Radiant heat diffuser material


Old 12-20-11, 12:50 PM
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Question Radiant heat diffuser material

I'm in the process of building a house and want to put in a radiant system. Money is tight - very tight so I'm looking for ways to save a few bucks. I'm wondering if the heat diffusers need to be made of aluminum. I work driving an Amish pole barn crew so I can get left overs/scraps of the flat metal trim from the installs for free.

Can these pieces of metal, called galvalum, be use for diffusing the heat from the pex tubing or does the diffuser need to be aluminum?
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Old 12-20-11, 03:23 PM
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Aluminum will conduct heat at least 8x more than steel. Coated steel is an unknown.

If you were going to go through the effort of making diffusers I would use aluminum flashing.

Nothing is going to compare to the panels made for the purpose.

If money is that tight, investing in more insulation below the tubing may be a better route. You'd need the calcs to see if it would actually work based on your design conditions.
Old 12-20-11, 03:54 PM
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I tend to agree with Tim, that now is not the time to compromise the install, although I'm sure it would work. On the technical side, the heat will travel slower through the steel than Aluminum, however, it then must heat up the wood and wait for the heat to pass through what is essentially an insulator, before more heat can flow from the source to the outer edges of the steel. In other words, the heat only has to move through the steel fast enough to keep up with the heat moving through the wood, it doesn't have to move as fast as it would through AL.

If the space below is also being heated then any heat that escapes below is still doing some good. But if the space below is not intentionally heated, LOTS of insulation and a rigid air tight covering like sheetrock.

Old 12-20-11, 05:06 PM
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This stuff is probably way over the OP's budget, but it sure looks interesting.
4' High Performance FlexPlate for 1/2 in. PEX - 20 pc | Pexheat.com

Old 12-20-11, 07:37 PM
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Hi Peter, I think the important aspect of that product is its ability to get the heat out of the pex and over to the floor where it can do some good. The maximum contact area would be hard to replicate from scraps. But how much he needs to transfer per foot is all part of the calculations which haven't been mentioned as yet.

Mr10, did you do a heat loss for the area being heated and size that to the pex?


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