Is installing a new return vent the way to go?

[Shellco123]

I am getting a new HV/AC system installed. Two of the guest bedrooms do not have a return, only supply in the ceilings in front of the windows. (both 10"x11" dimensions with 9" ceiling) The home is one story/slab. The rooms get REALLY cold in summer, and REALLY hot in the winter IF the doors are closed.

Question #1 - Is it ok to add new returns on the other side of the rooms to help relieve this problem? (Can't get into the walls to do floor supply.

Question #2 - I've been measured (by J load analysis) that I need a 4 ton unit - do I need to adjust if two returns are added?

TIA for answers, and other thoughts?

[wahoo]

Manual J figure would not be affected by returns being added. I see no reason you can't add returns in these rooms, but you're limited as to location, so have to do the best you can.

[skippedover]

First, you can never really have too much return air. If the load analysis shows 4.0-tons, so be it. Just make sure the designer has also inspected the duct system for tightness and to be sure it can handle 4.0-tons quietly.