Opinion on new furnace duct install


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Old 12-11-16, 02:55 PM
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Opinion on new furnace duct install

I just had a new furnace and air conditioner installed and would like your opinion on how the lower ductwork of the return transitions to the upper ductwork of the return. The installers just used a straight rectangular section and angled it from the lower to the upper ductwork. Just for information, the upper centerline of the ductwork is approximately 2 inches offset from the centerline of the lower ductwork.

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Old 12-11-16, 03:36 PM
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I don't see a problem with the actual duct work but it doesn't look like they sealed it.
Are those seams leaking ?

Metal foil tape should be used to seal those joints.
 
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Old 12-11-16, 04:06 PM
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Pete, the joints are not sealed. Actually, there are some gaping holes where the metal was cut in order to assemble this together. Not a very professional looking install. Is it normal to use the foil tape on joints like this? I have a lot of joints in the system that do not have tape.
 
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Old 12-11-16, 05:40 PM
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Some folks use foil tape (use tape with UL 181 listing), other folks use duct mastic. With the mastic, you use fiberglass mesh tape first over large gaps and then the mastic.

The mastic is probably faster, but it is unbelievably messy. Wear old clothes.

A lot of older systems were never sealed; now it's a best practice.
 
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Old 12-11-16, 09:37 PM
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No excuse for gaping holes. Call them back.

Lots of people don't seal basement ducts. The laziness argument is that it is semi-conditioned space so not worth the effort.

I look at old systems and see tighter joints/seams than modern installs. They used heavier gauge metal and had amazing skill.
 
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Old 12-11-16, 09:38 PM
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don't worry about leakage on the return side - the panned off floor joists most houses have leak like crazy.

the only part of the return side you don't want even minor leakage is the connection between the filter cabinet and furnace.
 
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Old 12-12-16, 05:41 AM
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Thanks to everyone for the replies. So, are the holes/gaps in the return air ductwork nothing to worry about or should they be sealed? Attached is a picture that is representative of the gaps in the return ductwork joints.
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Old 12-12-16, 02:47 PM
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Why would you not want a properly installed system?? I presume the contract didn't mention sloppy work gets a reduced price. I would expect supply side and return side to be sealed. No exceptions. The furnace is not installed a conditioned living space, any air pulled thru that gap you show will reduce the conditioned air slightly and the furnace will need to heat that air.
 
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Old 12-12-16, 04:00 PM
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No need to "worry" about them but I'd seal them with foil tape like I mentioned.
 
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Old 12-12-16, 10:49 PM
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Holes like that shouldn't exist on properly install ducts. that's sloppy work.

The seams should be so tight that they barely leak at all, or leak just around the corners.

actual holes should be covered if not fixed. normal seams on return don't need to be sealed.
 
 

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