Uponor PEX UV degradation?

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Aberrant

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I have some weird yellowing that seems to be occurring only on my hot water lines. It’s yellow spots and it’s almost like a powdery substance on the outside of the pipe. The pipe is in the basement near a window but does not get direct sunlight. There’s a cold water line near it that doesn’t have any yellow spots on it. The PEX was installed about 1 year ago.

I can wipe most of the yellow away but there is some residual that looks like it’s stained the pipe. Has anyone experienced this? Is it algae? Could it be from indirect UV exposure? Do I need to be concerned? I’m planning to cover the pipe with insulation but worried about any permanent damage or degradation.

I’m planning to install a whole house charcoal filter to completely remove any chlorine. Would this prevent any degradation caused from UV damage to the pipe from degrading further? Should I replace this?

It kind of looks like this picture from a site about PEX chlorine/UV damage: https://images.app.goo.gl/D34cZzGudSHWkKuC7
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Aberrant

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This is another section on the hot side further down the line tucked up in a ceiling joist. Again, I am only seeing this discoloration on the hot line, other sections of PEX in this area on the cold side are perfectly fine. Is this something with the hot water causing this?
IMG_5324.jpg
 

Aberrant

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I just started insulating recently, it had been uncovered since it was installed about a year ago.
 

Breplum

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Yellowing is normal and common with Uponor PEX, esp on the hot side. Check out this formerly white ring on a failed red Uponor PEX line
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royalflush001

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There could be several possibilities including:
1. Algae or fungi can grow in moist environments, especially in the presence of sunlight. If your hot water lines are exposed to indirect sunlight, it's possible that some type of growth is occurring, leading to yellow spots and powdery substances.
2. Certain chemicals or minerals in the water could be reacting with the PEX material, causing discoloration and powdery residue.
3. Even if the hot water lines are not in direct sunlight, some types of plastics and PEX pipes can be affected by UV exposure over time, leading to degradation and discoloration.

If you find that UV exposure is causing the issue, you might consider using pipe materials that are more resistant to UV damage in the future. If you are unsure about the cause or severity of the issue, it's best to consult a professional plumber or water quality expert.
 

JohnCT

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Unfortunately, all we can do is speculate right now. If anyone knows for *sure*, they're not saying.

If this is new plumbing that is confined to the basement, I wouldn't worry about it unless it's a finished basement. If it's just a basement, keep your eye on it every year or so and look carefully for any sign of cracking near the expansions which would indicate impending pipe failure. On the other hand, if it's confined to some recent rework in the basement and is easy to access, you can always replace it.

By now, everyone has read about a small percentage of Uponor pipe failures, and *some* people (youtube "experts") seem to think the pipe is being chemically burned by excessive chlorine or chloramine. I am not aware of any cases where the pipe failures have occurred on houses with wells which would eliminate chlorine if some failures occurred on wells.

The common denominator that I've seen is that all the failed pipe I've seen has been yellowed. This doesn't mean yellowing is necessarily bad, but I haven't seen any pics of failed Uponor that wasn't yellowed.

My buddy has white Uponor in his finished basement that I installed 10 years ago and it's spotless (I checked recently) with zero signs of yellowing. It literally looks like we installed yesterday. We live in a small town and we have wells, although he might be connecting to a water main from our neighboring city as the part of our town was overdeveloped in the 1960s.

Most failures that have been made public seem to strongly point to the hot water side failing first. I suppose that if a problem occurs and a repipe happens, the cold water pipe gets changed at the same time and eliminates the cold side failing some years later that might have happened if it wasn't replaced. Some people say NOT to use Uponor A on any hot water recirc system under any conditions. Honestly, I don't know if I'd be comfortable using anything other than copper on a recirc line.

All PEX is susceptible to UV, and even in a basement, there is often some scattered outdoor light that gets inside. The UV damage is cumulative, so even a little reflected light has some effect over the months and years.

You said you think the yellowing is on the outside. I would carefully clean it with a scrunge and soap and water (no chemical cleaners) and see. If it's just on the outside, then it could be some mold or algae growing on it although I would think this would happen on the cold line first.

John
 

Jeff H Young

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A few points he said that are easy to miss.
1 Pex was installed around a year ago
2 yellowing on the outside and it wipes away.
it seems when water leaks down on a light color surface yellow or brownish stains occur a possibility?
 

Aberrant

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I am able to wipe off a majority of the yellow but there's some residual spots that seem to have permanently stained the pipe. I am in the middle of finishing the basement which is why I'm so concerned.
 

JohnCT

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I am in the middle of finishing the basement which is why I'm so concerned.

If all the PEX we're talking about is in the basement and accessible, I for one would replace it, but that's me and certainly not a recommendation for you to do so. The reason *I* would change it all out is that it would be a constant thought - every time I walked into the room I would be looking at the ceiling or wall for water spots.

John
 

Aberrant

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Thanks everyone for your replies. I was finally able to get through to technical service at Upon and they confirmed over the phone that anything on the outside of the pipe is unrelated and likely caused from some external factor unrelated to the performance of the pipe. They confirmed that yellowing of the pipe is common and typically happens first on the hot and will eventually occur on the cold too. It manifests as a yellow/brown color and is perfectly normal.

I asked if it could be the result of UV damage and they said that UV damage will mostly appear as stringing and cracking of the pipe (similar to Breplum's picture above) as opposed to discoloration.

I've wrapped all exposed sections of PEX at this point and I'm already planning to install a whole house charcoal filter to remove all chlorine in the water. I figure even if there is/was UV damage to the PEX there will be no chlorine in the water to cause a failure. I recently learned that UV doesn't damage the pipe it destroys the barrier that prevents chlorine from damaging the pipe, so by removing the chlorine these pipes should outlive me!
 

JohnCT

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I recently learned that UV doesn't damage the pipe it destroys the barrier that prevents chlorine from damaging the pipe, so by removing the chlorine these pipes should outlive me!

Thanks for the update. Time will tell about the yellowing. I still find it strange that yellowed pipe has been found on the same job as non-yellowed pipe - same water, same temp, same age, same conditions, etc.

I can't recall any instances of failed Uponor on well water (unless I missed it) so if chlorine is an issue, then maybe all installs should have a filter for peace of mind, particularly if some municipalities have changed their water chemistry in recent years.

John
 
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