Bending pex?

Kevin O. Pulver

You can heat it with a heat gun and it will stay where you cool it. But I don't think that is the answer to your problem. Very hot water might make it lose the shape you wanted. The metal bend supports, copper stub ells, or something else might be the fix. There are nice fittings available, and if you find what you need, you'll appreciate not running copper everywhere. Kevin

Jim Franklin_2

Bending pex?

I'm using Wirsbo HePex to run between baseboards on a new system. I soldered the nice expensive brass ProPex 90s onto each baseboard before realizing how stiff the Pex is. Trying to route and secure this stuff will have the baseboard flopping around like a broken air hose.

Is there a way to soften it to bend it? If so, will it maintain its shape when it cools, or try and go back to the coil shape it was shipped in? Should've stuck with copper...

jim

Wayco Wayne_2

I use the

metal braces that hold the pex at a 90 degree angle. Latey I use Multicore tubing, or PAP tubing. It holds the bends no problem. WW

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Weezbo

silver shiney 90's ....

like Wayne says:) or pump a innie into a baseboard T, shove the tube down a ways and pump it onto the innie.or take a pls or pro pex 90 and pump it onthe riser and straight shot to a innie or outie already sweat in place..

Scott Gregg

There are ploy braces too.

I like the poly ones with the nail plate. Lets you bend it and secure it with one peice.

Jim Franklin_2

Poly stronger than steel?

I grabbed some of the steel braces. They work great except in tight spots, as I'm threading the pex up into a hole, forced the brace to open up and bent it. Are the poly ones stronger than the steel ones?

Still on the fence about pex vs copper, especially after having to make a lunch run to get the expansion fitting rings no one told me about :-)

thanks,
jim

[Deleted User]

The key to using PEX for high temp applications...

is understanding the fantastic growth potentials, and knowing how to control it.

PEX expands at a rate that MUST be accomodated in the design of the system, if not, it will bind up against the structure and transmit some of the strangest sounds you've ever heard from a piping system.

If the tubing is not locked and the growth pootential sent to a safe haven, it will expand where IT wants to and in the direction it wants to, which is probably not a safe haven for expansion.

Safe havens for expansion growth can be as simple as locking the tube down on one end, leaving clearance on the other end and lettin' er rip. As the tube heats and expands, the growth it taken up without binding the tube. The end of the tube floats freely without binding and sending the growth in another direction. Growth accomodated and controlled.

On longer runs with greater growth potential, the tube can be "locked" on both ends, and a loop de loop installed in the middle. As the tube expands, it grows towards the loop, which gets larger and smaller in diameter depending upon wether its expanding or contracting.

Speaking of contraction, don't forget to accomodate your long snowmelt runs for some major CONTRACTION...

It shrinks at the same rate it expands, and not leaving enough "slack" in the lines can result in lines shrinking so much that they cause major disconnection from the building to which they were hung. I once crawled back into a crawl space that was holding a small snowmelt boiler. The 1-1/4" PEX supply and return lines were laying on the floor of the crawl space. THey had pulled the Sioux Chief plastic talons away from the structure. Ripped right through from the stress of the tube SHRINKING in length...

I know, because I was the knuckled head who had installed it the summer before... Leave it some controlled slack.

PEX's co efficient of expansion is 1.1" per 100 foot of tube per 10 degree F change in temperature.

That means a 100 foot run will expand by almost 8" (tube going from 70 to 180). Realize of course that each change of direction breaks up the growth potential, but it's all still there, all 8"s worth. And if you don't accomodate it, it will be noisy. "Tis the nature if the beast"...

A tube lock can be as simplie as a hole in a 4" long 2X4, on the flat side, in the middle middle. THen saw the 2X4 length wise, through the center of the hole. Place each half over the tube, holding it against the joist tighly, then run screws throught he short side of the cut to "clamp" the wood onto the tubing, then screw it flat to the floor joist, and VIOLA, you've got a "tube lock". The tubing HAS to expand away from that point. Accomodate it in either or both directions will result in a trouble free, virtually silent piping system.

Pure comfort is NOT being aware of your surroundings. If you can HEAR your heating system, you're aware of your surroundings. In other words, you're NOT comfortable...

Questions? Comments??

ME

Jim Franklin_2

Holy expanding pex, batman!

Thanks for pointing that out Mark. I looked for that and similar info all over Wirsbo's various websites but they are like vacuous prom queens (all glitter, no substance). Some googling turned up the installation handbook right here on HH. Looks like I can still add in some expansion factor to the stuff I ran last night, and I'll lock down the end at the baseboard so it doesn't move the element around.

jim

hr

Good points ME

I did a snowmelt tube job on a ninty degree day. The next morning the pex was as tight as guitar strings!

Never ever put ties on the apex of the pex at the bends! The ties could actually cut into the pex when it cools and contracts.

Switch to PAP and these issues all but go bye bye.

hot rod

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Tim Doran

Tech Support

Have you tried calling Technical Services to have your questions answered? (952-997-7900)All of the information exists on our web site in a secured area that all Home Comfort Trained contractors have access to. Have you had any local training, has any training been offered?

Tim D.

Tim Doran

Pipe size considerations

Choosing the smallest practicle size that will support the load is also a big help. It is not always nessessary to run 3/4" tube. Considering a home run method is another option that allows zoning flexability and the use of small tube.

Tim D.

Jim Franklin_2

Thanks Tim

for responding...I didn't call anyone. I get much better info here. Most times when I call a manufacturer's "tech support" line I get someone with a 3rd grade reading level and raging hemorrhoids- it's not worth it to try anymore. I realize I dove into this blind, but the website could specify that there's assistance available for the overambitious folks who don't work with the stuff often enough to take training.

Regarding sizing, yea the 3/4" was overkill, probably by a factor of two as the informative counter guy at Peabody Supply told me. But had there been info like pressure drop tables on the website, I could have chosen my sizes more accurately. At least I can use really small circulators now :-)

jim