Is This Normal for Uponor PEX

[Phoenix Is Hot]

Hi everyone. I am wondering if what I noticed about my two year old pex pipes is normal. I noticed yellow discoloration spots at a pipe under a bathroom sink and totally yellow pipes in the 140 degree hot attic where the pipes run. I was told that these clear pipes are better than the red/blue ones but it appears they are breaking down relatively soon. The water pressure is 80 psi and my water company adds chlorine to the water. The hot water temperature is 120 and there is no recirculating pump. Thanks.

 

[Adam F]

Uponor says maximum temperature is 165 so you are close.. I've heard chlorine can impact these pipes. Get a big blue filter with a charcoal filter and that will eliminate the chlorine issue.

 

[breplum]

Not a worry as far as what is known currently.

 

[Phoenix Is Hot]

Thanks for the reply’s. I’m definitely planning on getting a filter for the chlorine. I’m surprised that a material so common could be so quickly be affected by something that’s in almost everyone’s water. Also I wonder if the temperature limit is for the water temperature in the pipes or if it also applies to the air temperature around the pipes?

 

[Adam F]

Thanks for the reply’s. I’m definitely planning on getting a filter for the chlorine. I’m surprised that a material so common could be so quickly be affected by something that’s in almost everyone’s water. Also I wonder if the temperature limit is for the water temperature in the pipes or if it also applies to the air temperature around the pipes?

It isn't a proven fact only an assumption by seeing failures and what they have in common. I don't think where the temperature is matters. It'll heat the water to the same temperature if it isn't being constantly used. Do you have to worry about freezing? Either way I'd look at putting the line under the insulation.

 

[Integrity Repipe]

Your PEX discoloration could be due to a combination of heat, pressure, and chlorine exposure over time. While Uponor PEX is highly durable, clear PEX lacks the extra UV and heat stabilizers found in colored versions, making it more prone to visible aging in hot attic spaces. Since your hot water is set at 120°F, that’s within a safe range, but attic temperatures at 140°F+ can still stress the material. High water pressure also increases the overall strain on the plumbing system. A PRV and insulation around attic-exposed pipes could help slow the aging process and extend their lifespan. If the yellowing is accompanied by cracks or a brittle feel, it may be time for a professional assessment to prevent leaks or failures.