Upstairs readings with all other zones off All doors closed = supply air temp 56.9 All doors closed = return air temp 78.8 Temperature difference = 21.9 Supply air CFM all doors closed = 615 cfm Upstairs readings with all other zones off All doors open = supply air temp 50.2 All doors open = return air temp 74.7 Temperature difference = 24.5 Supply air CFM all doors open = 805 cfm Upstairs readings with downstairs zone on All doors closed = supply air temp 65.4 All doors closed + return air temp 74.1 Temperature difference = 8.7 Supply air CFM all doors closed = 267 cfm Upstairs readings with downstairs zone on All doors open = supply air temp 56.3 All doors open = returned air temp 75.3 Temperature difference = 19.0 Supply air CFM all doors open = 372 cfm I arrived for a previous customer air flow problem. I inspect the rooms that they were having issue with and found all the doors to be closed and the thermostat to be in the hallway in the top of the stairs. I inspected the s