I'm in a 4 BR house and am having issues with uneven cooling in the bedrooms. The bedrooms area has its own 2.5 ton unit w/the lower two levels having a 5 ton unit.
I posted a few years ago about it and wound up having manual dampers installed which improved the situation slightly but didn't remedy it.
I've had a few HVAC guys come in recently and I've basically been recommended to install returns in each rooms since my returns are currently undersized.
The system is all flex and currently it's a 10"+8" return.
They suggested the following
MBR/Bath - 500sf - 12" Flex Supply (6"+6"+7"+7"+4") / 12" Flex Return
BR2/Bath/Hall - (BR2=200sf) - 10" Flex Supply (7"+7"+4"+4") - 8" BR2 Return + 8" Hall Return
BR3/BR4/Bath/Foyer (BR3=200sf/BR4=160sf) - 10" Flex Supply (7"+7"+7"+4"+6") - 8" BR3 Return + 8" BR4 Return
The hall leads to stairs and an open 2 story Foyer and downstairs has a separate unit
The bedroom doors will usually be closed which is why the per room returns were suggested.
I had a few concerns that I wanted to run by you guys before giving them the go-ahead
1) I looked up CFM for flex duct and it seems like BR2/BR3 with baths(7"+7"+4") will be getting 255 cfm but the 8" returns will suck 160cfm back. Should I ask them to use 9" returns for those two rooms instead?
2) The Vaulted Foyer area accumulates a good chunk of heat rising up from downstairs. They did not mention a return in the Foyer area, should there be one?
I'm only having them work on the upstairs unit, should I have them install an extra return from the top of the Foyer area to the downstairs unit since that's where most of the hot air originates?
Also for reference this is a relatively new home (under 5 years old)