Exhausting an OTR microwave
Hello, just purchased a new Samsung OTR microwave to replace an ancient, dead GE Spacemaker which was set up for rear exhaust.
I'd like to also use rear exhaust on the new one, however when we pulled the old one off the wall, we found that the builders/installers (we're not the original homeowners) installed the exhaust duct offset about an inch to the side of where it should be (sigh...). The result is that the microwave will exhaust partly into the wall structure.
I don't see an easy way to fix this, other than completely re-doing the exhaust ductwork and the siding on the house. This is not an option right now.
So now I'm considering doing front exhaust (recirc into kitchen thru filter) on this thing. It does have a charcoal filter, but I'm wondering, how much filth will this contribute to the innards of the microwave over the years? Other than changing the filters, will it get disgusting and need to be periodically cleaned out?
Any other pros/cons to doing front/recirc vs. rear exhaust?
Also, does anyone know of any tricks to deal with the offset ductwork issue so that we could still use rear exhaust? I was thinking of blocking off the offset part but of course that would reduce the overall exhaust area by a good 10-15%, and could still end up leading to grease and crud buildup on the block-off plate, tape, or whatever I use to cover it.