I enclosed my dining room which has the central return located in that room. The central return is 22x22. I have one door (8x3 foot) with small space below door of about one inch. I will be placing 2 vents of 24x14 in the newly constructed wall. Will this be sufficient for air flow to the air handler or will it be causing the ac unit to stress and cause the coils to freeze. Also, is placement of the vents important as the central return vent is located near the floor as the vents will be about 9 to feet up on the one wall. Should I space the 2 vents apart or does it matter.