A ductless air conditioning system has two parts to it, an indoor unit and an outdoor unit. The outdoor unit holds the condensing coil and the compressor. The indoor unit holds the evaporator and a fan, with metal tubing connecting it to the outdoor unit.
This really isn’t different than a standard AC system. What is different, however, is that the indoor unit is meant to be mounted on a wall within the building and not inside the furnace, usually on the top floor. Refrigerant is cooled by the outdoor unit and pumped up to the indoor unit to generate cool air. The natural convection effect of gravity ensures that the cool air makes its way down to the other floors. It’s a very simple system. In some ways, ductless AC is more efficient than regular AC because cool air doesn’t have to be pushed upstairs from the basement.
Unfortunately, consistently cooling every room in a house can be hard with a ductless system. Rooms with poor ventilation or that are closed off from the rest of the house won’t get cooled unless doors are left open and/or fans are used to push cooler air into them. Forced-air systems don’t have this problem because individual rooms have their own vents for receiving and returning air, ensuring that every room gets its share of the cool air generated by the AC system.
Ductless air conditioning is really meant for use in situations when a forced-air system won’t work. It’s not perfect, but it’s a lot better than the alternative.
