This topic contains 6 replies, has 5 voices, and was last updated by 
Miamicuse 7 months ago.
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I have a technical plumbing question on PVC pipes.
A property that I am renovating with the kitchen wall opened up and after redoing the DWV I noticed one day while in the dark attic something that glows like a light saber held in a Jedi’s hands. What the…?
I then realized it is the newly replaced kitchen vent pipe.
Here are some pictures with the light off. If I turn the light on you won’t notice it.
So, I am in South Florida. The SUN is HOT here.
Here are some additional information:
(1) The pipe is standard SCH 40 PVC.
(2) The higher spot at the vent is the brightest, then the intensity reduces as it goes lower.
(3) The illumination starts around 10:30AM, and last till about 2PM each day. It is really brightly lit at noon.
(4) If a cloud passes over or when it rains, no illumination.
(5) The vent pipe protrudes the roof by about 10 inches, and is completely shielded on the outside by old lead flashing, wrapped at the top.
So all this illumination is from the hot Florida sun…ONTO the inside of the PVC pipe.
Everyone says PVC pipe doesn’t do well in direct sun, some paint the outside of the PVC pipe to protect it.
Is this illumination means the INSIDE of vertical PVC pipes are being subjected to UV? Is this a bad thing?
I don’t have an answer but, rather a comment – wow just wow, great pictures and description of a very cool phenomenon.
Will
That is amazing,, It must have something to do with the sun. Here the vent pipes are always the Black ABS stuff. Maybe go on the roof and put a 5gl bucket on the pipe and see if that makes it go dark.
Dirty
A Working Pro since 1988!
Member since January 26, 2013.
My guess is that Luke Skywalker dropped his light saber down the pipe.
Can’t say I have ever seen that before. Sounds like Dirty has a good test for you to try. I guess if it isn’t leaking it should be ok. Maybe you could put some sort of vented cap on top to shade it?
That is amazing,, It must have something to do with the sun. Here the vent pipes are always the Black ABS stuff. Maybe go on the roof and put a 5gl bucket on the pipe and see if that makes it go dark.
I already did something similar. I went up and put my hand over the top of the pipe and someone downstairs told me it went dark.
Can’t say I have ever seen that before. Sounds like Dirty has a good test for you to try. I guess if it isn’t leaking it should be ok. Maybe you could put some sort of vented cap on top to shade it?
Well, it’s an easy problem to solve if it’s a problem. But I am guessing every PVC vent pipe in South Florida has been subjected to this for decades.
I don’t know that it’s a problem. I just never expected that.
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