Large range hood venting?

Konrad..just outside of Edmonton Alberta

10 years ago

Hi all...got a larger under the cabinet vent hood from Kitchenaid around 600 CFM with 8" square lip connection, [upward]. I'm going through the roof, sraight up about 8 foot with a new hole. [was going out to the side before 4 inch, can't go larger]. Instruction shows a 10 inch pipe going onto the 8 inch square lip on range hood. [see below]. I find 10 inch overkill going all the way up, thinking to reduce to 8 inch, connect with 10 inch reducer to 8 inch...what would I loose on CFM?

Hate to put a 10 inch hole for our cold winters...I was looking for 10 inch ducting material, baffle etc. at home depot, lows, rona, nothing around, most are 6 inch, and very little 8 inch, wondering where the pros get their stuff.

Showing 8 inch square connection..isn't it odd go with 10 round over this square ?

Featured Answer

PRO

Anglophilia

10 years ago

There should be a flap up there someplace that closes when the fan is not on. You don't have cold air coming in from the outside. It's usually best to follow manufacturer's installation instructions.

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Comments (9)

Konrad..just outside of Edmonton Alberta
Original Author
9 years ago
Yes...I called it a baffle, probably the better term is backdraft damper.

Question...has any of you put in a 10" exhaust pipe for a 600 CFM vent?
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Lisa
9 years ago
last modified: 9 years ago
We almost put in one that big. Our hood goes up to 715CFM and we were planning on putting this vent on the roof: https://www.amazon.com/dp/B001E6FO2I/ We have a 8" round hole in the top of our hood, so were still only going to use 8" ducts though. We bought it and it was quite big.

However, we don't have anything in our house for "Make Up Air", which I think you should add when you have more than 400 CFM. We have an option to limit the fan to lower CFMs, so we decided to do that instead, and go with a smaller roof vent, to keep things safe and simpler. We ended up using the smaller version of that vent instead, which I think goes up to 600CFM or high 500's. https://www.grainger.com/product/DAYTON-10-23-64-x-6-1-2-Aluminum-45PE68

We got some of the supplies for installing the vent at Grainger and some at Build.com. Grainger is more expensive, but sometimes that is the only place we could find things.

I don't know about going round from square, but I do think having the air go through round duct work is probably more efficient from what I've read.
practigal
9 years ago
Yes, if you have an open fire place you should be particularly concerned about the make up air concept. When a 600 CFM hood begins to go full blast it can really pull a lot of air from the rest of the house and that can be extremely dangerous because the most obvious place for the air to come from is down the chimney which could result in pulling the embers from the fire out across the floor towards the hood.… Please take the time to learn about make up air.
Konrad..just outside of Edmonton Alberta
Original Author
9 years ago
Up to 600 CFM I don't need "Make Up Air" according to our regulation, that's why have chose this one, no fire here. This makes sense Lisa!
User
9 years ago
last modified: 9 years ago
Anything over 400 cfm needs make up air. Everywhere. YOU will need Heated Make Up Air. Canada is FAR more rigid in their enforcement than the US on that.

And you need 8" minimum duct for that hood.
Konrad..just outside of Edmonton Alberta
Original Author
9 years ago
Well...I was told by the seller, [Trail appliances] ...didn't do the homework, [ could return it] not worried, my leaky open house 4 rooms can handle and will crack the window open for this little time when cooking with electric.

Looks like Sophie knows it all....can you please provide a link for Alberta or Canada regulations?
User
9 years ago
CSA B149.1-10 is one of the codes covering that.
Konrad..just outside of Edmonton Alberta
Original Author
9 years ago
That's not a link but it will get me to gas fired chimney code. Just wondering where you get this info.