How to Replace Sewer Vent Traps

Measure the diameter of your pipes to determine the size of the replacement trap you will need. Place your pipe wrench over the outside of the pipe and lightly clamp it down. Remove the wrench without loosening the wrench and measure the distance between the jaws to determine the outer diameter of your pipes. Purchase a replacement trap suitable for the outer diameter of your pipes.

Place the jaws of the pipe wrench around the rotating hexagonal nut where the trap connects to the plumbing behind your fixture. Gently tighten the pipe wrench until the jaws do not slip without crushing or deforming the pipe. Rotate the wrench to loosen the nut around the pipe. Hold the pipe in place with your nondominant hand and apply more pressure if the nut does not turn easily.

Repeat this process for the hexagonal nut on the other end of the trap. Loosen both nuts until you can turn them without the wrench before unscrewing them completley. Pull down gently on the vent trap to remove it from the pipes.

Remove any accumulated dirt or debris visible inside the plumbing lines attached to the plumbing trap. Firmly insert the ends of the new plumbing trap into the open pipes in the wall and beneath your plumbing fixture. Press the closest hexagonal nut straight down on to the threads of the plumbing trap and slowly rotate it back and forth until the threads catch. Repeat this process with the other nut.

Tighten the nuts until they become difficult to turn. Place a small trashcan or bucket beneath the plumbing trap and run water through the plumbing fixture to make sure that it is watertight.