Install an Inwall Air Conditioner
Central air conditioning (AC) is a wonderful thing—except when it isn't practical. You may have a second building that needs AC, or a refurbished garage or attic that swelters in the summer. You can use the windows, but those are bulky, noisy, and cut out 50% of the window light. The solution? An in-wall air conditioner! They're quiet, efficient, and will keep you cool!
Steps
- Pick a location where the AC will be installed. Try not to locate above electrics and electronics because they may be damaged by condensation from the discharge air grates on very humid days.
- Plan to keep the bottom of the unit 1 to 5 feet (30 to 150 cm) from the floor to minimize dust from the floor clogging the filter, and condensation forming on the ceiling.
- Locate the wall studs. Use a stud finder, visually inspect baseboards for nail heads, or rap on the walls with your knuckles—you can hear the sound change from hollow to solid as you rap over a stud. (Commonly, studs are 16 inches apart in the U.S.)
- Lightly indicate with pencil on the wall where these studs lie.
- Roughly indicate the layout of the AC unit on the wall, in such a way that the number of studs to be removed are minimized.
- Clear the area. Remove any molding above and below the intended opening location.
- Remove the drywall between those studs indicated from the floor to the ceiling first by scoring the wall with a razor blade (utility knife) along the inside of the studs.
- With a hammer or gloved fist, knock out just enough drywall to locate any wires or other obstructions that could be damaged with a saw.
- Use of a utility knife works surprisingly well on drywall, and will result in the least amount of dust and risk of damaging wires and pipes in the wall space. To use the knife, repeatedly score the wall top to bottom. You do not need to completely penetrate through the drywall—just get through 1/2 to 3/4 of the thickness. A sharp hit on the wall with a gloved fist will break the drywall along the scored line.
- Alternately, you can saw out the drywall by cutting as close as possible to the side of the studs. Use of hand saws made for drywall will minimize dust. If using a Sawzall or similar, a helper with a vacuum following your cutting path will reduce dust considerably.
- Remove the insulation.
- Remove the center stud(s) if needed to accommodate the AC unit.
- Transfer the dimensions of the AC unit or sleeve to the inside of the outside wall.
- Set the placement of the exhaust opening so that the top will fall just under the edge of a full clapboard, shingle, or other siding section—wherever it will be most aesthetically pleasing (or rather, least aesthetically displeasing).
- Create the hole for the outside of the unit. Mark the outside opening using a template if provided by the AC manufacturer, or draw one in.
- If you draw your own template, use a framing square and level to ensure that your opening is level and square.
- Add 1/4 inch to the height of the opening. This additional 1/4 inch will allow the unit to be angled slightly downward on the outside to prevent condensation and rainwater from collecting in the unit and leaking inside the house. If you have a specific point for the top of the opening, add this 1/4 inch to the bottom for the new line to cut.
- Carefully create the opening by cutting along the lines with a Sawzall.
- Build supports. Cut a stud to fit against the two studs that make the sides of the opening created for the AC unit.
- Level and install at the bottom edge of the AC unit location.
- Cut a board to fit between the wall stud on the floor in the wall space and the bottom AC support installed in the previous step.
- Screw or nail these studs to the existing studs. There should be three (possibly four if the unit is very large) new vertical studs in the space below the unit; all of which run from the bottom to the underside of the horizontal support; one in the middle, one against the existing left stud and one against the existing right stud.
- Fabricate a header. It will be the top of the framework for the opening.
- Cut two (2 x 4 construction) or three (2 x 6 construction) pieces of the same length from a 2-by. Cut one or two (again, 1 for 2x4 or 2 for 2x6 construction) strips of 1/2" plywood the same size as the 2-bys.
- Place the plywood strips between the 2-bys and nail or screw together. The completed header thickness should be very close to 3-1/2 or 5-1/2 inches (for 2x4 or 2x6 construction, respectively).
- Cut two 2-bys equal to the opening height. Secure them against the existing studs in the space for the unit, by resting on the bottom horizontal support previously installed and nail or screw in place.
