you will get the hot spots as seen in the above IR photo in addition to poor overall transfer of heat.