Q&A: Replacing a through-the-wall air conditioner

Consumer Reports News: July 19, 2010 11:31 AM

I need to buy a new air conditioner, but my unit sits in a sleeve in the wall. Can I buy a regular window unit or does it need to be a special through-the-wall air conditioner?

Unfortunately, it's not as easy as simply sliding a window unit into the old sleeve. Your best bet is to replace the old unit with a new through-the-wall unit.

If, for some reason, you can't find a similar substitute, you should only use a window unit with a removable chassis. Special vents are located on the top, back and sides of an air conditioner housing for intake air as well as exhaust. Placing an air conditioner with a non-removable chassis inside the sleeve could block some of the existing vents on the unit and degrade its performance. The chassis should closely match the width, height, and depth of the existing sleeve and wall. If not, internal components could be covered by the thickness of the exterior wall and impede proper air flow.

If all of the dimensions are close, make sure there is a way to secure the new unit to the existing sleeve. If not inserted properly, it could vibrate and create higher noise levels. Interior trim might be necessary to cover any gaps.

Many models designed for through-the-wall installation come in standardized dimensions. Knowing your exact dimensions and BTU needs will help you find the right model. And don't forget electrical requirements—many larger, older through-the-wall units are 220 volts. If you purchase a new 110V unit make sure you have access to a standard outlet. The big box stores (Home Depot, Lowe's, Walmart) may not carry a large selection of through-the-wall models. You may have to shop at a smaller appliance store or special order the unit. Through-the-wall units also tend to be more expensive.