Insulation in heating/ac ducts?

[msheepers]

Hi all -

Can you tell me - should there be an insulation-looking material lining the INSIDE our heating/ac exhaust ducts? (This particular duct is in the kitchen and shoots right off the unit, which is also in the kitchen.) I thought that you were only supposed to insulate the OUTSIDE of the ducts and that there wasn't supposed to be anything in the inside...

(Background: The condo was built in the 1960s, and my fiance moved in about a year ago. We just discovered the inside condition of this duct yesterday.)

Anyway, it's pretty nasty inside there. The material is all black and some of it is wet. (Although it's possible that the wetness could be due to higher-than-normal humidity in the house b/c we've had the outside doors open as we've been working on the kitchen... I don't know for sure.) Anyway, the material is held along the edges of the duct by metal pieces that are folded over it like tape. The duct itself also appears to be sagging at the top.

My thought is that this material should not be inside of the duct and that its presence is making the air unhealty...

Or is this material supposed to be in there, but it needs to be replaced?

Thanks.

[DanG]

Fiberglass lined metal duct work is still the normal install for rectangular metal duct. The material is black the day it is installed. The duct work needs to be insulated, especially if you have air conditioning. The lined duct is difficult to clean.

We have excluded inside insulation for the last 5 years and demand that the duct be insulated on the outside. The inside material can be prone to mold growth and is easily distributed throughout the living space. In the law suit happy society in which we live and the "sick building" articles addressing matters of IAC we felt it was prudent to make the shift.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG

in the

anything in

moved in

this duct

black and

could be

the

don't

the

duct and

[Arthur]

A duct can be insulated inside or out.

this may help.

Don't tell me what I can understand, tell me what I can't mis-understand (Gen. Douglas McArthur)! No matter what you do you are a problem solver....what do you do? Arthur, Website:

Email: [e-mail]

[BJ Nash]

It would seem to be "Closed Cell Foam", a material that will not absorb moisture, commonly used to insulate ducts- either inside or out, maybe both. It is the same material pipe insulation is made of and still used today in view of a lack of a better material.

If it is wet in there, don't blame it on the foam, try to find where the wet is coming from!

High humidity can be a serious problem- once mold starts it can be very difficult to control. See

BJ