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Discussion Starter · #1 ·
I want to reroute one 8' section of 3/8" PEX line, that is completely indoors, for my solar water heater. The roof water temp sensor has registered at least 175 degrees (outside air temp 110 :furious: ). What is the difference between red, white, blue, orange, and black PEX line?
 

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I don't think there is a uniform color coding format for PEX. I know that my Wirsbo Aquapex (potable water only) comes in several different colors, each with apparently identical properties. There is also hot water heating PEX, which includes a variety of additives to make the PEX resistant to damage.

A couple of things to bear in mind. PEX is not rated for outdoor use due to UV, but I suspect you know this. Plumbing PEX (Wirsbo Aquapex) is rated to 180 degrees F. Heating PEX is apparently rated to 200 degrees F, but I have not worked with that material. Check with the manufacturer of your specific PEX type for allowable temperature rating.
 

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Discussion Starter · #3 ·
I was told that the black PEX, that was used inside and on my roof for the solar heater, is UV resistant. Here in AZ it will not take very long to verify that fact.

The plumber who did the installation had some disdain for construction crews that drive around in open pickup trucks with non-black PEX in the bed. I noticed that on their online websites, Lowes and Home Depot do not carry black PEX.

If I cannot find UV resistant PEX, I will look for the highest temp rating; 180 should be adequate. I would prefer to get UV resistant as I could make any necessary roof repairs.

Thanks
 

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Just call me Andrew
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Heating pex is not just different in terms of max temp, it also has an oxygen barrier that leads to less corosion of parts in boilers. Not sure if this is applicable to your situation.

[quote="Pexinfo.com]
Oxygen Barriers

Some applications require PEX with added oxygen barrier properties. Radiant floor heating (or hydronic heating systems) may include some ferrous (iron-containing) components which will corrode over time if exposed to oxygen. Since standard PEX tubing allows some oxygen to penetrate through the tube walls, various "Oxygen Barrier PEX" tubing has been designed to prevent diffusion of oxygen into these systems. Two types of specialty PEX pipe are offered:[/quote]
 

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Discussion Starter · #5 ·
More good info; thanks. The pex line in my app has 'Fafco UV Restitant Solar Tubing' stamped on it. I should be able to get it directly from Fafco, but I am sure it will be pricey.
 

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According to NIBCO:

UV-Resistant - PEX tubing contains UV stabilizers to protect against short-term exposure to damaging sunlight.

Note the short term part. I am not sure there is a long term sunlight resistant PEX made. As for the temperature rating, potable water is 180 degrees F, radiant heat is 200 degrees F. If I were using it for a solar application, I believe I would go with the 200 degrees, but I would not use PEX in any application where it was exposed to sunlight, unless you can find a supplier that warranties their specific PEX for sunlight conditions.
 

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I want to reroute one 8' section of 3/8" PEX line, that is completely indoors, for my solar water heater.
Regarding running a PEX line where it will be exposed to sunlight, an alternative might be to run it inside a length of PVC pipe. Where the PEX exits the PVC pipe, build a box to shield that portion.

HRG
 

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Discussion Starter · #8 ·
I am assuming that the pex used in my application is UV resistant as it is part of the solar heater package. It has also been inspected (for my rebate) by the Salt River Project, which is my power company, and they had no problem with it.

However, I do think that sheathing the pex in PVC is a good idea. AZ deserts are much closer to the Sun than the rest of the planet.
 

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Oscar,

On all of the solar system installs I have been involved with we usually run 1/2 copper from right underneath the solar array straight into the attic. Why do you want to run 8' exposed on the roof? I've never heard to 'black' pex, but I'll bet that you local plumbing supply house should carry it.

I've seen ABS and PVC mounted on roofs for pool solar heating and they usually do not last all that long, ~ 4-5 years.

If you really have to mount this on the roof and cannot source this black pex then why not try some kind of metal shroud? Similar to this

but a thicker gauge and with the flaps bent outwards. Insulate the hell out of the lines, tar the edges of the metal and then screw them down. There's probably a better way to to seal and maybe someone else can chime in.

Please note that I've never tried this, but I believe that it'll last longer than the other methods I mentioned and I've seen those in person.
 

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However, I do think that sheathing the pex in PVC is a good idea. AZ deserts are much closer to the Sun than the rest of the planet.
If you use PVC, be sure to paint it to protect it from UV from the sun. I read about doing that when researching drip irrigation systems.

HRG
 
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