PEX possible damage from over pressure

[tamuguide]

I moved into my first home this past May. During the home inspection it was discovered the pressure at the hose bibb was in the 100-110 psi range. A pressure reducing valve was installed prior to moving in, I checked the pressure this morning and it was reading closer to 60 psi. Now, within the last month 2 leaks have happened on the PEX water lines in the attic. Both have been on the Hot water lines. The most recent was 3/4" <100' from the hot water heater. The first was 1/2" less than 1' from a copper distribution manifold. I am curious if the high pressure could have caused damage to the lines, what I can do to determine if any other areas are compromised, and what I do to prevent these leaks from happening in the future? Thank you in advance for your response.

Edited to read Pressure Reducing Valve by Admin
10/12/2017

 

[hj]

I hope you mean a pressure reducing valve rather than a pressure relief valve. A relief valve would only KEEP it at the valve's setting, not reduce the pressure. Well, it might reduce the pressure if the excess pressure was dumped on the ground or down a drain and the valve was big enough to drain the water fast enough. There is no way you can tell if there is any damage, or even if the excess pressure caused it, which is not likely. And, thus, no way to prevent future problems. Where were the leaks, in the tubing, fittings, or connections, and what kind of connections and fittings were used?

 

[Sponsor]

 

[tamuguide]

I hope you mean a pressure reducing valve rather than a pressure relief valve. A relief valve would only KEEP it at the valve's setting, not reduce the pressure. Well, it might reduce the pressure if the excess pressure was dumped on the ground or down a drain and the valve was big enough to drain the water fast enough. There is no way you can tell if there is any damage, or even if the excess pressure caused it, which is not likely. And, thus, no way to prevent future problems. Where were the leaks, in the tubing, fittings, or connections, and what kind of connections and fittings were used?

My apologies is was a reducing valve. The connections were crimp on of some kind. The leaks have been on the tubing.

 

[Jadnashua]

Most potable water pex can handle more pressure than you had, some, a lot more. I doubt that caused it to leak, but there are potential exceptions...

the tubing will expand when under pressure some...if it was going through a hole, and it was rough, that could have damaged the tubing. Also, most everything, but plastic tends to do it more, expands and contracts with temperature changes. If there is a clamp or rough surface, over time, the movement during expansion/contraction could rub into it and damage it. It would have to be quite a bit higher to loosen a crimp, but if they weren't done to spec, all bets could be off.

 

[Plumber69]

I thought pex over 100 psi at 120-140 exceeded pex. It was his hot lines

 

[Jadnashua]

Yes, the pressure max depends on the temperature. Here are some generic specifications on pex maximum pressure. You'd want to look up your specific one.

200°F at 80 psi
180°F at 100 psi
74°F at 160 psi

Most can handle 1.5x that for short durations without damage. You can interpolate between those values to get an approximation for your actual temperature water.