We recently purchased our first home in MA near NH border. The house is a cape built in 1965 with window dormers in front, shed dormer in rear. No attic, crawl space is about 16" with lots of blown in insulation. An addition was built in 1990 which was a foyer connecting addition to side of existing house with two car garage and large room above it. Off of the foyer is a 3 season porch. The heating source is a oil burner with forced hot water and no existing air conditioning system or any duct work.

Through my novice research, I was thinking that a high velocity mini-duct system would do the trick.

Have called several contractors that were referenced from spacepak and unico that also did traditional central air to find best solution. Two contractors have come by, two more scheduled for later this week, waiting to hear from another.

Both of the contractors said I do not have the space to run any ductwork in the original 2nd floor to do either traditional AC or hi-velocity AC. The first professional sais that to create space for duct work would become price prohibitive.

The family room above the garage has vaulted ceilings with crawlspace running the outside of the side of the house.

They both suggested a mini-split system for the master bedroom and one for the family room upstairs and central air for downstairs. They both recommended the Mr Slim systems by Mitsubishi. Upstairs has a laundry room off a hall way that connects the family room to the second bedroom and there's a small full bath between the two bedrooms where the original stairs went.

Downstairs consists of the foyer which has a full bath next to it and leads to the 3 season porch in the back, the stair case to the family room over the garage on the right and the kitchen on the left. The first floor of the original house consisted of a living room to the front left, dining room to the front right, bedroom/office to the rear left, kitchen to the rear right and a half bath in the middle of the back hall connecting the different rooms.

There is a full unfinished basement where duct work could be run for the first floor.

The price of doing central AC downstairs and the two mini-split systems upstairs is higher than what I was planning on spending. I'm not opposed to doing it right, might have to wait a year or two for that solution.

After finding this site and reading a bunch of posts I was wondering about other split systems (Fujitsu, Daikan...) that one could attach several indoor units to one or two compressors. I don't think we need to cool the dining room and living room. For the 6 to 8 weeks we really need AC, we can live in other parts of the house... Downstairs, I would like to cool the office, kitchen and three season porch. The office has a door and can be closed, same deal for the three season porch. If we put another unit in the kitchen, will that work ok? The kitchen opens to the foyer, the hallway and there's two pocket doors that separate the kitchen from the dining room. The three season porch can has two french doors leading to it and it is all sliding glass doors on the outside "walls".

Should I go with a central air system downstairs and two mini-splits upstairs?

Would a system with all mini-splits work on the rooms I would want cool work?

Or is there a better solution?

BTW, the first guy spec'n out the house measured room by room dimensions (including windows in each room). The second guy measured the inside dimensions of the entire house then measured the windows. Is there a right way and a wrong way or will they both work?

Thanks in advance for any help or suggestions or links to educate myself more...