Microwaves that vent to the outside force the air through duct work to the outdoors.
Can all over the range microwaves vent outside.
When considering venting in an over the range microwave there are ducted vents and recirculating vents.
In the first example the microwave over the range otr will vent through the manufacturer installed grease or carbon filter then directly through an exhaust port that is ducted to the outside of the structure.
Microwaves over the range otr typically vent in two different ways.
If you have an over the range microwave it should have an exhaust fan that vents to the outdoors.
Many times an over the range microwave that recirculates cooking fumes can be converted to exhaust to the outside.
All over the range spacemaker microwaves can be vented to the outside using an equivalent total of 140 feet of rigid 3 1 4 x 10 rectangular or rigid 6 round ducting.
This eliminates smoke cooking odors moisture and hot air from remaining in the kitchen.
After the smoke and steam are removed the filtered fan vents the air outside your home or cleans it before releasing it back into the kitchen.
Over the range microwaves can vent to the outside or can recirculate the air.
When a microwave is replacing a standard range hood it is usually best to use the existing venting method.
Ultimately the goal of the vent is to pull the air from the microwave and deposit it to the outside.
If rectangular ducting please note.
Typically there might be a cabinet installed over the microwave and inside that cabinet will be duct work or a soffit above the microwave or a direct wall exhaust.
For this reason vent ducts are the only choice.