Window ac don’t buy by Btu alone. As a rule of thumb, an air conditioner needs 20 Btu for each square foot of living space, but there are other considerations, such as the height of your ceiling and the size of your windows and doorways that may create a need for more cooling power. To measure your room, multiply the length of the room by the width. Add together the size of rooms that aren’t separated by doors; the unit will need to cool both. Some people may not like the appearance of the indoor part of the system. While less obtrusive than a window room air conditioner, they seldom have the built-in look of a central system. There must also be a place to drain condensate water near the outdoor unit. Qualified installers and service people for mini splits may not be easy to find. In addition, most conventional heating and cooling contractors have large investments in tools and training for sheet metal duct systems. They need to use (and charge for) these to earn a return on their investment, so they may not recommend ductless systems except where a ducted system would be difficult for them to install. Professional team can do this for you so don’t be worry about anything which afraid you.