A window air conditioner is a common sight, particularly in older homes and unit blocks. This is primarily because they are a lot easier to install than split systems – everything comes in one box that sits on your window frame. You simply lock it in place and plug it in.
Window air conditioners are refrigerative air conditioners, which work by drawing warm air through the side of the unit then forcing hot air outside through condenser coils and cooled air indoors over evaporator coils. A refrigerant is used to cool the evaporator coils.
The major difference between these systems and split systems is output capability. Where a split system can be linked to many condensers, a window system features a single condenser meaning that it is great for single room applications but not whole-house cooling.
Installation requirements for window mounted air conditioners
When it’s time to install a window air conditioner, most people simply put it on the window sill, close the window and use that to lock it in place. It’s a simple method, and in most cases it works reasonably well. But it does mean that you can never open your window (or the unit will fall out) and on ground-floor windows that are facing the street, people can either steal the unit or use it as an entryway to your home.
These days window units tend to come with mounting brackets – which should most definitely be used, where possible. It's also a good idea to attach the side of the air conditioner to the window frame itself, to help secure the unit.
For permanent installations, people have been known to cut a section out of a solid-pane window and fit the cooler there. If you do this, make sure that you use caulk around the edges of the unit so warm air doesn’t infiltrate back in.