Gas and Oil Home Heating Furnaces - cool air return

We are finishing out the basement. There are forced air vents already in place for the rooms (heat and cooling). There is one cool air vent in place. Do we need to put in cold air returns in the other rooms?

Greetings,
You pose an interesting question. As an HVAC Designer my advise to people when asked this question is yes. If you can afford to do it, this in fact will be the ideal solution.
However in a basement situation it's not as much an issue as it is a desire.
When placing the return in the room(s) attempt to keep on the opposite side of the room from the supply. I assume you have ceiling registers, so make these returns as low as possible.
This way they will pull the heat off the ceiling in the winter and redirect the air flow in the cooling mode. Another benefit is you will better be able to keep doors shut in these rooms without impeading the HVAC system.
GOOD-LUCK
TIM G
HVAC DESIGNER
griffintimmym@cs.com