Why would NIBCO/CPI Durapex PEX split (lengthwise) and leak?

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celiason

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I hope someone can help me or at least point me in the right direction.

We built our house in 1999 (completed) and the house is plumbed with PEX. In the last six months, the PEX line coming from our water heater has split three times (hot water side). Each time we have had it replaced and each split has been farther down the run each time. The entire affected length appears to be approximately 4 feet. The water heater is in the attic, we are on county (treated) water and live in central NC. We have a PRV and expansion tank. The splits are not near a joint, fitting or bend and are lengthwise (almost like a seam "split" ) at about 1-2 inches in length. I am not sure who the manufacturer is ( there is a logo I am still trying to ID for contact info), but my plumber says it looks like CPI (NIBCO) pex. The manufacture date on the PEX says October 1998 (we started building in September 1998). We have not had any problems anywhere else in the house...

Has anyone ever heard of such a thing? I thought this stuff was supposed to last a lot longer. I know that if PEX is exposed to sunlight it can be affected, but I am pretty sure this was not the case when our home was built...
I have tried to include as much info as I can...
Any help would be greatly appreciated...
THANKS!!!
 
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Master Plumber Mark

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treated water and PEX

Nibco is not one of the better brands out there...

it sounds like a manufacture problem
if it is splitting up the pipe on the hot side only??


or....the only other thing I could think is going on is the
chlorine in the treated city water is affecting the PEX pipe very rapidly....only 10 years old is not a good sign......

but you will be seeing more of this type of trouble
as the years pass by with all brands of PEX....
 

rmelo99

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Can you plumb all the way to the water heater with pex? I thought u had to transition to either copper or some other metallic tubing close to the water heater?
 

Cass

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Have you checked the water temp coming out of the heater?

It could be bad thermostats heating the H2O to to high a temperature.

Have you checked the water pressure?
 

Cass

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I would replace as much of the exposed PEX in the attic as is possible and take a utility knife and cut it in half length wise and inspect the inside of it. You may see signs of what is going on just prior to the bursting.
 

celiason

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Thanks for responses!

Thank you to everyone who responded. I will let my husband know anything else that you tell me...

dwpecksr Thank you and I will keep you updated on what I find out...

rmelo99 and Redwood Yes, there is at least 18" of copper from the heater to the "replaced" pex. (sorry I didn't include that piece of info....:eek:

Cass I have checked the water temp at 120-125 degrees F and the pressure is 55 psi (these are within the ratings printed on the original PEX). After the second PEX split, we had the heater replaced, the PRV replaced and installed an expansion tank (which I think is now code in our locale now for "closed" systems). Since split #3, we have replaced the PEX from the water heater down to the attic floor/hall ceiling. All work has been done by a licensed plumber with a great reputation in our area...the PEX was replaced for us on a "call" basis...it busted, we called them, and they came out and fixed it... Upon inspection of the failed PEX, there is no apparent "wear and tear", the PEX just has a lengthwise split in it like a seam split for about 1-2 inches...I will check with our water department for past chlorine levels, but the two houses on either side of us (same builder) have not had similar problems...

I have someone I trust coming out to look at the PEX that failed (I have saved every section...) and we will discuss options...

I am still trying to ID the logo on the PEX. Maybe someone can help...It kind of looks like a W on top of an M and a registration "R" to the right of it. I don't think it is Weil-McLain because the logo on their site is different...but I guess they could have modified it in the last 9 years...

Thanks again to ALL for your input...I will keep checking back and keep you posted...

I AM SO GLAD I FOUND THIS SITE!!! CELIASON
 
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celiason

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I have identified the PEX!

After scrutinizing the PEX sections I found brand name -DURA PEX. I have left a message for their area representative (NIBCO) to contact me... Wish me luck...
Again, thank you to all who responded...(if you are interested, check back and I will try to keep you updated periodically).
-celiason
 

celiason

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Update (FYI)

I have contacted the technical service dept. at NIBCO and sent one of the sections of split Durapex to them for analysis...we shall see what happens....

Thanks again for everyone's input. I am learning alot about plumbing from this forum.

.........stay tuned.........
 
