The first step is to make sure you're using right-sized air conditioner. Your A/C should have enough capacity to cool the room and have a dedicated outlet with the proper amount of electrical current.

The next step involves proper securement. The window and window frame in which the unit will be mounted should be in good condition. The A/C should be braced from underneath with metal brackets, mounting rails or similar supports, or firmly fastened from inside with supporting angles. The metal brackets and angles should be attached to the exterior of the building and be strong enough to support the size and weight of the unit.

Anything used to adjust the position of the air conditioner, such as shims, should be independently secured to prevent shifting caused by vibration, wind or ice. The air conditioner should remain in place when the window is opened, or secured so that the window cannot be opened accidentally. Tilting the unit for drainage is okay as long as it isn't at a steep angle.

Dangers come not only from an improperly secured air conditioner, but also from any loose objects used to support it. Bricks, wooden blocks, phone books or videocassette tapes should never be wedged between an air conditioner and the window sill. Items such as flower pots, satellite dishes and bird feeders should not be placed atop an A/C, either.

Aside from these general guidelines, there are factors specific to each installation, such as the size and weight of the air conditioner, the width of the window, the depth of the windowsill, the condition of the window frame, whether the unit is installed on the top or at the bottom of the window opening and how much of the air conditioner extends outside the window.

Your co-op / condo board should have established installation guidelines and procedures that residents must follow. For example, you may need to comply with a rule that window air conditioners be installed only by someone deemed "qualified," such as the building superintendent, a maintenance person, a technician from the store where the unit was bought or perhaps an exterior contractor. (Note that are there are no licensing requirements for installers.) You might need to complete a simple form verifying that a qualified installer put in the A/C.

To maintain a uniform standard of safety, your board might well not allow you to install window air conditioners on your own, especially on street-facing facades. While you might feel this isn't necessary when you can do it yourself, you can compare this issue to that of apartment alterations. Most of us accept that we cannot renovate our apartments without board approval, since accidentally removing a load-bearing wall or rupturing a gas or plumbing line, for instance, would damage not only our apartment but possibly others'. Similarly, without established A/C installation guidelines that require a qualified installer, some residents will no doubt hastily shove a unit in a window, close the sash, and be done with it. The more apartments in your building, the greater the risk that someone will not adequately secure his or her air conditioner.

As more and more cooperatives and condominiums adopt rules for window air conditioners, requiring approved installations will gradually become an accepted part of building operations.

Stephen Varone and Peter Varsalona are principals at Rand Engineering & Architecture.

Adapted from Habitat April 2006. For the complete article and more, join our Archive >>