How to Insulate a Window Air Conditioner

Before installing a window air conditioner on the cusp of those sweltering summer months, the window must be properly insulated, so that the cold air produced by the unit doesn’t escape the room. Escaped air forces the unit to work harder in order to replenish the lost cool air. Some units come with a roll or weather seal or sealant strips. If not, a roll of weather seal can be picked up at a hardware store.

Weather seal
Scissors
Tape measure

Instructions

- 1
  Measure the windowsill and the sash with a tape measure. Cut two strips of weather seal that are the same length as the sash and the sill. Peal the backs off of the strips, and press the adhesive side of sash-length strip against the underside of the sash and the other against the top of the sill.
- 2
  Place the air conditioner unit in the window, and mount it properly to the window frame and outside wall. Pull the accordion panels from the sides of the unit out to the sides of the frame.
- 3
  Measure all sides of the two accordion panels. Cut weather seal strips that are the exact same length as the measured sides. Peal the adhesive backing from the strips, and press the strips to their designated frame sections between the frame and the panels. Screw the panels into the frame to secure them against the insulation.
- 4
  Measure the top of the open window, after the supplied L-brackets are installed there to prevent the window from opening. Cut a strip of the weather seal the same length as the open window top with the scissors. Peal the backing off of the piece, and press it between the open window and the stationary window to staunch the created opening.
- 5
  Inspect the rest of the air conditioner and window frame for openings. Apply weather sealant strips to the found openings.

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