Uponor PEX- is this normal?

[Embrace the Technology]

Hi everyone. I’m wondering if this is normal for Uponor clear PEX. This is two year old pipe in a two year old house. There’s obvious yellow spots on this cold water line that’s under a sink and doesn’t get any U.V. The lines in the attic are also yellow instead of white after only two years. The water heater is set to 120 and has no recirculating system. It’s in Phoenix AZ so the attic where all the pipes run gets above 140 degrees in the summer. The water pressure is 80psi. Wondering if I should be concerned or if any professional plumbers repair leaks on this often.

 

[HighqualityPlumbing]

I have the same question. On top of what you are describing, my uninstalled pipe that was stored in a dark corner of the garage with window blinds (indirect light of perhaps 5% of normally lit room) got yellow spots and overall yellowed after only a few months.

 

[Sponsor]

 

[Slomoola]

Old thread still relevant.

I had Uponor PEX A with yellowing. It was worse off the hot water tank. Was installed at the start of 2021 till recent time in this house. Posting to show a pattern of pipe performance.

 

[John Gayewski]

It's normal.

 

[piwopok]

View attachment 100303
Hi everyone. I’m wondering if this is normal for Uponor clear PEX. This is two year old pipe in a two year old house. There’s obvious yellow spots on this cold water line that’s under a sink and doesn’t get any U.V. The lines in the attic are also yellow instead of white after only two years to Union Park film. The water heater is set to 120 and has no recirculating system. It’s in Phoenix AZ so the attic where all the pipes run gets above 140 degrees in the summer. The water pressure is 80psi. Wondering if I should be concerned or if any professional plumbers repair leaks on this often.

Yellowing on Uponor clear PEX is normal and mostly cosmetic. Heat and oxidation, especially in a hot attic, will cause it to discolor even on cold water lines. It isn’t a sign of failure on its own. The bigger concern is your water pressure at 80 psi, that’s on the high side, and adding a pressure-reducing valve to bring it closer to 60–65 psi will help protect the piping and fixtures. Unless you see cracks, brittleness, or leaks, there’s no need for repair just because of the color change.

 

[Slomoola]

Puzzled on the fact that the Uponor yellowing is unknown as to the cause.

Fair question here. Do other brands yellow like Uponor?

 

[John Gayewski]

Puzzled on the fact that the Uponor yellowing is unknown as to the cause.

Fair question here. Do other brands yellow like Uponor?

Yes they do it have soiux chief brand in my house and it has yellowed.

It's not unknown. Air diffuser through the pipe. Yellow gets left behind. Also water heaters leave yellow. Water has yellow in it. There are several causes.

 

[Slomoola]

Just did a google search on pex pipe yellowing.

"PEX-A pipe yellowing is a serious indicator of potential failure, often caused by chemical reactions with the water supply, particularly high levels of chlorine and ammonia, which degrade the pipe's polymer structure. Exposure to high heat or sunlight can accelerate this process, leading to internal cracking and "popcorning" or pockmarks on the pipe's surface. While some instances may be cosmetic, yellowing, especially in Uponor PEX-A, has been linked to a class action lawsuit due to increased risk of leaks and pipe failure from the inside out."

Also found a ton of speculation on yellowing. Oh it's normal. Until it leaks.

 

[John Gayewski]

Just did a google search on pex pipe yellowing.

"PEX-A pipe yellowing is a serious indicator of potential failure, often caused by chemical reactions with the water supply, particularly high levels of chlorine and ammonia, which degrade the pipe's polymer structure. Exposure to high heat or sunlight can accelerate this process, leading to internal cracking and "popcorning" or pockmarks on the pipe's surface. While some instances may be cosmetic, yellowing, especially in Uponor PEX-A, has been linked to a class action lawsuit due to increased risk of leaks and pipe failure from the inside out."

Also found a ton of speculation on yellowing. Oh it's normal. Until it leaks.

I'm not sure what you think a google search means. But yellow pex a is more common than pex that hasn't yellowed.

 

[JohnCT]

Just did a google search on pex pipe yellowing.

"PEX-A pipe yellowing is a serious indicator of potential failure, often caused by chemical reactions with the water supply, particularly high levels of chlorine and ammonia, which degrade the pipe's polymer structure.

A lot of the Google AI search returns these days include information scoured from the web that also includes conversations in forums etc. that leads to opinion carrying as much weight as fact.

Regarding the yellow, I have seen Uponor A still in the factory poly bag that has the tell-tale mottled yellow appearance - so no chlorine, no ammonia, no hot water exposure. It could mean the stored pipe was exposed to UV maybe, but there's a lot of speculation and no facts made public. What bothers though me is why the pipe is *splotchy*. If it just yellowed, it would indicate a uniform change in the color of the pipe, but splotchiness means the pipe isn't yellowing uniformly. Instead, some areas yellow and some areas remain white. I would prefer the polymer to be same from molecule to molecule. I would love to see a lab analysis of yellowed areas compared to the white areas.

Because I don't have that info, I won't use or recommend that product anymore because I don't know why it yellows, why it fails, or if the two are even related. I just know if I have the choice to avoid a potential failure by using something else, that's what I'll do.

John

 

[Slomoola]

So are the other brands yellowing too like Uponor?

Is this yellowing PEX wide or just with Uponor?

 

[John Gayewski]

So are the other brands yellowing too like Uponor?

Is this yellowing PEX wide or just with Uponor?

See Above Yes Other Brands Yellow