I vented my microwave oven to the outside. Tremendous improvement especially during hot summer days. Used the black vent available from Microwave Oven Vent
. NOTE: This vent does NOT rattle when you are driving down the road.
In the process, I partially cut through a horizontal support in the wall. FYI the support is just above the dining windows. The steps below are what I would do if I had a do-over and wanted to avoid cutting the structural member.
1. use hook to pull out board above microwave
2. support microwave and remove screws & bolts securing metal bar that supports the front of the microwave
3. unplug and remove microwave (two person job - lift rear of microwave to remove from rear mounting bracket)
4. redirect microwave blower to back of microwave (see microwave installation manual - available on line)
5. measure and mark blower exhaust position on 1 " thick plywood that's behind the microwave.
6 remove plywood and mounting bracket - cut out plywood for exhaust. Notes: there are wires behind the plywood. Keep track of where the long screws go.
7. hold plywood in place and mark cut out on RV wall. caution if you cut the wall here you will partially cut through a horizontal structural member (I did and made more work for myself).
8. remark RV inner wall cut out at least 2 inches lower than the original marks.
9. drill through inner wall ONLY at the two bottom corners.
10. cut up from the holes through inner wall only. if the cutting gets harder as you cut up you're starting to cut the structural member. STOP cutting up and adjust your total cutout downward. I used an angle grinder with a metal cutting blade, very messy. After you get the vertical cuts do the horizontal cuts and remove the cut portion of the inner wall. Cutting is difficult. Hard to get the cut pieces out. Be patient and go slow.
12. Remove Styrofoam between inner and outer wall and proceed to outside cut. From inside drill through the top two corners of the cut. Go outside the RV and mark the outer wall cut. Notes: There are no instructions with the vent.. The suggested vent's outside cut will be different than the inside wall cut. Same width - vertical cut longer. Be careful not to make the hole to large there is not much room for error. I cut a template from butcher paper and used it to to protect the paint around the cut. Cut out the paper and used clear packing tape to hold the template in place, I cut through the tape as I cut the wall. Cut and remove outside wall segment.
12. test fit vent install a couple of stainless steel screws to hold in place temporarily
13. put plywood in place. Check clearances you might have to make the hole bigger to complete the next step - install plywood and mounting bracket
14. use aluminum sheeting to fashion a duct inside the wall to direct exhaust from hole in plywood to the vent. I stapled the aluminum sheeting to the plywood and sealed seams with duct tape. Aluminum tape would be better.
15. when you are comfortable with your duct work install the vent using sealant and stainless steel screws
16. staple 1/2 thick soft foam around the hole in the plywood. Seals between microwave and duct
17 bench test exhaust fan. Mine was dragging and needed a minor adjustment
18 reinstall microwave and support (two person job). Plug in microwave
19 reinstall board above microwave,