With 9 1/2 ft ceilings, I wouldn't do anything that would mix the warmer ceiling air with the rest. With 9 1/2 ft ceilings; don't use a ceiling fan. Direct the airflow from A/C straight out never up.Keep any other fans low & blowing level at a low speed. The warm air at the ceiling acts as an insulator that slows down heat transfer, due to less temp differential between air & ceiling surface. Just my advice. Hey, thanks for liking the info on my HVAC Web pages. Make hard copies & put the info to use. I made an important change on one point on the "Trouble Shooting" page, so refresh & print the revision. - udarrell

Thanks ERL, I saw one at a builder that was 4.5 ft by 5 ft for a unit large enough to cool a 2400 sq ft house. I might do a split and have one 2 ton and one 1.5 ton so that helps if I go that direction. Bob

Also you don’t have to put the side flaps on. I have a small window upstairs and my 5,000 BTU unit just slides in perfectly without the flaps, leaving about ½ inch to work with that I seal up with the foam that comes with the unit and duct tape.

As I never depend on conduit to provide a good ground, I would run one green grounding conductor, splicing in branches as needed using proper conduit bodies or boxes for this purpose. Certain metallic conduits are considered adequate ground bonding methods. The number of neutrals partly depends on the requirements of the units. Those that don't require neutrals can be two wire (neither of which should be white unless color tape is used). Otherwise, each unit should have its own neutral because presumably some 120 Vac circuits are present in the device. Remember, all circuits are supposed to return currents to the box providing their protective device. If the protective device (circuit breaker) depends on measuring currents in the neutral, then a neutral should be run anyway. Also, a neutral can "future-proof" the circuit if your devices are replaced with others requiring a neutral. Read each unit's installation guide for requirements. Get a copy of the handbook form of NFPA 70 for further details. (In my opinion, this book is the minimum requirement for non-professional residential wiring that will otherwise only be inspected by an electrical inspector who can't see everything.)