Radiant Heat PEX Bending

Countryhouse

I'm installing radiant heat floors in my kitchen and bath and have a question that I haven't found an answer to (even after reading hundreds of pages on the net).

The instructions for most PEX give a bend radius for bending with the coil direction and another bend radius against the coil direction. For example, my 3/8" PEX says a bend radius of 4" with the coil and 12" against. The bend radius is much larger against the coil direction.

The typical PEX installation that are shown show back-and-forth loops at each end of the run, which means the bends alternate direction every loop. Also, it's not really practical in most cases to keep all bends in the coil direction only.

How do you keep the tight bend radius at each loop that is "against the coil direction"? Do you twist the tube 180 degrees along the straight run so that the bend directions are all with the coil direction?

Thanks in Advance
Steve

Alan(CaliforniaRadiant)Forbes_4

It seems

as though it naturally works out that way. I've never had to worry about it. The tubing will orient itself to make the easiest bend.

Paul Pollets

Radius

Especially if the tubing is coming off an uncoiler. We keep our loops as tight as 6" by either staples or nylon ties.

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[Deleted User]

The Cork Screw principle...

Have you ever pulled tubing off of an uncoiler and TRIED to keep it from cork screwing on you? I don't think it can be done without breaking your wrists.

Not to worry. In all the 30 plus years of doing this, I've NEVER had to fight the tubing (any more than usual) to get it in to a tight radius bend. Me thinks you're over thinking it. Quit reading the web and get to work installing tubing... It will go a lot smoother than is has been in your dreams (nightmares?) .

ME

Jeremy_14

3/8\" really?

Being new to hvac 12 years ago, my boss told me to install a radiant heat system with 3/4" pex. Six hundred feet later, I switched to 1/2" pex and told my boss to go... Needless to say, I understood almost every radiant install trick in the book after that miserable job. Steve, like the previous poster said, me thinks your overthinking it.

klaus

I wonder if your using pex-b or pex-a. Most of the pex-b I have come across is quite stiff, but pex-a (Mr.Pex is what I have used)in comparison is very easy to bend both with and against the coil.

Leo G_102

All our manufactures

up here in the frozen north, just say that the smallest bend allowable is 20 times the diameter. Therefore 1/2 would be min. 10 inches.