Thread: PEX in return air

Is the PEX manifold for a condo allowed to be inside the return air chamber? A condo development near me is built with the manifolds within the actual chamber. I thought plastic lines of any sort, plumbing or electrical, were prohibited from the return air system on account of fumes in case of fire. I raised the question on the first one I inspected, only to have the city inspection department laugh at it. They say it is fine. I still don't like it; I think there should be some sort of isolation between the two. Am I in left field?

Similar Threads:

• Return for repairs, Stinger Strion?
• Fresh Air Return
• Return Air
• Exposed wood joist in return air
• return over range in kitchen

The "manifold" is in the return air? In other words, do you have to open the duct work to view it? A photo would be helpful.

Originally Posted by Linda Swearingen

Is the PEX manifold for a condo allowed to be inside the return air chamber? A condo development near me is built with the manifolds within the actual chamber. I thought plastic lines of any sort, plumbing or electrical, were prohibited from the return air system on account of fumes in case of fire. I raised the question on the first one I inspected, only to have the city inspection department laugh at it. They say it is fine. I still don't like it; I think there should be some sort of isolation between the two. Am I in left field?

Hi Linda,

The first thing I think about is how the PEX lines are supported, how the manifold is supported and how they sealed the return to make it air tight?

All PEX manufacturers have very specific install guidelines that list their Do's and Don'ts? The biggest is restricting the movement of the PEX (not allowing it to expand and contract or move as the water flows through the lines) and supporting the PEX lines properly. If PEX is restricted it will pull away from the connections and you will have leaks, this is a proven fact.

I can already see a problem with the PEX in the air return. If the return was sealed properly then the PEX line has been restricted so it can not move as required by ALL of the PEX manufacturers! Then you have to wonder how the PEX lines and the manifold are supported, this is most likely another violation of the install guidelines. Oh, I forgot to add that I think all also require the manifold to be accessible.

I think that if you change the way you are reporting or inquiring about this with the AHJ, and approach it from violations of the manufacturers installation guidelines you might get them to realize the problem.

I hope this helps......

In this part of the country No Nothing in the duct work