[daveblt]

HI'
When you vent a microwave to the outside the advice is to use a 31/4"x10"x6" stack boot.It seems the way the boot is made that the flap from the microwave damper hits the sides of the boot when you turn on the fan not allowing for full opening of the flap, maybe it will open a little less than halfway .If you bend the corners of the flap quite a bit then it will allow for full opening .Is this a usual practice to bent the flap or not ? Also it seems if you use a 4"x10"x6" register boot instead there is plenty of room to allow for full opening . Let me know your thoughts on this .

Thanks

 

[Chris616]

Never having used one of these it has taken me awhile to figure out that you’re probably installing an “over the stove combination microwave oven and vent hood”. Please give us a link to the installation guide, or at least the brand and model number, so that we can review what the manufacturer suggests.

I would think that bending the flap on the microwave exhaust would impact its ability to prevent the backflow of cold outside air.

Chris

 

[daveblt]

Yes ,over the counter microwave .The outside vent does close when the microwave fan is not on.


https://images.homedepot-static.com/catalog/pdfImages/7c/7c978e60-fac1-4aba-997c-90690d65ab7c.pdf

 

[Chris616]

Your description of the problem makes me think that you have omitted item “F” in the diagram at the top-right of page 11. I’d hazard a guess that the reason they specify a minimum 3” for that piece is specifically so that the opening flap of microwave doesn’t hit the sloped surfaces of item “E”.

Chris

 

[SPS-1]

You got this covered ? Page 11

 

[huesmann]

I actually located my transition at the top of the cabinet, with a rectuangular-to-round 90º elbow.

 

[daveblt]

Thanks for the info .I never saw this extension used in any videos on youtube so I missed this step .

Dave

 

[Calson]

Venting a microwave to the outside is optional and not required by code. Go to any restaurant and you will not find their microwaves vented to the outside. Same with the microwaves in aircraft.

 

[huesmann]

Many folks use an over the range microwave, which should be vented outside. Vent to room is just a waste of time.

 

[Nealtw]

Many folks use an over the range microwave, which should be vented outside. Vent to room is just a waste of time.

It does go thru a filter.

 

[huesmann]

Which doesn't do very much.

 

[Nealtw]

Which doesn't do very much.

Depends on what is being cooked I guess, I have had a friend complain about the fan and then I removed a 12year old charcoal filter, full of grease or oil.

 

[huesmann]

I mean, after 12 years it's bound to pick up something!