I am replacing my air conditioning/heating system with a geothermal system. Some contractors have told me that the vents in place now are air conditioning vents only, and that they must be replaced for the heating to also come from the ceiling. Is there a difference between forced air heating vents and air conditioning vents?

I am no HVAC contractor,but in laymen terms,Heat rises,cold falls,if you have vents on the ceiling or high on the walls,they are good for the A/C,If there are vents on the floor,they are good for heat and A/C as the heat goes up and around a room,A/C goes up and the down when cooling a room.

Tit for tat, But again,I am not an HVAC person,maybe they'll have a better description.

If you don't have problem with your existing system, don't touch the vents