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Discussion Starter · #1 ·
I am fixing to plumb a new construction in South East Texas. Single story with a 50% floored attic that will be used about once a week. The home is going to be completely sealed (walls and underside of roof deck) with spray foam insulation. The attic will be lighted with fluorescent lights.

I am a total Newbie. I have been researching like crazy - reading every site including this one. I could never explain how much everyone's previous posts have already helped me. However, now it is my turn, as a newbie, to ask 5 questions.

1) Why does Uponor/Wirsbro have this warning: Do not install Wirsbo PEX between the tub/shoulder valve and tub spout?

Uponor also warns of the following:

Do not spray on or allow organic chemicals, pesticides, strong acids or
strong bases to come into contact with Wirsbo PEX.

Do not use petroleum or solvent-based paints on Wirsbo PEX.

2) Based on the above statements, is it safe to run pex in a wall that will be sprayed with foam insulation?

3) At this point, I plan to run pex as a home run using two Wirsbo Aquacenter manifolds. Since I plan to run the pex through the attic, is it safe to do so (UV wise) since I will have fluorescent lights in the attic that will be used about once a week for several hours at a time?

4) Wirsbo's Aquacenter manifold valves are replaceable. Why would they need to be replaced and how long can I expect them to last? I realize they have O-Rings but is that something that will not last? Furthermore, would it be better to periodically close and reopen these valves or leave them alone until/unless needed?

5) Wirsbo Manifolds contain blue or red clips that not only identify hot or cold outlets but seem to also function as clips that hold that particular valve onto the valve body. Without physically seeing a Wisbo manifold in person, the use of small clips, such as pictured/described in their literature, seem to be an accident waiting to happen. Their own literature says, Caution: Failure to install the valve clip could result in the valve
being blown off when the system is pressurized. For someone who has actually seen one of these manifolds, what do you think is the possibility of a valve being blown off and how hard is it to make sure that the valve clip is properly installed?

Civil Engineer
5,832 Posts
1. Typically an automatic temperature control valve requires copper tubing from the valve to the spout to function correctly because of the physical diameter of the tubing (PEX is a little smaller than copper).

2. You need to check with Wirsbo, or whoever supplies the tubing, to see if their warranty covers use of the specific insulation product you are considering.

3. All PEX tubing is susceptible to embrittlement from UV light, typically from sunlight. You need to check with the fluorescent light manufacturer to determine if the specific fluorescent light you are considering emits UV light.

4. All valves fail eventually, any valve which cannot be replaced is pure trouble. Check the Uponor warranty for expected lifespan of their valves.

5. I did not use the manifold system in my house, I did use Wirsbo tubing with few issues. I would recommend not using brass fitting, the plastic fittings are more reliable in acid water conditions. See the Zurn lawsuit regarding defective brass PEX fittings.
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