APPLIANCES : Wall-Unit Air Conditioning Is So Easy, It’s Cool

If you are among those people who find that a window-mounted air conditioner fills your cooling needs, you should consider installing a through-the-wall air conditioner.

These appliances provide the same amount of cooling as a window-mounted appliance without taking up valuable window space, and they are not difficult to install.

Don’t install a window-mounted air conditioner through the wall, though. There will not be enough airflow around the appliance, and you could have problems with condensation leaking from it into the wall cavity.

A through-the-wall air conditioner has a sleeve that supports it and ensures sufficient airflow. The sleeve also directs condensation outside.

Install the air conditioner on a wall that allows the cooled air to flow freely into the house. It’s best to install the air conditioner on a wall that already has electrical service. However, major rewiring may be needed if the circuit is already crowded or if your appliance requires 220 volts.

Unless you are going to plug the air conditioner into a nearby wall outlet, hire an electrician to do the wiring. This is especially important when the air conditioner needs 220 volts, or when the service panel is old and crowded.

* Start with drawing the outline of the air conditioner opening on the wall using a level.

* Locate a stud on each side of the opening, and draw a plumb line in the center of it, to the floor.

* Remove the drywall by cutting along the lines with a utility knife.

* You will need to build a rough frame to support your air conditioner. It consists of two vertical studs, a horizontal piece at the bottom of the frame called the sill, a horizontal piece at the top of the frame called the header, and short pieces of studs above and below the opening called cripples.

The rough frame is slightly larger than the sleeve that supports the air conditioner by about an inch in width and height. This space allows for shims to be slid between the sleeve and the frame.

* Slide the sleeve into the opening and shim it so it tips forward about an inch from level to drain condensation. On the inside, the sleeve projects about 3/4-inch beyond the frame (check your installation manual for specific clearances). This positions the sleeve’s edge 3/8-inch beyond the drywall.

* Cut a piece of aluminum flashing slightly longer than the width of the sleeve. Bend it at its center, along its length, so it forms a right angle. Use this piece as flashing at the top of the sleeve. Slide one side of the flashing under the siding to seal the joint where it meets the sleeve.

* Once the sleeve is fastened to the frame, move to the outside of the house. Drill through the flashing and into the top of the sleeve and spread a bead of exterior caulk under the flashing. Rivet the flashing to the top of the sleeve with 3/16-inch rivets. Smooth the caulk that squirts from under the flashing and spread another bead of caulk between the flashing and the siding. Caulk the top of each rivet head.

* Return to the inside of the house and pack insulation loosely between the sleeve and the frame.

* Cut a piece of drywall to fit around the sleeve, and nail it in place. Spackle and tape the drywall.

* Fit the cover over the sleeve before measuring for the trim that surrounds it. Miter the trim to fit around the air conditioner cover. There should be a slight gap between the trim and the cover to allow the cover to be slid on and off the sleeve.