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Discussion Starter · #1 · (Edited)
Long story short, I bought a 8inch exhaust vent to replace the undersized 6inch cap that was put to exhaust my range hood (installers used a reducer)

To my surprise, the flex duct is 7inch instead of 8inch like I thought. I was already up there and had the product so I snipped a few ringlets of the 7inch flex duct and stretched it over the 8inch exhaust, tucked taped it real good and put it back to together.

Any issues with what i did? Everything kosher?

Cheers
 

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In my opinion you need a reducer, with heat and or moisture, how long will the tape last and when will you check that and how often?
 

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Discussion Starter · #5 ·
In my opinion you need a reducer, with heat and or moisture, how long will the tape last and when will you check that and how often?
I don't understand the difference. I'd still be using tuck tape to secure the flex to the reducer.

All I did really was cut 3 metal rings of the flex to allow me to pull it over the 8" exhaust cap. There was about a 1"x1" gap opening which I tuck taped.

I know this isnt the ideal way to proceed (using a reducer) but are there any issues from doing it the way i did?

Also, are there any negative impacts of increasing the exhaust diameter? I know reducing the exhaust diameter is bad (louder fan, less efficient, etc.)
 

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It's your home. You know that what you did isn't the right way but you are willing to live with that. If you hired a contractor to install that duct and he did that would you accept it?
Is "good enough" your goal?
 

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I concur with Surferdude2 and Roughneck. I’ve only done two kitchen renos (my own), but I didn’t consider using anything but solid metal ducting. The referenced Home Depot plastic lined product wouldn’t meet code in BC (and probably most places), which states:

“Ductwork for range hoods and range-top fans shall be of noncombustible, corrosion-resistant material”

Chris
 

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If you think the code for residential ducting requiring solid metal ducting is tough, you should see what we had to do on commercial installations.

The duct had to be of heavy gauge metal and all seams are required to be welded and inspected. Then the entire duct from hood to roof must be enclosed within a 1-hour rated fire shaft constructed with double layered 3/4" drywall, all taped and mudded. Then there has to be a fire suppression system installed with fusible links to actuate when the temperature shows out of normal range and also provide a manual actuation pull station on the wall. That suppression system must be capable of turning the hood exhauster fan on if a fire is detected. Then it must be inter-connected to the HVAC system to prevent any possible smoke from spreading to other parts of the building.

No wonder that restaurant food costs so much!
 
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