Radiant heaters are available at the store for $50 ea and are much more efficient than forced air most of the time.

Reversable ceiling fans is only for ones with flat blades. Curved blades might have a reversing switch but it won't work right. Curved propeller type blades are much more effective and efficient but much more expensive

Opening the oven after cooking is a plecebo. It'll be radiant heat one way or the other