Return Air Register Duct in Basement

Dale Hanson is thinking of purchasing a condo in Champaign, IL. His inspector may have given him bad advice:

"I am purchasing a condo and the inspector said he could not find a return air duct in the basement.

Is it necessary to have an air duct in the basement?"

Dale, I assume you mean is it necessary to have a return-air register that puts basement air into the return air duct that goes back to the furnace.

If the basement is unfinished, the answer is NO. You have return air registers in rooms that have supply duct registers. 

If you're trying to put in 500 cubic feet a minute of heated air into a room, you need to vacuum out an equal amount of air. 

In an unfinished basement, there's usually not a supply duct. Sometimes an installer may cut a register into a main trunk line in a basement to supply a little air to temper the space, but there's no need for a return air register in that case.

There's probably enough leakage in the seams of the ductwork to account for a register!