We are in the process of replacing the existing microwave/hood with a new one. With that I wanted to install ducts for outside venting. That means I would need to run a duct on top of the cabinets to the outside wall. The hood is not on the outside wall but about 4' to 5' from the outside wall.
The hood will be a microwave/hood combo again. Mainly due to space reasons. So no extrem professional usage.
Now the minium diameter that is recommended seems to be 6".
But I do not like the idea in running a 6' silver ugly metal duct above the cabinet.
So what are the options?

- Could I go with a 4" duct? That is easier to hide
- Are there any square flat ducts that would not be visible that much when they are flat on top of the cabinets? I have used plastic square ones in Europe for over 20 years. Without any problems. They were officially sold as hood ducts. But I cannot find similar ones here in the US.
- I don't really like the idea of covering the space between cabinet and ceiling with a board to hide the duct since I would need to do that on all cabinets.
- I also really can't run the duct inside since the cabinet above the hood is not high enough to provide space for the required square to round converter and a 90degree elbow on top of each other.

Any ideas how to solve this problem?

 

What behind the wall where the microwave is going?

I take it's open between top of the cabinet and ceiling?

 

The dining room.

Yes it is. About 1 foot of open space.

 

Ok, looks like you are kinda out of luck. but not totaly out of luck..


This what i would suggest..

Lay the 3 by 10 (I am drawning a blank the normal size venting on these unit) duct work on top of the cabninet.. I hope you have crown molding on top of the cabnet to hide the duct from floor view?

Duct that out to the side of the home..

Then tie the duct from the OTR into the duct going across the cabnet.