Sealing gap between duct and the registers

[visoredge]

Hello,

WHen lifting up one of the metal registers in my bedroom, I noticed there was a gap where cool air could be felt coming into the space right before the heating duct comes up into the room. What should be used to seal these spaces?

[Toolpusher]

when you remove the register, you'll see whats called a boot.
That boot is nailed to floor opening. At the floor level,
So the register will fit inside the boot.

Or the boot is nailed inside the floor opening just below floor level. So the register will fit in the opening hole.

[mo-flo]

is this a mobile home or house?if it is a boot,you can nail it like T.P. said or bend a 1/4 in. flange over to seal it.You can also use silicone,mastic,foil tape,etc. to seal it up.

[Reliant Air]

foam-a-fill



















just kidding I would nail it where I could to close up the gap as much as possible and then caulk it. Don't use to big of a nail. you don't want to split your flooring.

[visoredge]

Thanks!
It's a regular home, not a mobile home...
I'll take a closer look @ the boot, then use mastic or caulking probably...

[dash]

Per testing by our utility,the similar gap at drywall,when ducts are in the attic,is 10 to 15% of the total cfm ,in leakage.