Radiant Bathtub?

heretic

A number of folks have mentioned in prior posts that creating a 'radiant bathtub' is a popular bonus for their clients when installing infloor radiant. A big cast iron radiator, right? Why not...
A great idea, but none of those posts are recent enough to show in the Search.

Are there any special tips or techniques to doing this?
What is the best way to secure the PEX to the underside of the tub?
How much tubing needs to be in contact to get a good effect?
How should the tub tubing be layed out relative to the floor tubing?

hot_rod

If you

have high temperature available a strip of baseboard element works well. On low temperature radiant Watts Onix works great.

On cast iron tubs I have used construction adhesive and glued the tube against the side of the tub. Besure to insulate between the tub and outside wall, of course.

PAP would be another method to try. It may stay against the tube with fiberglass insulation jammed against it.

hot rod

heretic

Thanks

As you say, perhaps high temp would be better and easier for this application.

heretic

Adhesives

Any concerns about using adhesives on PEX?

hot_rod

I've

got a thumbs up on using silicon with pex from several manufactures. Never could get an OK for Liquid Nail or other adhesive products, however. Probably depends a lot on the chemical make up of the adhesive you are considering.

I have used Liquid Nail with the Onix product on a glue down to a concrete slab for an overpour, with permission from the manufacture. The construction adhesives have a lot more "hold" than silicone and tend to set up much quicker. I think.

hot rod

heretic

EPDM

Oh, I see what you mean.
Onix is EPDM, which is very resistent to solvents, and has multiple (sacrificial) layers besides.
Also rated for high-temp. Interesting stuff...

Thanks again!

Don in Albuquerque

PEX vis-a-vis tape

In Dan's "Hydronic Radiant Heating", page 118, he warns against using tape on PEX tubing, saying "the chemicals in the glue don't get along well with PEX."

I've begun selling closed-cell polyethylene insulation, and Dan's warning worries me regarding tape adhesive etching or eating the PE insulation. There is a variety of tape adhesives, including acrylic and rubber-based. And Intertape AC50 SP is a spray adhesive, "specially designed to bond polyethylene to itself, as well as wood, concrete and other surfaces. Does not contain methylene chloride."

Can anyone here speak from experience, in applying adhesives to PEX on any of the above surfaces, including bathtubs?

Art Pittaway_2

Fin tube..?

Hey, H.R., I thought you would have told him to drop a piece of bare fin tube between the tub and front and let it heat things up. I've got a book from the fifties somewhere that shows that trick. Also shows radiant with screwed pipe. Oh boy! To much fun at ASHRAE today...!
Art

heretic

Chemical Resistance

Regarding chemical resistance of various tubing materials, I found this link interesting:

http://www.ipexinc.com/download/pdf/IPEX_ChemResGuide.pdf

Warmfoot

Bathtub tubing

Here is a custom tub we did last year....Unfortunately, I have yet to make it back to take final pictures....

Ernie Bogue
Master Hydronics LLC
PO Box 779
Keyport, WA 98345
(360) 394-2049

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