Sealing around duct work at output and return vents


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Old 07-07-17, 02:54 PM
J
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Sealing around duct work at output and return vents

Hello,

I've been replacing all of my output and return vents and I started to notice they all have a gap between the wall/ceiling and the duct work. Would it be worth my time and effort to seal these gaps? Would I just use foam insulation or caulk?
Here's a picture of one of my return vents. You can see the gap on the lower right side.
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Thanks in advance,

Jon
 
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Old 07-07-17, 04:04 PM
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You could get some foil faced tape, seal all your seams and bridge your gaps with that.
 
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Old 07-07-17, 09:26 PM
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Does duct tape fall under the category of "foil faced tape"?

And is it worth the effort of sealing those gaps? Will the HVAC system work more efficiently or effectively? Are those gaps really causing the system to lose air flow since they are at the input and output points?

Thanks,
 
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Old 07-08-17, 01:25 AM
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No, duct tape should never be used on any ducts. The name is a total misnomer. Foil tape is right near the bulk duct tape in the ventilation aisle. Maybe $5 a roll. You'll find a ton of other uses for it once you have it.

It sticks like crazy, esp to itself, but you'd need to at least use a damp rag to get any dust off the surface. I DON'T know how well it will stick to paint and joint compound over spray.

Boy, that is really some crappy ductwork install isn't it? In your pic it looks like they hand made (poorly) some sort of extension or boot.

All that said, you really probably aren't losing that much air since it will tend to flow right through the register to the suction point or out of the duct through the register to the room (in the case of a supply). You could be drawing some air and dust in the system if it's not sealed well, and if you try to shut a supply vent it will tend to blow in to the cavity, be it a wall or ceiling.

I like to see the duct at least come partway into the sheetrock opening if not flush to the inside. Ideally they'd all be flanged and attached to framing in the wall/ceiling. Of course that would cost $5 more each and no builder will spend that out of his pocket.
 
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Old 07-08-17, 06:48 AM
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I don't think it's as much about air flow as it is good workmanship. And maybe keeping mice, insulation, dust and other debris from getting sucked in so as to keep the system clean.
 
 

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