Leaky return ducts


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Old 02-06-17, 02:34 PM
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Leaky return ducts

Hi all! So today I doing something in the office and dropped something by the return vent. Noticed some light as my wife was downstairs doing laundry.

So I did some investigating and found light in all of the return ducts! Not much but after going downstairs and looking I can sort of pinpoint the locations (will be hard to do because of the beams in the way) and see thats where all the duct connections are. Its solid duct but its at the corners and connections. Maybe the size of a pencil eraser, slightly less.

All my return vents ducts are located in the unfinished basement and go up to my single floor.

Im assuming I should seal these correct? What kind of risk do I pose to my system, if any if I seal them?

Also, what exactly are these leaks doing to my system (unfinished side is unheated, and I live in MA for reference?) unsealed? Do I potentially have the possibility to gain airflow out of my supply ducts?!?!

Thanks!
 
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Old 02-06-17, 03:03 PM
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Return air ducts are exactly that. They return cooler air from the lower sections of rooms to be recirculated in the heat chamber. Those air gaps you have pose no problem and are only sucking more air at each point. If you must, you can seal them with caulk or foil tape. No harm will be done.
 
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Old 02-06-17, 03:40 PM
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Gaps within the conditioned envelop of the building aren't so bad because it's just bringing in conditioned air like the air returns. It's worse if there are gaps in a crawl space or attic where it draws in outside air. For every bit of unconditioned air sucked in an equal amount of conditioned air has to be pushed out of the building above.

I would seal the gaps if you can. They are allowing air into the system that has not gone through the filter (unless your filter is right at the infeed to the unit).
 
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Old 02-06-17, 04:13 PM
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If the return ducts are leaking, then I'd bet the heat ducts are also. Those are the ones that will benefit by sealing.

Rather than caulk pick up a brick of electrical putty, it's like clay but will not dry out and you just pack it into the openings.

Then pick up a roll of mylar HVAC metalic tape (NOT THE GRAY DUCT TAPE) and you can use that to seal the joints.

Take one branch at a time and for a few dollars you will give your system a tune up.
 
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Old 02-06-17, 09:24 PM
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IN our new construction home (Syracuse NY) I went in after the HVAC sub contractor was done and spent a lot of time sealing the supply and return lines with tape, mastic and in a few cases spray foam. Whether that substantially improves the comfort or efficiency of the house ... I dont know but it makes me feel better.
 
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Old 02-07-17, 04:53 AM
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There is a product called duct seal that works well. That's not the brand name but just the name of the product. I buy it in a tub and use an old stiff bristled paint brush. It's a thick consistency so it can bridge gaps yet it's fluid enough that you can easily get it into cracks. Once it dries if forms a firm yet flexible (so it doesn't crack) seal.
 
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Old 02-17-17, 07:30 AM
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Would that be ok to be used around a pregnant wife?
 
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Old 02-17-17, 08:36 AM
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I never suggested you make your wife eat duct seal.
 
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Old 02-17-17, 09:51 AM
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However a side affect might be the baby born in a nice neat package.
 
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Old 02-17-17, 11:23 AM
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Ruthless. Absolute savages haha
 
 

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