Originally Posted by creed0265
Our contractor wants to install only two cold air returns in a 2400 square foot first floor. The homes I have owned before had a cold air return in every room. I find that houses with very few large returns are noisy and I would think less efficient in heating and cooling.
What are the design "best practices" for cold air returns besides the return size (square inches) being equal to the supply size?
To properly mix and move air in the home, it is important to have a return air in each room, except for rooms that code says no return like bath rooms laundry, and kit. If you have a bed with door closed and door is fit close to floor when heat comes on the hot air will pressurize the room and if air can't get out of that room the hot air will stop flowing because of the pressure.
As far as sizing of the ducts and opening. A furnace blower can develop pressure to blow air, but it can't suck air as good.So our duct sizing charts will tell us that return air ducts have to be larger than hot air ducts to move the same amount of air. A blower is like a water pump, A shallow well pump can only suck water 20 some feet but you can put 100 foot of hose on it and push the water. You need to have your system engineered out. Do you know how much air they are moving in this home? Paul