Our house has central air, with the air distributed via flex ducts around the house. On the second floor, the diffusers have baffles behind them that can be closed when the system is not in use, but the mechanism on these devices isn't very well built and on some has actually broken.

I'd like to replace them, but I'm not exactly sure what to call all the parts. On the outside is what I would call a diffuser, but that's attached to some sort of plastic collar that (a) houses the baffle and (b) attaches to the flex duct via a long zip tie.

The whole assembly is clamped onto the ceiling via screws that connect to a little plastic "wing" that swings out when everything is tightened.

I'm not sure where to find these assemblies. The local Home Depot carries diffusers, but they don't have anything like the plastic collars with the baffles, and my Googling to date hasn't turned up the right thing.

I suspect part of my problem is that I don't know the nomenclature. I'm hoping you folks can help point me in the right direction.

This is the collar:

Collar that attaches to flex duct

This is the diffuser:

The diffuser

The screw holes on the diffuser match up with channels in the collar.

  • 1
    I think a picture would help a lot.
    – BMitch
    Oct 27, 2011 at 21:51
  • Possibly. I will try to add one later this evening. I was assuming that this was a fairly standard way of terminating flex duct.
    – larsks
    Oct 27, 2011 at 23:07
  • I think it is pretty standard for flex duct, but flex duct itself isn't as standard. Most of us are still on rigid duct work since that makes more sense in new construction.
    – BMitch
    Oct 28, 2011 at 13:17

1 Answer 1


It's a butterfly style diffuser damper. Home depot sells them, but I don't see one that has the long collar that you would want to attaching to the flex tube.

Your best bet is finding an online retailer that supplies parts for the flex duct systems. I see this one from a google search that includes the grille and damper box:

enter image description here

  • That turned out to be exactly the right thing...in fact, these seem to be a slightly newer version of what was already there. Thanks!
    – larsks
    Dec 20, 2011 at 17:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.