Some portable air conditioners are 7500 to 8000 BTU and can cool 150 to 200 square foot rooms
. These are the smallest and most economical of them. Some have separate cooling and dehumidifier functions and it is possible to select any mode. A timer, air filter, temperature display and three cooling/fan speeds are the different characteristics. For areas of more than 200 square feet, a unit of 9000 BTU is needed. These may have an ion generator. There are two sizes : 9500 and 11500 BTU that have multiple speeds and a remote control. A drip container holds condensation. Some units have a self-evaporating technology. A few have a capacity of 10000 BTU for a room of 250 square feet, a two speed fan, washable activated carbon filter to remove odor, a remote control and an 8 hour timer.