Options for Ducting OTR Microwave

In the process of remodeling kitchen in our fixer-upper, and we've picked out a nice over-the-range microwave.

What used to be there was a typical old in-wall exhaust fan with chain, just inches above the stove, blowing everything directly outside.

I've removed all of the old exhaust fan except for the outside hood, which is there to prevent critters and water damage, of course.

My question/problem is that I need to make a new duct for the microwave, which is going to be placed directly above the old location of the fan. Being that the house has asbestos shingles, I really don't want to have to cut through that.

If at all possible I'm wondering if there's a way I could use some sort ductwork in the wall that would bring the microwave exhaust down to the existing cutout, so that I can vent the exhaust through the hole which already exists. I know some cosmetic work would be involved, but I'd rather do that than cut yet another hole in the siding. From what I hear, that stuff is not only dangerous, but wreaks havoc on your saw blades.

Thanks!

 

I think that some microwaves have rear exhaust knockouts as well as top knockouts. How would that work? Maybe an off set duct out the back to the wall opening.

 

To add. The microwave blower can be rotated to vent out the back, directly through wall.
Duct size is 3.25 x 10.
So to make your transition down, you will need a length of 3.25 x 10 duct, a 3.25 x 10 right angle fitting, and make or purchase a 3.25 x 10 end cap.
You will have to line up and cut the hole in the duct yourself to accept the round duct into the back of vertical duct. After duct is ran, the open wall can be repaired with drywall or add a piece of plywood behind microwave.

 

Yes, thank you both.

To update, I've opened the box, read the instructions, and flipped the exhaust around to the back. The instructions state that the ductwork may include no more than three bends, and should not exceed 10' in length.

Unfortunately, there is a stud smack-dab right in the center of the exhaust port, which means that in order for me to do this, I need to remove about 2 ft of the stud, which means I have to tear out a section of the wall, and build new framing to accommodate the ductwork. Not only that, but it's the ONLY stud within reach of the bracket they give you, which means that I have nothing to mount the bracket to. Oy!

 

At what stage are you in the remodel? Are new cabinets going in?
Ideally you will want to open up the wall floor to ceiling and shift/add studs to the outside of the duct area. Use the exterior wall cap as a center line to add studs.

 

I had run the electric put up drywall, and kinda half-a$$ed put up the upper cabinets to see how they look, but haven't yet tiled, so it's not TERRIBLY inconvenient. I mean, it's a pain, but could have been a lot worse.

Fortunately, this is not load-bearing, because the kitchen is in an expansion room. Still don't know where the original kitchen was (house is supposedly from 1900, although we suspect older).

Oh yeah. As a side note, I had stopped into a big box home improvement store the day after I posted this (still hadn't opened the box) and asked about the ductwork. I was told, "No, you can't have any bends in the duct. It has to go straight outside." As I mentioned above, the instructions tell a different story.