Sub slab forced air system

Have not seen this before. I have sub slabslab Transite system from the "80s.
The supply plenum extends through the basement slab and feeds a sub slab “ductwork”. (pic1) House was built in 1999.

The individual take-offs are openings in what appears to be schedule 20 PVC.(pic 2) A large family room and two bedrooms where ducted this way.

Are there any concerns with the metal duct going through the floor?

Are they any concerns with this type of duct system?

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Mike I don’t see a lot of concern from your pic’s but can not see much!

When ever galvanized sheet metal comes in contact with concrete it has a shorter than normal life expectancy. We use to in the old days coat the exterior surface of any galvanized metal with a tar to prevent corrosion but I am sure that technology dictates some other means in present day construction.

The pic is from a bad angle but you can see where the duct goes through on the left of the furnace. No rust was noted.

Didn’t see any water in the PVC duct, just debris from the original install and a few bugs.



Just looked at one today. Galv. going through floor still looked in great shape. Built in 1955. Ran sewer camera through floor duct, looked dry & in good shape.

That is a new one on me. The second picture is of ???

It’s a little hard to make out in the low res. photo but the white stuff is shavings from when the PVC was drilled to make the hole. Ther are also Asian beetles and a winged insect of some type. It’s much clearer in my original photo.