Is there such a thing as Plastic Duct work?

[newstudent]

In talking to a contractor they gave me three quotes, one for flex tube, next most expensive was fiberglass duct board, and most expensive was sheet metal.

I thought for sure there would be some cheap chemical weld plastic that everyone was using now a days.

Obviously plastic melts in the heat, but there are a lot of plastics that can take the heat. Is there any reason there isn't a plastic duct work system available?

[54regcab]

Problem with plastic is it needs to be insulated just like metal duct. It costs more than metal duct and isn't a stock item at many supply houses.

[vangoghsear]

There is a CFC free Phenolic foam duct board called "KoolDuct." It is is lighter than metal duct, is foil faced, has insulated/lined acoustic and R-value characteristics, leaks less than metal ductwork sealed to SMACNA Class 6. Better R value than similar thickness of fiberglass ductboard.

Problem is it can only be installed by a certified installer, and it costs more for the materials than metal, but the installation is supposed to be cheaper.

[boilerman856]

I think the big problem with plastics are the smoke and fire ratings.

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[vangoghsear]

Phenolic foam has excellent fire resistance and flame spread ratings and low levels of toxic fume emissions in a fire. It's used as insulation in walls, roof cavities, as sarking boards, and under floors.

[lentz]

Plastic is avilable but every supply does not have it. All the material will have to be ordered. It does make a good job and is easy to insulate.

[genduct]

You have your quotes, so the decision is clear, the FG Trunk with branches ( flex if accessiable andr "hard pipe" insulated if not accessible) and by the way the KoolDuct is very specialized and more expensive than res sheet metal!
I would keep the return short and sweet with transfer (jump) ducts for room returns
Good luck

[vangoghsear]

...and by the way the KoolDuct is very specialized and more expensive than res sheet metal!

I agree. I also said this in my post. I was just answering his question, "Is there such a thing as plastic ductwork?"