- Rest the header on top of the vertical supports installed in the previous step.
- Secure the header by nailing or screwing in place.
- Add studs. Cut a 2-by to fit between the header and the top plate (the 2-by that the left- and right-most studs are secured to at the top) plus 1/8 inch at the left-most stud and nail or screw into place.
- Hammer these studs into position.
- Repeat for the right-most stud and for at least as many vertical studs installed in previous steps below the unit, in the space above the new header. If one stud was cut and installed in the middle of the wall space for the bottom support of the unit, then at least one (but more would be better) will be required above the opening as well. These studs above the header should fit tightly. If not a tight fit, cracks may develop on the wall surface as the weight settles on the new framework in the wall.
- Finish the frame. Cut two 2-bys equal to the height of the opening. Making this cut a little long (1/16 inch or so) will help ensure settling will not reduce the opening and minimize any movement. Hammer these 2-bys along the left and right side of the opening. Nail or screw in place.
- Install any electrical outlets required while the wall is open.
- If the unit is high on the wall, consider installing an appropriately rated switch at this time for the outlet, as this will make powering the unit on and off easier. It will also reduce the chance of damage during electrical storms if set to off.
- Put the wall back where you found it.
- Reinstall the insulation.
- Install the drywall.
- Tape, mud (joint compound) and sand when dry.
- Paint wall and reinstall all molding.
- Install the AC unit. Remove unit front cover and screws that hold the unit inside its case.
- Pull the unit forward while an assistant holds the case, until it is fully withdrawn.
- Install the case or sleeve into the opening. Allow several inches of the case or sleeve to protrude from the wall into the room.
- Measure the amount of protrusion at one of the top corners, and start a screw through the sleeve or case close to this corner into the framework to keep it from moving.
- Move the case or sleeve in or out so that the other top corner has the same amount of protrusion. Start a screw through the sleeve or case close to this corner into the framework to keep it from moving.
- Repeat this procedure for the bottom corners, but remember to have the protrusion here 1/4 to 1/2 inch greater than measured at the top. This creates a position for the case or sleeve that is tipped downward to the outside and will minimize the chance for condensation and rainwater from collecting and leaking inside.
- Once the case or sleeve has been tacked into position, firmly secure it by driving at least two screws into each of the four sides.
- Caulk around the unit.
- Caulk around the inside and outside of the unit by running a generous bead between the unit and the surrounding surface. Extra time spent here will ensure a seal that will help keep water out. Do not scrimp—use a high quality 30-year (or more) caulk rated for use outdoors. Make sure it is paintable.
- Install molding. Add trim around the unit inside by cutting appropriate length boards at a 45-degree. Secure with finish nails. Set and fill nail heads and paint.
Tips
- See other Wikis about installing outlets and switches for the electrical portion of your installation.
Warnings
- An air conditioner sleeve is required for windows type units that do not allow for the removal of the air conditioner from its case. Without the sleeve, there is no way to secure the unit into the opening. When using a sleeve, references to cutting an opening to match the dimensions of AC, unit, etc. should be interpreted to the sleeve instead of the unit case.
- Sleeves are also nice to have so that if the unit should ever need to be replaced, finding one the exact same dimensions won't be required. Simply pull out the old and slip in the new.
- Sleeves will need additional time and material to custom fit the unit into the sleeve. That part is up to you complete for your particular application. It should at the very least include insulation and trim boards. After stuffing insulation around the top and side(s) of the unit, secure trim boards with screws through holes drilled into the part of the sleeve that extends into the room. Be sure not to cover vents (if any) on the sides of the unit.
Things You'll Need
- Lumber (2x4 or 2x6) to match the construction of your home.
- Drill
- Philips bit and magnetic holder
- Sawzall
- Utility knife and blades
- 2-1/2 inch nails or screws
- Molding for inside trimming of the opening
- Finish nails
- Nail set
- Drywall
- Joint compound
- Drywall tape
- Putty knife
- Caulk
- Caulking gun
- Insulation or low expanding foam insulation for sealing cracks and voids
- Miter box for cutting 45-degree angle molding
