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The Basics of Window Air Conditioning Units

Where central air conditioning is not a feasible option, a window A/C is a popular choice to add cool comfort to one room or limited area inside a house. Though central units are efficient, these whole-house systems require ductwork. If ducts are not already built in to the structure, installing them is labor-intensive and costly. A window A/C is a far less expensive alternative with quick, straightforward installation and reliable cooling performance.

The function of a window air conditioner is essentially like a central system, except with all components installed in a single box. Here’s how the cooling cycle works:

  • An internal blower draws warm air inside the room into the intake grille on the front of the unit and then through the unit’s air filter.
  • Filtered warm air passes through the internal evaporator coil, where heat is absorbed by refrigerant, cooling the airflow. Refrigerant then circulates through the condenser coil, where absorbed heat is dispersed into outdoor air.
  • Cooled, comfortable air is directed back into the room through adjustable cooling vents on the front of the unit.

Sizing for Comfort and Efficiency

Both oversized and undersized air conditioners typically deliver substandard cooling performance and impose higher cooling costs. The cooling power of a window unit — known as its BTU capacity — should be appropriate to the size of the room where it is installed.

Air conditioner BTU capacity is expressed by “tons,” and one ton = 12,000 BTUs. To ensure the capacity of a window A/C is appropriate to the cooling load, the unit should provide about 20 BTUs per each square foot of the room.

However, factors beyond simple square footage also influence proper A/C sizing. That’s why installation should be done by a qualified professional utilizing industry-standard BTU-sizing software. Other circumstances that may affect sizing include:

  • Number of windows in the room
  • Proper air sealing around the unit when it is installed
  • Amount and quality of insulation in the house

For more about the selection and installation of a window A/C, contact Beyer Boys.