If you are mounting your air conditioner near the corner of a room, look for a unit that can direct its airflow in the desired direction for your room layout. Large room units rated at 120 volts may require a dedicated circuit and room units rated at 240 volts may require a special circuit. The standard household receptacle is a connection for a 120-volt branch circuit.

Room units operate on 120-volt or 240-volt circuits. Verify that your home's electrical system can meet the unit's power requirements. Other important factors to consider when selecting an air conditioner are room height, local climate, shading, and window size. The reason: an oversized unit will cool the room(s) to the thermostat set-point before proper dehumidification occurs, making the area feel “clammy” and uncomfortable.' A small unit running for an extended period operates more efficiently and is more effective at dehumidifying than a large unit that cycles on and off too frequently.īased on size alone, an air conditioner generally needs 20 Btu for each square foot of living space. In fact, a room air conditioner that's too big for the area will perform less efficiently and less effectively than a smaller, properly sized unit. Buying a larger capacity room air conditioner than is required won't make you feel more comfortable during the hot summer months. Proper sizing is very important for efficient air conditioning. A common rating term for air conditioning size is the 'ton,' which is 12,000 Btu per hour. The required cooling capacity for a room air conditioner depends on the size of the room being cooled - room air conditioners generally have cooling capacities that range from 5,500 Btu per hour to 14,000 Btu per hour. Sizing and Selecting a Room Air Conditioner The higher the EER rating, the more efficient the air conditioner. When buying a new room air conditioner, look for the ENERGY STAR label. The EER is the ratio of the cooling capacity (in British thermal units (Btu) per hour) to the power input (in watts). Energy Efficiency of Room Air ConditionersĪ room air conditioner's efficiency is measured by the energy efficiency ratio (EER). The largest models require a dedicated 240-volt circuit. Larger room air conditioners (i.e., those drawing more than 7.5 amps) need their own dedicated 115-volt circuit. Smaller room air conditioners (i.e., those drawing less than 7.5 amps of electricity) can be plugged into any 15- or 20-amp, 120-volt household circuit that is not shared with any other major appliances. For ways to save on cooling costs with a room air conditioner, check out our Energy Saver 101 Infographic: Home Cooling. Since they cool a smaller space, room air conditioners are less expensive to operate than central units, even though their efficiency is generally lower. Room or window air conditioners cool rooms rather than the entire home or business.

Window a c unit calculator