pex plumbing problem burst tubing


  #1  
Old 05-31-10, 08:39 PM
S
Member
Thread Starter
Join Date: May 2010
Location: USA
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Angry pex plumbing problem burst tubing

While brushing my teeth, I heard this loud pop from under the bathroom sink. (No water was running at the time) Water immediately came gushing. I ran down and shut off the water main. After cleaning up the spillage, I discovered that the problem was a gapping hole that had erupted in the water line one inch from the 90 degree junction. The product label on the side of the tube reads "PEXc WA G0604638877". It was installed in early '07 by a professional plumbing firm. What might explain the cause of this eruption? Faulty product? Improper installation? What might explain this mysterious event? I want to be armed with as much information as possible before I contact the plumbing firm. I have more of that type of plumbing. Will it happen again? Ideas???????
 
  #2  
Old 06-02-10, 02:17 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,024
Received 1,709 Upvotes on 1,526 Posts
So it was the plastic tubing that failed? Were there any marks to indicate it had been burned or cut?

I have only had PEX fail twice and never what I would call a true failure. Once was my fault when I forgot to crimp a ring so I suppose I cannot blame it on PEX. The other was a line running near some sharp truss brackets. The tubing was rubbing on the sharp metal every time someone turned on/off a faucet upstairs. Eventually the slight movement against sharp metal wore through the plastic and it started leaking.
 
  #3  
Old 06-03-10, 02:13 PM
S
Member
Thread Starter
Join Date: May 2010
Location: USA
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Preliminary results to PEX plumbing failure mystery

It appears as though the "exploding" pipe resulted when it MELTED!
Back in '07, I had the plumber install a Menards purchased Ae 9.5 PowerStar Bosch electric tankless water heater. The local plumber's hook up method was to tap the cold line using PEXc connecting into and out of the tankless water heater. From their they joined the pipe to the hot water line (running from the basement water heater) then these two flowed to the sink faucet. All of this plumbing was 1/2".
Our guess is that the (apparently) extremely hot water coming from the tankless water heater did not move through the pipe as it was unable to compete against the pressure of the water already being fed from the conventional water heater.
We have since learned that when plumbing in a tankless water heater, PEXc manufacturer Viega recommends at least 3 feet of copper before using thier product. Bosch subltly recommends (in a small bullet buried among 5 other "fitting the pipes" section) that "you use 1/2" copper or high pressure flex connections".
The plumber reasoned that because he had used PEXc on boilers and because it is rated at 180 degrees...that it could handle this application as well.
We think that what contributed to the pipe failure was the issue of the heated water's inability to move through the pipe because of the way it was plumbed into the existing hot water line.
The Bosch installation handbook has very limited and poorly written and illustrated plumbing hook up instructions.
The Viega District Sales Manager has sent the piece of piping in for laboratory analysis.
My bathroom renovation goal was to have hot water at the sink without having to waste the tempid water in the pipe while pulling the hot water up from the basement. In hind sight this 240V 40amp "solution" was an extreme overkill. The tankless water heater is now sitting idle and I will be continuing to waste the tempid water as it runs out of the pipe before the useable hot water reaches the tap. I hope others learn from the collective mistakes made in this circumstance.
 
  #4  
Old 06-04-10, 06:20 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,024
Received 1,709 Upvotes on 1,526 Posts
Interesting. I've never installed a tankless water heater but I recall that the steam generator for my steam shower was very specific to use copper only (no plastic of any type) to carry the steam to the shower. After each steam session the steam generator dumps it's water to prevent mineral buildup. I plumbed that line with PEX and it is amazing how much that 6ft length of PEX grows in length when it gets hit with boiling hot water. It's a good thing it's a gravity drain line and not under any pressure.
 
  #5  
Old 06-04-10, 11:00 AM
V
Vey
Vey is offline
Member
Join Date: Mar 2006
Location: Mid-Florida
Posts: 1,343
Upvotes: 0
Received 0 Upvotes on 0 Posts
"I've never installed a tankless water heater"

I replaced one and I can assure you that the water is extremely hot. I used copper up to the sink's special tap because that was what was there from the old one. Didn't give it much thought at the time, but that was the only copper piping in the whole condo.
 
  #6  
Old 06-04-10, 08:25 PM
E
Banned. Rule And/Or Policy Violation
Join Date: May 2007
Location: Wisconsin
Posts: 8,432
Upvotes: 0
Received 1 Upvote on 1 Post
Originally Posted by spark plug View Post
From their they joined the pipe to the hot water line (running from the basement water heater) then these two flowed to the sink faucet. All of this plumbing was 1/2".
Because you say these TWO go to the faucet......you did the w/h and the tankless in parallel (as opposed to in series) so that both the conventional w/h's hot water and tankless hw would both go to the faucet when turned on? Is such a method (even if done 'in series)' something that is recommended?...or NOT recommended? I have never heard of such a method where you retain the the conventional w/h for the same fixture. But I do not really know anything about this. I am just rather curious.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: