Heater duct insulation ...question

Insulation appears dirty on the ducting. Customer wants
to if there is an acceptable insulation that is covered with a plastic
jacket…like what I see on insulation in attics.



Most of the ducting you see in attics nowadays are flex duct with the plastic on the exterior. It is quite common to see sheet metal ducting with plain fiberglass wrapped around it. If they are going to replace the insulation, I would recommend they pookie all the seams before installation.

Is “pookie” a local term for “high velocity mastic duct sealer”?

I am telling my age here but that insulation was typically use on systems that had central heat only. A/C was added at a later date the insulation should have been updated with the addition of A/C

Exposed fiberglass insulation over sheet metal duct was a common installation here in CA Charley. You will find this on original equipment (combination heating and cooling equipment) installed in the 70’s, 80’s and 90’s. Most FAU’s are now installed in attics for modern construction.

David - the insulation can be replaced, but this is really a “non-issue,” other than being “ugly.” As Steve suggested, the seams should be sealed to reduce this effect, or the insulation can be replaced with a foil-wrapped insulation.

I always said Ca was back asward in what they do if ya see that kind of insulation in mid west it spells old even older than me

Brand name.

That hard pipe ducting is actually good to have. Sealing the joints is what is needed to reduce air leakage. The black on the insulation is from air movement. The fiberglass acts like a filter. If it is loose you can use some spray adhesive to secure it back to the duct. If this is in the garage and the drywall is being used for fire separation the insulation should be pulled out of the space between the drywall and the duct and be replaced with fire foam.

I agree with Jeff, I see exposed fiberglass insulation over sheet metal ducting quite a bit and is typically not a concern. It’s hard to tell for sure, but in this photo it appears that the ducting is resting up against the vent piping. I understand that the standard minimum air space clearance from combustibles for a type B double wall is 1”, and 6” for type C vent single wall, I also understand that fiberglass insulation is not considered a combustible material, but is this not a concern that it may be resting up against vent piping.

Any vapor retarder belongs within the warmest third. If it is a heating duct then any plastic belongs against the ducting, not the exterior even though this looks better and is most common. This methedology takes on different forms depending upon the temperature of the air being ducted and the temperature of the air the ducting is running through.

Thanks everybody for the feedback…

Here in Georgia, all ductwork insulation had to have some kind of vapor seal when installed (ie: Foil or vinyl) on ductwork in any surrounding unconditioned space. All sheetmetal ductwork joints must be sealed as well. In the late 60’s and 70’s I used Long fiber F/G insulation with foil backing, and all joints were wrapped with asbestos tape. By the 80’s we were using a combination of Sheetmetal, Ductboard and flexduct. By the 90’s, and going forward we used foil tape and/or mastic on all joints, and again all duct insulation should be vapor sealed. In any inspection I do, I would state that existing insulation of this type, and condition should be removed, joints sealed, and new insulation added to meet today’s energy standards and requirements. IMHO