We just bought a 2 story zoned heating and cooling with 2 AC units and 2 furnaces. 1 of both for each floor. My question is about shutting off ducts off the main trunk, we have 4 bedrooms upstairs which are cooled off 1 AC unit, we only use the master bedroom. The others basically just have boxes at this point. I have read it is ok to shut off the ducts somewhere, and then another source saying it makes it harder on the AC unit. I would like to close them all except the ones going to the master bedroom and master bath.
We had the units inspected and cleaned and the HVAC guy said our units are very large for the house. I have no idea, I got the models #s and it looks like the unit for upstairs is a 3 ton Goodman which is newer and the older for the main floor is a 2.5 ton Rheem. The house is 3,100 sq ft.
Then AC unit upstairs is able to cool off the master to a nice temp in only 2-3 hours. I turn it on a few hours before we go to bed and turn it off all night and day just because I hate to cool the entire upstairs all day and night when it is not being used. and the temperature reading is taken out in the hall so it would have to run a while, we are looking to have it moved into the master bedroom or get a remote sensor.
I just figured if we shut off the other ducst we would get more air coming into the 1 space we need it and I could run it even less. Closing just the vents in the rooms doesn't seem like it would do much. Don't want to do it if it will hurt the unit though.