I am finishing my basement and would like to know where is the ideal placement of cold air returns in a basement, near the top of the wall or the bottom. Only one return was put in and I would like to add one or two more registers (the space is about 1200 sq feet). Does this affect the rest of the HVAC system in the house (air flow capacity, circulation, etc.)? Also, due to joist and window placements, is it acceptable to leave the cold registers in the ceiling, even though the heat registers are also in the ceiling. One last thing, I am also adding a room in the basement, does this room require a cold air register (by code)?
Answer:
Every room in the basement (in particular) should be serviced by a return air duct because as air cools, it falls and it cannot go lower than the basement floor so it has to be picked up there and returned to the system for re-heating. Cold air returns in the ceiling are nothing but decoration. All grills, hot and cold, should be at floor level.
