Question

Why is it more effective for heater to be placed at the bottom of a room and cooler for freezers to be placed at the top of a room?

Answer 1

Because the hot air produced by heater rises up, so it's effective to place it at the bottom to fill all the room with hot air.
Cool air goes down since it's heavier than other air in the room, so we should place it at the top of the room.