PEX-AL-PEX Tubing Failure

[Shelterman]

Hi All,

Following a lot of research and information gained mostly from this forum I installed my BioMass 60 with a 1000 gal storage tank which has been working very well for me for the last 3 winters now. The furnace and storage tank are located in an outbuilding about 100' from my 4000 sq ft home. Between the buildings I buried four 1" PEX-AL-PEX pipes (I have 2 separate zones in my home) which were well insulated by constructing a box out of rigid polyurethane insulation board (the kind designed for underground applications) and then poured 2-part pourable urethane foam around the evenly separated pipes. All of this was completely surrounded by 3-4" of 1/2" gravel to eliminate the possibility of a sharp rock puncturing a line and also to facilitate drainage of groundwater.

Aside from a few minor leaks, this setup has worked flawlessly for me for the last 3 winters...till this Fall. One evening last week I noticed I was losing heat rapidly from one of my zones. I was able to determine which pipe was leaking and shut it down, continuing to heat my home with the remaining zone. Since I knew which pipe had failed and hence the location of the pipe in the insulated box, I started digging on the appropriate side of the lines with my tractor and front-end loader till I found the failure.

As you can see from the attached photos, the failure is a lateral split approx. 10" long along the side of the tube. My question to anyone that can answer is how could this have possibly happened? I went the PEX-AL-PEX route because of the extremely low failure rate of this stuff (I purchased the tubing from Cozy Heat). The highest water temperature to ever go through this is 185 deg F, pressure never over 20 psi.

My next question is how do I best make the repair on this? I suppose a couple of compression couplings http://cozyheat.3dcartstores.com/Compression-Coupling_p_427.html with a piece of scrap tubing between them would maybe work, but surely someone makes a repair coupling designed for an onsite repair.

Any help would be appreciated.

David

http://s826.photobucket.com/user/Shelterman33/media/2013-10-27_19-11-15_614.jpg.html
http://s826.photobucket.com/user/Shelterman33/media/2013-10-27_17-52-57_857.jpg.html
http://s826.photobucket.com/user/Shelterman33/media/2013-10-27_18-05-12_669.jpg.html
http://s826.photobucket.com/user/Shelterman33/media/2013-10-27_18-15-08_945.jpg.html

 

[heaterman]

I don't see your pictures but is the tubing Kitec brand?

 

[Shelterman]

Refresh the thread Heaterman. I just now noticed that the "image" function didn't work so I posted the links to the images as text.

The printing on the tubing says WSD as the brand...."Made in China". The Made in China part may be my problem ;(

 

[Frozen Canuck]

I can't really tell from the photos Steve. In some the pipe looks orange, in others red.

Edit just read the update about made in china. Sorry but that's really bad news, virtually no QC there.

 

[heaterman]

From what you are describing about your operating temps I can't see any reason for the failure other than the tube itself. That really sucks.

I have to say though that I offer both bargain basement tube (Rifeng) and top notch stuff (Viega) There is virtually no warranty on the Chinese tube and Viega backs theirs with both materials AND labor.

Guess which tube 9 out of 10 people buy.........

 

[Shelterman]

Well, hopefully it was just an isolated flaw in the aluminum or something.

Any thoughts on how to repair? Do they make a repair coupling? I've searched but can only find a standard compression coupling.

 

[Frozen Canuck]

I don't like being the bearer of bad news however unless there was a reason for the pipe to fail (abuse, driven on, etc) it will likely reoccur in other areas. Most likely a manufacturing defect.

Like Steve said above (kinda) good pipe is priceless. Imagine if you did this for a living, say 10 installs/month & then 3 years later the calls start coming & won't stop, not having those calls.....well that's the true value of quality pipe.

You can patch it (likely) with a crimp on coupling or a compression fitting. Most/all pipe manufacturers have there own specific pipe ID's & OD's & therefore you can only use their fittings (in most cases). Shark Bite fittings will work on a variety of pipe but are pricey.

Try not to plant anything you don't want to part with in the area of the pipe, you may be doing this again.

 

[JTWALL]

Sorry to see this failure...bitter pill for sure and with winter approaching no less.

Just a suggestion, if you replace the tubing, place them inside a larger tube (i.e., sewer pipe). Insulate the outside of the larger tube only. That way, if a future problem occurs, you simply pull out old and install new. Saves time, digging, and a lot of aggrivation. Good luck!

 

[DaveBP]

If you can peel the outer sleeve of plastic off the aluminum you might be able to see if the split is along the weld in the aluminum. If it is, it could be just an isolated quality issue. Never to repeated.
Wishful thinking is sometimes the only easy option.

 

[Shelterman]

I want to thank everyone for their responses. They were all very helpful. I've ordered a couple of repair couplings and have made a temporary repair to the line so I can start heating with that zone again. We are expecting a rainy week here in southern Missouri so I put a sump pump at the lowest point of the trench so I can pump out the unwanted pond that will surely form in my backyard. When my couplings arrive and things dry out I will put everything back together and pray I don't have a repeat occurrence.

 

[woodsmaster]

there's why I bought thermopex. I couldn't imagine it ever splitting as thick as it is and encased in foam.

 

[arbutus]

Guess which tube 9 out of 10 people buy.........

I would guess Chinese.


Good luck Shelterman

 

[peakbagger]

I would consider pressure testing the remaining line. Pick the rated pressure and pressurize the line to that pressure and leave it overnight. Hopefully you are running much lower than rated pressure. Odds are good if it defective it will split