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Type SR Air Duct Material


Brian G
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I just did a 70's house with a duct material I've never seen before. It was labeled:

Johns-Manville

Micro-Aire

Type SR

Air Duct Material

Class 1

It was semi-rigid, like a foam, with a plastic outer jacket. The pieces were taped together on the outside, but had metal underneath at the branches. Is anybody up on this stuff? Does it have a history of problems?

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Brian G.

Another Day in the Endless Variety of Building Materials [:-crazy]

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Brian,

Is it square, or round with a dark gray jacket? The older stuff is round and the plastic jacket will split and leak a lot of air. I was at a house recently where the HVAC estimator said his company always replaces this stuff becuase of possible health concerns. I tried uploading a pic, but it is too large. Ouch.

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Mine is round. I can find all kinds of info on the flat sheets and square stuff, but nothing on the round. I didn't see any splits in the outside, but I wasn't impressed by it either.

Did the guy offer any specifics about the health concerns?

Brian G.

It Makes My Head Hurt; Does That Count? [:-headach

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Originally posted by Brian G.

Mine is round. I can find all kinds of info on the flat sheets and square stuff, but nothing on the round. I didn't see any splits in the outside, but I wasn't impressed by it either.

Did the guy offer any specifics about the health concerns?

Brian G.

It Makes My Head Hurt; Does That Count? [:-headach

It looks like regular old fiberglass duct.

Some people believe that fiberglass will become the new asbestos. They've been saying this for 20 years. I don't happen to share the concern.

- Jim Katen, Oregon

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Originally posted by Brian G.

Originally posted by Jim Katen

Some people believe that fiberglass will become the new asbestos. They've been saying this for 20 years.

Well, we always seem to need a new asbestos, don't we?

Brian G.

Land of the Brave, Home of the Class Action Lawsuit [:-tophat]

Not yet. We've still got mold, West Nile virus and bird flu. Fiberglass will have to get in line and wait, just like all the other deadly hazards.

- Jim Katen, Oregon

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  • 2 weeks later...

Brian G.

I see this material quite often in homes built during the 70's. Based on the research I have done I have done including talking with HVAC contractors and competent inspectors, I refer this for further evaluation stating health concerns. The duct material is comprised almost entirely of a fiberglass wool and over time this material may deteriorate causing the fiberglass particles to become airborne. These particles may cause irritation to persons with sensitive respiratory systems. Upon googling this material, most of what you will find is new product information for Johns-Manville. I did not find an article which describes this material and states the related health concerns. The trade name does not exactly match the stuff I have come across but the physical description and manufacturer is the same. See attached link.

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In the 90's I worked for a HVAC company who installed a large volume of this stuff. We too found that it was not the best for health reasons as more and more people are sensitive to just about everything. We had a machine that cut the flat sheets into every size and shape. We even cut it to be round, as round sometimes was easier to run and support. It us now more commonly used as a metal duct insulation.

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