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I have two questions:
First, what color is the pex? Just curious. There is alot of red and blue pex installed down here in southwest Florida...but the only pex we seem to be having problems with is the white stuff. We've sent samples back to the manufacturer as well and all the results were the same, damaged due to excessive UV exposure.
Second, what is the purpose of putting 18" of copper above the water heater before going to Pex? Pex will withstand 100 psi at 180 degrees. We pipe right to the top of the heater with pex. I've seen guys melt pex while soldering close to a wall (example, while replacing a valve above a water heater). The heat rises up the copper, chimney effect, melts the pex.
 

mc_1_2_3

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UV exposure

Is there a window in the attic, or some other opening, that allows light from outside to hit the pex tubing in the attic? As far as I know, all pex tubing must be protected from UV light.
 

celiason

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Sandpiper-

Thank you for your interest! The pex in question is red in color, brand name Durapex, manufactured by NIBCO/CPI. As for your question about the 18" from the water heater, I do not know. Hopefully one of the other plumbers here can offer reasons for the spacing. Our pex appears to be plumbed to the copper pipe that comes out of the heater and it is long (I haven't measured it but I roughly estimate it to be at least 18"...). As for our situation, the splits have been occuring off the hot water supply side of the water heater, but well away from the water heater-copper itself...they are lengthwise and about 1-2" long... all in the same "run" of pex, just consecutively further down the pipe each time...We have replaced the portion in the attic and now the run is coming down through an interior wall in our hallway.

Has anyone else experienced similar issues with this manufacturer (NIBCO/CPI)?
 
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celiason

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No light in attic...

mc 1 2 3-

Thanks for your interest! In answer to your question, there is not a window or opening in the attic that would allow any UV light exposure to the pipe. I have been up there during the day and it is DARK! The only natural light source I can see is dimly through the soffets and they are at the perimeter of the attic, well away from any of the Durapex. The majority of the pipe is running through the interior walls and the ceiling of our finished (EEK!) full basement. Therefore, there is no UV exposure to any of the product...
 

jadnashua

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On a gas or oil-fired WH, you want to protect the pex from possible exposure to the flue gasses. Plus, if the thermostat were to fail, before the T&P valve relieved pressure, the significant heat might exceed the specifications of the plastic pipe material. With the pressure in the tank, like the radiator of a car, the water temperature could exceed normal boiling point. So, to protect the pipe from that potentially excessive heat or exposure to flue gasses, the connection to the tank must be metal; then you can convert to an approved alternate pipe. That stub of metal also acts as a radiator, and moderates the temperature some before it hits the plastic.
 

celiason

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jadnashua-

Thanks for explaining the copper to pex question. Makes sense to me.
I am enjoying exploring this site and I am learning so much...
I may not be ready to tackle a major job, but at least I feel I can now understand how things work and ask coherent questions when something comes up! :^)
 

Bob NH

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One possibile cause of the split would be if it was damaged when pulling it through holes or over a sharp object during installation. A very small scratch can cause high stresses if the pipe hardens with age.

If you get any more splits I suggest taking out the whole length to the extent that it is accessible. If something is weak it fails at the weakest part. When you remove that weakest part you leave other parts that are nearly as weak. If you want to avoid more breaks you should do that before you get any more breaks, which are probably inevitable.

There is an interesting aspect of strength of certain types of materials. Someone determined that the average breaking strength of a large number of samples of long pieces of string is less than the average breaking strength of the same number of short pieces of string. The reason is that there are more weak spots in the long pieces.
 

Mikey

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That is interesting, and very logical. Assuming the breaking strengths of "weak points" are normally distributed, there's more opportunity for an outlier weak spot to be in a long length. Of course, there will also be outlier strong spots, but they won't fail until all the weaker ones have. With the right equipment and way too much time on your hands, you could determine the distribution of weak spots in a string by succesively testing the remnants after each break. I'm sure the Acme corporation does this.

http://en.wikipedia.org/wiki/Acme_Corporation

The next time I go mountain climbing, I'll be sure to use the shortest rope possible :D.
 

Cass

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It could be that the PEX didn't cross link right in spots in that particular batch or maybe even that roll.
 
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