Window and Through-the-Wall Air Conditioners

Window or through-the-wall: the opening decides the design

Window units sit in a double-hung or sliding window, with side panels closing the gaps on either side. Through-the-wall units slide into a metal sleeve built into an exterior wall and move air front to back, because a window model's side vents would be blocked inside a wall. Measure the opening before you pick a design, and compare it with the minimum width and height in the listing.

Cooling capacity is quoted in BTU per hour. A rough rule is about 20 BTU for every square foot of floor space, nudged up for a sunny room, a kitchen or heavy use, and down for a shaded room. Oversizing backfires: the compressor cycles off before it has pulled moisture from the air, leaving a cool but clammy room. Three fan speeds is typical here, so look for a low setting quiet enough for a bedroom.

115 V or 230 V: the outlet the unit needs

Small and mid-size units usually plug into a normal 115/120 V outlet, but the largest capacities are often listed as 208/230 V. That means a dedicated higher-voltage circuit and a different plug shape, which may need an electrician if the outlet is not already there. Dual-rated 208/230 V units work on either supply. Also read the title for a BTU figure: a few items in this aisle are fans or fan heaters from the same makers, not air conditioners.

Questions about Window and Through-the-Wall Air Conditioners

How many BTU do I need for my room?

Start with about 20 BTU per square foot of floor area, then add for strong sun, a kitchen or several people, and subtract for a well-shaded room. Choosing a unit that is only slightly larger than the estimate dehumidifies better than a much bigger one.

Can I install a window air conditioner in a wall?

Only if the maker says it is built for that. Through-the-wall models are designed to sit in a wall sleeve with airflow routed front to back, while window models need open side vents that a wall would block, which can overheat the unit.

What does 115 V versus 230 V mean for my outlet?

A 115 V unit plugs into an ordinary household outlet. A 208/230 V unit needs a dedicated higher-voltage circuit with a different plug configuration, and the plug on the cord tells you which circuit it needs. If you have no such outlet, an electrician must add one.