That's why you need to get a load done ... I have done well insulated spray foam houses out to 1k sf per ton ... is the current system working. Adding vents does not increase SF -- it actually allows what you have to work better. If you unit can cool and heat the space with vents .. you don't want or need a larger unit.
"the way we always do it" .. will get you an oversize unit.
It heats fine, definitely better on the more open side of my house though. I'm pretty sure that problem is with the duct work though. One side of the downstairs is the living room, den, kitchen, 1/2 bath and computer room, which is all all a fairly open area and heats fine. The other side is 3 bedrooms and a bathroom that is always several degrees cooler in the winter. In the summer it seems to cool that area fine though. This last guy also stated that I most likely need a 2nd return because I only have 1 16"x20" return currently.
