Room Air Conditioner Manuals & Owner Guides

Room air conditioner types

Conventional window unit

A one-piece box that sits on the sill with side curtain panels filling the gap. The most common and least expensive style.

U-shaped (window-straddling)

Splits into an indoor and an outdoor section joined by a channel; the window sash closes into the channel, which blocks less light and reduces indoor noise.

Saddle-style (sill-straddling)

Rides over the windowsill with the compressor section hanging outside below the sill, leaving more of the window clear.

Through-the-wall

Slides into a permanent sleeve in an exterior wall. Models without side louvers exhaust heat only through the rear grille and must not be used in a window.

Room heat pump (reverse cycle)

A window or wall unit that can also run its refrigeration cycle in reverse to heat, efficiently in mild weather.

Choosing the right capacity

Bigger is not better: an oversized unit cools the air quickly but shuts off before removing humidity, leaving the room cold and clammy. Use the ENERGY STAR sizing chart as a starting point.

• Heavily shaded room: reduce capacity by about 10%.
• Very sunny room: increase capacity by about 10%.
• More than two regular occupants: add 600 BTU/h per additional person.
• Kitchen: add 4,000 BTU/h.

CEER, voltage and running costs

The combined energy efficiency ratio (CEER) is cooling output in BTU/h divided by power input in watts, adjusted for standby power. A higher CEER means lower running costs. Annual energy figures on certification labels assume 750 hours of cooling per year.

Most units up to about 15,000 BTU/h run on standard 115 V household power. Larger units usually need a dedicated 230 V or 208 V circuit with a matching receptacle — check before you buy.

Room Air Conditioner FAQ