I have a question on return ducts for the bedrooms in my house. We are having a convetional a/c installed in my 3 year old colonial style home next week. We decided after much debate on a 5 ton lennox single unit located in the attic which will supply the whole house(2500sq ft) in one zone. We live in New England and a/c is only used a few months a year so the return on 2 systems or even zoning was 25 years so we voted against it. The first floor will be supplied by four drops through closets on the second floor. The second floor drops will be in the ceilings as well. The proposal was for a return in the stairwell which I beleive will work great to remove the warm air from the first floor. The master bedroom is very large therefore will require a return as well. My question is that the other two upstairs bedrooms will have their doors closed 90% of the time and currently do not have returns designed in, all of the "experts" who quoted said that under the door air flow was sufficient, is it? Do i need returns in the two bedrooms upstairs? Will it make these rooms warmer not having returns? Thanks for the help