PEX Fittings: Which Type Is the Most Freeze Tolerant?

Tom_22

It's well known that PEX pipe is better than most (all?) rigid for ability to tolerate freezing without failure; but I haven't heard much about which fittings offer the best freeze tolerance.

Is brass or plastic better? And if plastic, is there a preference between the types? Apparently, there are several different types of plastic.

The application is a vented, uninsulated crawlspace high atop a Pocono Mountain in Northeastern Pennsylvania.


I realize ideally one would eliminate the use of fittings altogether in the crawlspace, but this is a retrofit of a previously foreclosed upon property, and some hookups will be to existing copper pipes stubbing through the first floor into the crawlspace. The crawlspace main is missing. Apparently, stealing copper pipe from empty homes and scrapping it is a popular activity around the Poconos.

SWEI

PEX pipe will survive a certain amount of freezing, but regular freeze-thaw cycles will bulge it beyond hope. PEX-a is a bit tougher that the rest.

No PEX fittings that I am aware of are truly freeze resistant. They must be made out of very rigid material in order to seal to the pipe. You freeze them, they explode.

Aquatherm (thermally welded coextruded polypropylene) tolerates a bit more freeze-thaw than PEX does, and the fittings are made out of the same resin as the pipe. I still wouldn't spec it for that kind of location without a heat trace tape or some kind of water temp control/safety system.

Jamie Hall

or glycol... much as I know that it's a pain in the ... neck.

Tom_22

I'm not planning on letting the PEX piping and fittings freeze. I will insulate it, and close the crawlspace vents, and I may heat trace it if I can get an idea from any locals if they recommend it for those conditions around there.

I was just wondering if it did freeze, despite whatever reasonable steps I take to prevent it, if there was a marked preference for brass or plastic.

Asking around a little bit since I posed the question here, I got a couple of opinions that if anything, plastic was preferable to brass for freeze resistance.

hot_rod

The copper pex fittings would be the softest and most freeze tolerant, probably. Sioux Chief and others offer them.

Larry Weingarten

Hello: NREL did some freeze testing of PEX with brass and plastic fittings. The plastic held up better as it lost heat at around the same rate as the pipe. With brass fittings, they freeze quickly, trapping freezing water in the pipe, forcing a burst. Damage happened in pipe that was pretty short, between fittings. Hope that helps!

Yours, Larry

kcopp

From my experience I have never seen a fitting freeze failure on pex due to freezing. I have see a fair share of splits on pex tubing from PexA to pexC. The pex A tended to fail right next to the fitting where the B&C tended to fail further away.

Bob Bona_4

One would hope the nearby pex would take up the expansion, I guess all bets are off if that one fitting is extremely exposed

ChrisJ

Regarding the pex taking up the expansion, I thought only pex a claimed this? I've never seen pex b or c claim they tolerated freezing.

Speaking as an amateur, pex a with the expansion tool is the only pex I'd consider using in my home.

Dave H_2

The fittings are not the weak point in a freeze situation. The tubing is going to be the weak point. Not that I am saying the pex is weak by no means.
My suggestion is to go with what is most common and what you can get on the shelves at the local wholesaler.

Dave H.

kcopp

The best tubing I ever saw for freeze tolerance was actually Poly Butylene. I saw an entire house freeze up one January and the only breaks were on a the heating system... the water was 100 w/ the exception of the shower valve drop ear 90 that popped off the riser.

hot_rod

Tube expands a lot, the next fail point is the fittings squirt off the tube, same with SharkBites in a hard freeze. Fittings breaking are the last failure typically

MaxMercy

Tom_22 said:

I'm not planning on letting the PEX piping and fittings freeze. I will insulate it, and close the crawlspace vents, and I may heat trace it if I can get an idea from any locals if they recommend it for those conditions around there.

When insulating any pipe, leave the side open to the area less likely to freeze - so if in a crawlspace, insulate beneath the pipe and leave the top exposed to the living area (less likely to freeze or at least freeze last).

Larry Weingarten

Hi @kwalsh , J Burch did a number of reports on freezing pipe before he retired. We're both taking info and different perspectives from the same author. In the report I was looking at seven years ago, he was looking at how freezing was initiated and how it progressed. As HR says, it was tubing that failed. I don't think we have much, if anything to disagree about. We're just checking out different parts of the elephant.

Yours, Larry

hot_rod

Larry Weingarten said:

Hi @kwalsh , J Burch did a number of reports on freezing pipe before he retired. We're both taking info and different perspectives from the same author. In the report I was looking at seven years ago, he was looking at how freezing was initiated and how it progressed. As HR says, it was tubing that failed. I don't think we have much, if anything to disagree about. We're just checking out different parts of the elephant.

Yours, Larry

I think all the Pex manufacturers have done fail tests with both air pressure and freezing the assemblies.