What size return air vent?

[dragonfly]

I am going to have my central air and gas furnace units replaced. We believe that the furnace is over 30 years old and not too sure about the a/c. Anyway, it's time for a new one. The man that is going to replace it all suggested that he put in a new return air vent and seal off the old one. He thinks that it is too small for the house. Currently we have a 12 x 20 in the wall and he would like to put in a 20 x 20 in the ceiling. Our house is 1450 square feet. Any input on this? Does it sound necessary for better air flow or is he trying to get more money?

[Ed Imeduc]

You dont say what size unit heat and cool you have. That is what will tell you what size you need Its just some in what size grill you have for return. The main thing is what size duct goes back to the furnace that counts. Now if you have a 12 X20 cold air duct thats 240 sq" very good for a 3ton AC going to the furnace . Just rough size is 60 to 80 sq" per ton in the duct for AC .Yes the filter should be bigger like that 20 X20. If your up north you can keep the filter intake grill down low. If you more down south better for the grill to be high to take the heat back to the AC. Do get 3 bids for the job.

ED ;)