Pex pipe rupture on owb

[Poston5]

Last week I noticed that my pex that is the feed to the furnace split and ruptured causing a massive leak so I patched it. This leak happened in the back of my hardy h2 and the pex seemed dry rotted and it actually is crunchy to cut and crimp.

I sprung another leak yesterday and had to patch it again but this time on the return side from the furnace. Unfortunately this second leak is below ground therefore I just unhooked my domestic water return and I am using it as my furnace return. H2 run 4 pipes not 2 pipes, so currently I have 3 that still hold water.

After all of this I noticed that both pex pipes that carry furnace water are in really bad shape but the pipe that carried the domestic feeding the hot water tank is still in good shape.

I run my temp around 170 and keep roughly a 5 degree differential. The pex was installed in the winter of 2013 and didn't have any underground connections. I only burn in the winter months and I am at a loss for words on why this is happening. The entire pex line set is going to need replaced this is for sure just a patch to try to get by.

I also checked the pH of the water and it looks to be about 7.

Does anyone know why this may be happening and what could cause it?

I called the material supply house where it was purchased and they said that they have never heard of it and they want me to send the pipes to them so they can see them. They said it should last for 25 years.

 

[cantoo]

Wow, looks like way too hot a temp to me but I don't think that is possible. Stretched during installation maybe?

 

[lindnova]

Not good. Only 3 years? Never heard of this. Must be a manufacturing defect. What brand?

I am interested to hear what the supply house and manufacturer find out.

 

[Poston5]

Wow, looks like way too hot a temp to me but I don't think that is possible. Stretched during installation maybe?

I installed it myself and know that nothing happened to it. I just used a string to feed it through above grade and then threw it all in the ditch. Even pieces in the basement are in horrible shape once i cut into them. I think it's rated at 200 degrees and 80 psi and on my open system.

 

[hedge hog]

Interested


Sent from my iPhone using Tapatalk

 

[Poston5]

Not good. Only 3 years? Never heard of this. Must be a manufacturing defect. What brand?

I am interested to hear what the supply house and manufacturer find out.

I will let you know when I hear back from them. So far they are at least talking to me rather than telling me good luck. I am mailing it out tomorrow to the supply house.

 

[Poston5]

This picture shows 3 of the 4 pipes. Red upper left is from pump to furnace. Blue upper right is return from furnace to boiler. Red in my hand is domestic return from boiler to hot water tank. Notice how much better shape the domestic is, which is a much cooler but higher pressure conduit.

 

[cantoo]

I know my system has been over 200 a couple of times because it boiled over. I'm going to have to take a look at mine and see what the top temp rating is. Just took a look and all mine says is "rated for 100 psi at 180*" Hmm that doesn't sound good.

 

[dave_dj1]

All pex is not created equal.
They make a special pex for hot water boilers, its pex-al-pex it has an oxygen barrier.
"
PEX-AL-PEX differentiates itself from standard PEX with its Aluminum core. This allows it to expand less at high temperatures and hold its shape better than regular PEX."

http://www.supplyhouse.com/PEX-AL-PEX-21807000
http://www.supplyhouse.com/Rifeng-PEX-AL-PEX-Tubing-12212000

 

[lindnova]

All pex is not created equal.
They make a special pex for hot water boilers, its pex-al-pex it has an oxygen barrier.
"
PEX-AL-PEX differentiates itself from standard PEX with its Aluminum core. This allows it to expand less at high temperatures and hold its shape better than regular PEX."

http://www.supplyhouse.com/PEX-AL-PEX-21807000

I have Kitec Pex-Al-Pex no problems except one leaking fitting in 10 years - yes that is the pipe with the class action lawsuit on the fittings.

Thermopex doesn't have any aluminum and seems to work great. It is able to manage expansion ok.

 

[StihlKicking]

I suspect at some point you sent 200 degree plus water through those pipes. That's what it looks like and that would explain why you DHW pipes are still good.

 

[ChoppyChoppy]

Is that domestic water pex? There is a different pex for boilers.
Is it covered? UV will kill pex.

 

[Poston5]

Is that domestic water pex? There is a different pex for boilers.
Is it covered? UV will kill pex.

Yea it is covered, it is in the ground, in my basement and in my boiler. As for domestic pex vs boiler pex. It was all purchased from an outdoor boiler website that sells this stuff everyday, per my phone call with them yesterday.

 

[Poston5]

I suspect at some point you sent 200 degree plus water through those pipes. That's what it looks like and that would explain why you DHW pipes are still good.

The pex is rated at 200 degrees at 80 psi. So I don't think there is a way that the 200 degree temps are affecting it since it is an open system with no pressure. My typical temps are around 170.

 

[Poston5]

Can the water quality hurt the pex? My situation has the current pH around 7 and the boiler water is running my domestic water in it since I have the auto fill feature on my boiler. Therefore both loops (domestic and furnace) have the same water source just one is fresher than the other.

 

[Frogfarmer]

It's a manufacturer problem. That PEX has been cooked. It wasn't up to standard.

 

[StihlKicking]

The pex is rated at 200 degrees at 80 psi. So I don't think there is a way that the 200 degree temps are affecting it since it is an open system with no pressure. My typical temps are around 170.

I have the exact same heater as you. A hardy H2 with 4 pex pipes. The 200 degree rating is independent of the psi. If you push water that's over 200 degrees through those pipes it will break them down regardless of what the pressure is. Trust me I have seen it happen. The dead give away is that your DHW pex is fine given that the water that passes through them is always cooler than that going to your heat exchanger. Also the pics you posted look just like the pex I've seen cooked by water that was too hot.

 

[NSMaple1]

I don't think it's breakdown from hot water. From what I read, all the boiler piping is showing it, even in the basement. Even if the boiler gets over 200, the return line shouldn't see that hot due to heat loss. Or the basement. Sounds like defective product IMO.

 

[hardy steve]

I had al -pex go bad after 3 years myself. Had it crack and sep thru on 3 different bends .2 cracks on hot water one on cold .So I ruled out heat. Could not find transaction online to save my ass.Bought all new pex never looked back.

 

[ChoppyChoppy]

By any chance was it stored outside before install?

We had a roll that was outside for a yr or two. Went to use and it was junk, couldn't even unroll it without it cracking apart.