Pex Tubing

Weezbo

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Dorsey Davis

Pex Tubing

I've been running into problems with pex tubing moving, 'clicking' etc. I understand that installing Pex AL type tubing eliminates the problem on a staple-up but that you have to use 3/8". Is there a type of tubing other than AL Pex to use on staple-up jobs so that I can use 1/2"?
Also, with floor panels such as Roth Panels, how do you allow for tubing expansion?

Unknown

why 3/8 only?

Dorsey,

Why only 3/8 on Pex-Al-Pex? I've used 1/2 before.

Why not try Watts Onyx? Proven product. Cross linked rubber. Great for dry application.

Roth Floor Product is avaialble for 3/8 (1/2OD) and 1/2 (5/8OD) PEX. I love the product.

GH

Radiant PEX

I WOULD NOT RECOMMEND STAPLE UP JUST FOR THE REASON YOU
MENTIONED . YOU WILL FIND THAT STAPLE UP NEEDS SO MUCH
HEAT TO GET THE JOB DONE THAT THE TUBE IS ON THE BRINK OF
ITS DESIGN.YOU MIGHT WANT TO CONSIDER DOING RADIANT THE
WAY IT WORKS BEST AND MOST EFFICIENT . THAT WOULD BE PUTTING A THERMO MASS IN THE LIVING SPACE.

cruizer

The clicking you hear is the outer layer oxygen barrier (EVOH) of the PEX rubbing on whatever it is contacting during it's expansion and contration. The EVOH layer has a high coeficcient of friction, therefore sausing it to "stick and pop." PEX-AL-PEX has no EVOH barrier. The outer later is PEX, which has a low coeffieient of friction. The aluminum in the interior serves as the oxygen barrier. The aluminum is in the center, also, to help protect it from the elements, therefore never getting damaged. Why companies put the EVOH barrier on the outside is beyond me. Defeats the purpose when it get's scraped and torn off.

Anyways, most companies, places, contractos will specify 1/2" tubing for staple up. Never heard of only using 3/8's." I try and talk people into using 1/2", 3/8's will have high head losses due to is't small size and the high temperature needed for the below floor application. This will reasult in alot of short loops. You'll waste alot of money in fittings and manifolds.

wetheat1_2

EVOH

Just an FYI. Some barrier pex products have a protective skin over the evoh. It also helps reduce noise as it has a low drag coefficient. Most noise issues are due to extreme expansion and contraction resulting from one temperature systems. Good control strategies that include the use of reset are key to noise reduction. Just curious, what does high temperature have to do with head loss?

Tim D.

Unknown

pex etc

Cruizer,

EVOH barrier does make tube "squeek" more then non-barrier pex....but the major comtributing factor is IMPROPER installation!!! Pex expands 10 times more then copper or pex-al-pex, hence the reason the staple up jobs are made to be able to float and expand (and also the reason for only fastening every 3-4ft).

Pex/al/pex doesn't squeek because the expansion coefficient is near to copper.

The reason the EVOH barrier is on the OUTSIDE is because (A) it is nearly impossible to put it on the inside, (b) if you spray the EVOH on the outside the same tube process can be used for heating and plumbing, (c) the inexpensive EVOH does not hold up well to constant submersion in water, (d) you can scrape of ALOT (just over 2%) of EVOH and still meet DIN O2 ratings, (e) ALL THE ABOVE.

Size of tube WILL effect head and flow but probably not temperature required.

Still the BEST tube out there (if you have an unlimited budget) is Alu-Pex, which is a full ASTM Pex Tube with a LASER welded seam (not overlap and glue) outer Aluminum wrap with a protective plastic spray coating on top.

Regards,

Steve

Unknown

Panel products are made to limit the ability of PEX to expand in the first place. However, we prefer to use PAP above the floor. Not much harder to work with there and it does give that peace of mind.

Howeverr, under the floor, I personally wouldn't want to install PAP (though others do). We use controls that vary temperature slowly, and that operate the system in as close to "steady state" as possible to limit expansion that way. And we don't have noise. Make sure to give the tubing places to expand there though!

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