How to Install a Y Joint Washing Machine Drain

Written by michael logan
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The convenience of having a washing machine in your home can't be beat. Laundry sinks were once the norm for a laundry room with a washer hookup. The provided a place for the dirty water to drain out, and with the addition of hot and cold water taps, all you needed were hose hookups. If you need to add a washing machine drain to an existing drainpipe, the procedure is easy and just requires a little know-how.

Skill level:

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Things you need

  • Tape measure
  • Reciprocating saw or hacksaw
  • 2-inch PVC or ABS pipe
  • 2-by-2-by-2-inch PVC or ABS Y fitting
  • 2-inch PVC or ABS P-trap
  • PVC or ABS glue and primer
  • In-wall plastic drain mount
  • Scrap 2-by-4 blocks
  • Permanent marker
  • Rag
  • Safety glasses

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  1. 1

    Mount the inwall drain adaptor between two studs according to the manufacturer's instructions.

    How to Install a Y Joint Washing Machine Drain
    Basic Y fitting
  2. 2

    Determine where to cut the existing pipe drain by temporarily assembling the P-trap and connecting the tail to the Y fitting. Position the P-trap directly below the opening for the pipe in the drain adaptor, and hold the Y fitting against the existing drainpipe. Use the illustrations for guidance.

    How to Install a Y Joint Washing Machine Drain
    Complete washer drain set-up
  3. 3

    Mark the existing horizontal drainpipe for cutting. Hold the Y fitting against the pipe and mark it so that the cut ends will be inside the hubs of the Y fitting. Cut the pipe with a hacksaw or reciprocating saw.

    How to Install a Y Joint Washing Machine Drain
    Using the fitting to measure for cutting
  4. 4

    Temporarily install the Y fitting onto the pipe. Connect the P-trap tailpiece, and support the P-trap with pieces of scrap lumber. Measure and cut a piece of pipe to fit between the P-trap and the inwall drain adaptor. Temporarily install the pipe and make any adjustments to the fittings.

  5. 5

    Mark the Y fitting orientation on the existing drainpipe and fitting with a permanent marker. Also mark the orientation of the P-trap connections.

  6. 6

    Disassemble the fittings and prime each hub as you go. Also prime all pipe ends. Allow the primer to dry a minute before gluing. Use care not to erase the orientation marks you made.

  7. 7

    Apply glue to the ends of the existing drain pipe first and the corresponding hubs on the Y fitting. Fit the Y fitting onto the pipe ends, rotate to align the orientation marks made in Step 5, and hold the pipe ends tightly in the hubs for 30 to 60 seconds. Use a rag to wipe off any excess glue.

  8. 8

    Apply glue to the end of the P-trap tail piece and the Y fitting hub. Insert the tail piece into the hub, rotate to align the orientation marks, and hold together for 30-60 seconds. Continue assembling the pipes in this fashion until done.

  9. 9

    Support the P-trap from underneath with 2-by-4 blocks or other lumber. You can also use plastic strapping and connect it to the studs. Use several pieces of strapping at different points. Fill the P-trap with water, and test the drain by filling the washer and setting it to the spin cycle.

Tips and warnings

  • If there is no existing drain, you'll have to run pipe over to another drain pipe or soil pipe.
  • The joints of PVC or ABS pipe are actually welds. The primer cleans the pipe and makes it ready for the glue. The glue dissolves some of the plastic on both the pipe and the fitting in one chemical reaction, then hardens into a weld in another chemical reaction.
  • Always use primer, and glue only one joint at a time when possible. It is best to rotate the fittings or pipe 90 degrees or more so the glue gets spread evenly. Always mark your fittings for orientation before gluing so you get the alignment right during gluing.
  • Although 1-1/2 inch pipe will work most of the time, it won't work well all the time. 2-inch pipe works well with the flow from most washers. Always use 2-inch pipe to insure against overflowing the drainpipe and flooding the room.
  • Proper venting means good operation. Improper venting could cause the drain to overflow and flood the room. Be sure the drain is vented within 10 feet of the new P-trap.
  • The glue and solvent should be used with good ventilation. Also, the vapours are flammable, so turn off pilot lights, gas water heaters and gas furnaces in the room where you are working.
  • Check local building codes and obtain permits when required. Building code inspectors are good sources of information and advice; use them.
  • Always wear safety glasses when using any kind of saw.

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