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Discussion Starter · #1 ·
Hey Everyone,

Remodeling the kitchen and am putting a microwave over the stove. Want to vent it outside.

Questions:

Can I use Flex hose/dryer vent hose for this?

What is the largest hole you can pop thru a 2X8 safely?

What have some of you done??? I have the ceiling wide open down to the joists right now so I'd like to do it now before insulation and sheetrock.
Thx.
 

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Hey Everyone,

Remodeling the kitchen and am putting a microwave over the stove. Want to vent it outside.

Questions:

Can I use Flex hose/dryer vent hose for this?

What is the largest hole you can pop thru a 2X8 safely?

What have some of you done??? I have the ceiling wide open down to the joists right now so I'd like to do it now before insulation and sheetrock.
Thx.
You shouldn't use dryer duct for the microwave. It would help if you posted a picture of the area or described the situation you have. Is the exterior wall behind the stove/micro setup or will this need to be routed somewhere? If routed, be aware of the limitation as to distance you can go. Every turn you make reduces the ability of the fan to vent properly.
Ron
 

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The vent on that appliance (by code) must be a smooth metal interior. I have not done it any other way nor would I. Using a flex hose, would be like making one long grease trap. Most OTR microwaves require either a 3x10 duct or min. of 6" round. Either way notching or boring a 2x8 joist that size would not be allowed except in the rim joist. I believe the largest hole would be 2.5" but not in the middle 3rd of the joist. Putting in ducting that size (if you could find it) is not going to work. Two story house?
 

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Newbie Bill
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The instructions with the appliance should be pretty explicit as to the type and size of ducting required.

Some go so far as to help you calculate acceptable distances.
 

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Discussion Starter · #6 ·
Thanks everyone for the resonses. I will post pics as soon as I purchase the unit and see what size metal vent box I need. It is a 2 floor cape and I'm thinking I can go thru the roof (with regret hate going thru the roof for anything) There is a small closet above the micro wave area. It would be a straight shot....
 

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johnpma
I'v done this type of installation used a 3"x10" to 6"dia metal duct 90 than the 6" up thru the roof, make sure to insulate (fiberglass with foil) seal joints with fire proof caulk.

I had good luck with this for years, untile rerouting the exausting duct 10' out to a gable end wall (don't like holes in the roof) now I have some condensation problems wet insulation. It maybe because I had a leak in a joint blowing thru the fiberglass insulation. Repairing that mess now some how don't want to go back thru the roof.
 
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