Reducing size of duct for range hood


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Old 09-05-16, 01:21 PM
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Reducing size of duct for range hood

I bought a NuTone Allure I Series 30 in. from Home Depot. This is the info from the description. "Convertible range hood can be installed as 3-1/4 in. x 10 in. (horizontal and vertical) ducted, 7 in. round (vertical) ducted and non-ducted." I live in mobile home with 5 inch duct, no elbows, and only about 5 feet vertical, through the roof. Everything I see says I can't reduce to 5 inch, because it has too much power. However, with a straight short vertical, would it be ok? If so, how do I reduce? If not, how do I close off my current duct to go ductless?
 
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Old 09-05-16, 02:57 PM
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i would not go ductless, You will have a reduction in air flow if reduced but would be much better than a ductless vent. Why not change all the pipe?
 
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Old 09-05-16, 03:28 PM
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I wouldn't opt for recirculation either. Since you are going straight up with no restrictions you should be OK.
I would try to keep the 5" section as short as possible, but leave enough to attach and tape the adapter.

I haven't used or seen a 7"-5" adapter, but definitely 7-6, so you should be able to find an adapter that works.

This can be frustrating to make the connections and you might want to purchase a tool like below, HD has them. You can crimp your connections to where they fit inside one another.

Name:  crimperduct.JPG
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Old 09-06-16, 04:02 PM
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Can I use Speedi-Products 10 in. x 3.25 in. x 5 in. Wall Stack straight Boot and duct tape. I don't want to cut through my roof.
 
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Old 09-06-16, 06:24 PM
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10" x 3.25" sounds like square duct. Where does the 5" come in ?

Do you mean a square to 5" round duct adapter fitting ?
That should be ok.

Instead of using duct tape.... use metal foil tape.
Nashua Multi-Purpose HVAC Foil Tape-1207792 - The Home Depot
 
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Old 09-07-16, 05:32 PM
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This is what I have.

Name:  duct.jpg
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Last edited by PJmax; 09-07-16 at 07:15 PM. Reason: added pic from link
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Old 09-07-16, 05:42 PM
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The adapter you linked to is perfect for what you need. Use metal tape as already mentioned.
It is much easier to connect the duct work before mounting the hood, you have room to slip one fitting into another and then mount the hood.
The hood should have included a 3.25x10" damper assembly, ensure you install one.
 
 

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