Central air units are commonly used in large buildings or malls, and are ideal for cooling a whole house. Installing separate units in each individual room can run up cost quickly, so if you plan on keeping multiple rooms cool, we highly recommend installing a central unit. Usually placed outside and behind your house, the unit consists of a condenser that collects heat from inside your house and turns the moisture from the heat into a liquid. Much like a refrigerator, it then sends the liquid up to the coils, which evaporate the liquid, making cool air. A fan then pushes that cool air throughout the house's ducts, effectively providing a cool safe haven from those hot summer days.