[VAC] Re: Balsa core flooring

[rlb <blammo@xxxxxxxxxxxxxx>]

"Dr. Gerald N. Johnson, electrical engineer" wrote:

> I believe that the modern radiant floor heating is based on 120°F water,
> not 180 and that the PEX is not rated for continuous use at 180.
> Certainly that may be a warm temperature for the foam.

I always get confused about the temperature difference between BaseBoard and
Radiant floor. I have baseboard in my home, and plan on using radiant for my
addition and eventually replacing the baseboard with same. I need to use a
mixing valve for the lower temp radiant floor.

> Why not Formica for the top skin? It could be a maple block pattern, or
> green marble or many others. Its strong, can be the finished surface and
> stands heat and other abuse.

I was trying to think of something that would be able to stand up under the
pressure of say a high heel shoe, or similar. I think the masonite might be the
best, but aluminum might work also.

> If the foam was the same thickness as the tubing diameter, it would be
> more productive to rip the foam into planks with a table saw

I was thinking about the ability to be able to run the tubing exactly where
desired and at differing spacing, the routing process would leave all option
open.

> than to
> route it for tubing. The end turn regions would need to be routed.

I also like the idea of having to press the tubing into place to restrict
movement and also to stabilize dissipation plates that could be installed under
and around the PEX tubing and still lay flat on top of the foam.

> Thinking about materials that are relatively easy to find, Menards
> carries a fiberglass laminate panel for about $24 a 4x8 sheet. Most
> every building store carries 1/2, 3/4, and thicker Dow blue board. Bead
> board is not suitable. The only rub I know of for Formica (or
> Wilsonarte) is that its sheets tend to be only 30" wide.

I'm not a big fan of this stuff, seems brittle, but maybe that's because I've
only seen it with age.

> The adhesive of choice is probably water based contact cement, I know it
> sticks dow foam well. There are probably some epoxies or polyester
> resins that would work well. Solvent based contact cement will not work
> with the foam, it disintegrates the foam on contact before the contact
> cement can dry.
>
> The lower skin needs to be a material strong in tension. Aluminum sheet
> would work if its glued well. Its a bit harder to glue than wood or
> scrap masonite.
>
> Its a bit hard to insert tubing into a factory made panel though factory
> panels can be inspiration for home made panels.
>
> An alternative assembly might involve foaming after assembly.

I think this would be a major undertaking. I like the idea of using whalers for
restricting the expansion of the panel while under foam pressure though.

> E.g.
> spreading the tubing around the bottom sheet, then dropping on a top
> sheet onto spacers with enough through fasteners to withstand the
> pressure of the foam and some holes in one face or the other to allow
> both squirting in foam and pressure relief. The through fasteners could
> be removed after the foam had set and those holes filled with foam too.
> Or the assembly could be held between two flat platen plates (might be
> braced panels like concrete basement wall forms) and the foam squirted
> in. This way the tubing would be anchored more tightly and would release
> its heat a bit better than when kind of loose in rigid foam.
>
> There are far more solutions that problem.
>
> The insulation in the middle makes the foam with double aluminum facing
> poor for putting the radiant tubing on the bottom of the assembly.
> Aluminum conducts heat to the sides better than the insulation conducts
> it through.
>
> Aluminum as a top sheet on a home made panel would serve well to spread
> the heat and to make a uniform surface. I'd consider a break in the
> aluminum skin at the cabinets and the cabinets and not put heat plumbing
> under those because they don't need warming, but the occupants do and
> can only feel the heat that's not covered by cabinets.

Since I tend to over build everything, I'm going to disagree with you here. I
would however use larger spacing under the cabinets and also use it as the
return run back to the heat source, so that the heat output would be maximized
into the living quarters

> I'd put a thermal
> break in the aluminum skin so the aluminum didn't conduct heat there
> either.
>
> I still think Masonite may be the optimum upper surface.

Somehow I can't get rid of the idea of a metal upper surface, mostly based on
the heat transfer capabilities.

What are your thoughts on a heat source?

bobb