Chosen Solution
I recently changed the vent from recirculating to venting outside. It is now heating slower. What could do this?
The difference is the position of the fan and the vent. The vent contains a damper that opens with the air pressure. I have installed these and found I did not position things properly and the damper never opens. These vent are not part of the heating process, they just exhaust cooking fumes from the range below. However, if trapped, they may circulate in the oven and lower the temp of the food.
