• In this video, This Old House plumbing and heating expert Richard Trethewey explains how to install a mini-split air conditioner.


    1. Lay pad on ground, check for level, then set condenser unit on top of pad.
    2. Use 1 ½-inch hole saw to drill hole through house for refrigerant line.
    3. Feed refrigerant line through hole and into basement.
    4. Open up wall in room where air conditioner will be located.
    5. Run refrigerant line from condenser up to room.
    6. Assemble PVC drain line and run it to room.
    7. Pull electrical cable and low-voltage wire from condenser to room.
    8. Screw metal mounting bracket to wall at manufacturer's recommended height.
    9. Hang the air conditioner unit on the bracket.
    10. Make final connections, including refrigerant line, PVC drain and electrical wires.
    11. Install the air conditioner's cover.
    • Difficulty: Moderate to hard
      You can install the ground pad, bore holes and run drain and electrical lines, but leave the final mechanical hookups to the pros

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      Video Directory

      Selected Topic/Section

      Tools List

      • drill
      • drywall saw
        1 ½-inch hole saw
        to make hole for refrigerant lines
      • two-foot level
        used to level pad that supports condenser unit
      • hammer
        Drywall saw or jigsaw
        used to cut hole in interior wall
      • needlenose pliers
      • wire strippers
      • Wire strippers

      Shopping List

      1. Mini-split air conditioner

      2. Ground pad, for supporting condenser unit

      3. 1-inch-diameter PVC pipe and assorted fittings, used as condensate drain line

      4. PVC primer and cement, used to join together PVC drain line 5. Armor-sheathed electrical cable, provides line-voltage power to the air conditioner

      6. Low-voltage wire, sends signal from air conditioner to condenser