Thread: Return and Supply Ducts Touching

Forgive me if this has already been discussed . . . but since I had a recent discussion with another inspector, I see this arrangement installed frequently. The concern is whether or not having return air ducts and supply air ducts in the attic in contact with each other can cause condensation to form where they touch. If each has an R8 insulation value, is this a real concern? I haven't detected any wetness so far, but that may just be seasonal. Is this installation method frowned upon?

Thanks.

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As I recall, incidental contact is not a problem, however, in one photo a strap is broken and hanging loose, when properly supported the top duct should not be laying on the lower duct as that is more than incidental contact.

In the other photo the duct is being pulled against the corner of a piece of 1x which could tear the duct outer covering, that is not good.

Have an HVAC company come out and properly route and support the ducts.

Also, that short piece of 1x looks like it 'was' a lateral brace, but it is now doing nothing beneficial, the HVAC installer of that unit probably were the ones who cut it out.

Originally Posted by George Potter

Forgive me if this has already been discussed . . . but since I had a recent discussion with another inspector, I see this arrangement installed frequently. The concern is whether or not having return air ducts and supply air ducts in the attic in contact with each other can cause condensation to form where they touch. If each has an R8 insulation value, is this a real concern? I haven't detected any wetness so far, but that may just be seasonal. Is this installation method frowned upon?

Thanks.

George, some of the folks down Houston way get really into writing this up and it may be an issue there. I don't see ducts touching as an issue here since we tend to be much dryer for most of the year. When the ambient air is as humid as in Houston or other coastal areas, it may be a real concern with condensation an potential mold. Around here, I just pay attention to proper support like Jerry P. mentioned. If a duct is laying on top of another, then both ducts insulation is compressed and is no longer R-8 in addition to possibly restricting air flow.

J&J,

Thanks for the replies. As it happens, the other inspector IS from Houston. Going forward, here in the DFW area, properties with the incidental contact may just get a quick nod from me.

Never found a concern. Maybe and I say maybe, it might be a concern but most likely so minimal in hot humid climates I doubt it would be a concern there either. I lived right next to the ocean in florida and I never found it a concern with homes around there either.