Venting a Microwave/Range Hood Outside

jmai14 · 10-23-2011, 07:32 PM

Hey everyone. I received some very helpful advice before from this site and hoping to be so lucky again...

I'm in the process of remodeling the kitchen. My question is in regard to the new microwave/range hood we bought to go over the gas range. We moved the range hood to a new location in the kitchen, so the old air duct which vented outside is no longer in the right place. Basically I'm wondering how to set up a new air duct in the correct location. And how difficult will this be? (I have decent general handyman skills but have never done this specific type of work before) What supplies will I need?

The new location is right up against an exterior wall, so in terms of projects like this, it should be as easy as it gets. I'm guessing it's something along the lines of cutting a hole in the wall with my reciprocating saw, installing a pipe or duct, placing a vent cover on the outside wall, then finally installing the microwave (assuming drywall is back up). The studs of the wall line up about as well as I could hope for; the microwave is 30" wide, the first stud is from 7"-8.5" and second stud is from 23"-24.5" ... so the space between studs is pretty close to the center of the microwave location.

A follow up question is what should I do with the old vent? Would it be okay to just leave it in place and cover it up with drywall?

**oh'mike** · 10-23-2011, 08:13 PM

If you know the EXACT location of the new micro wave will be --your idea will work---

this is best to do after the cabinets are up or you may locate the opening in the wrong spot.

nice heavy microwave vents are available for 2x4 stud walls.

Before the cabinets go in--check for studs and wires in your way---You may need to 'header in an opening ' to locate the vent where you want it.

Another option is to have the vent go up into the cabinet above---and use a 3 1/4 x 10 addapter to 6" round and exit with a round vent.---This makes a waste of the upper cabinet,however and requires you to make a wood cover to hide the duct work.

jklingel · 10-24-2011, 08:40 PM

be careful w/ the cfm on the vent motor. some of these 800+ cfm fans cause negative pressure issues. if your house is super-tight, you may need to install a make-up air vent as well.

hellothere123 · 10-29-2011, 03:24 PM

I opened an old vent when installing a new micro/range hood...Then in winter I had a huge ice dam on the roof where the vent was - it created a leak...for some reason I had trouble sealing the outside vent, so I closed it up and switched it to use the internal filter to clean.

I probably use the vent part about 1 time every 10 years, so it made sense to do it this way.

sweaty · 11-01-2011, 06:23 AM

With the old hole, I would seal it up with expanding spray foam.

Ron6519 · 11-01-2011, 07:33 AM

The plan you have for the new installation sounds fine.
You didn't mention the electric, so I guess you have that covered.
The old vent hole should be completely closed, both the exterior and the interior. You want to eliminate any openings in the house you don't need.