Wilkins Backflow Preventer Installation

Wrap thread seal tape around the threaded ends of the output line and the intake line. Thread it clockwise so it will not unwind and bunch as you thread on the elbows. Thread elbows of the proper size over the Teflon. Tighten the elbows with a pipe wrench. The elbows' openings must face up.

Screw seal threaded pipes into the elbows. Tighten with a pipe wrench. Use a bubble level to assure the pipes are straight up and down. The length of these pipes is determined by the flood line. The backflow preventer must sit 12 inches above this line. As a result, the vertical pipes must equal the distance from the output and intake lines to the flood line, plus 12 inches.

Wrap the ends of the vertical pipes with thread seal. Add elbows with a pipe wrench, the openings facing one another. Measure the distance between the two elbows and subtract the length of the backflow preventer. Divide that number by two. This is the length of pipe required to run horizontal to the output and intake lines from the elbow to the backflow preventer, one on each side. Thread seal the end of one of these pipes and screw it into the output elbow.

Thread the other end of the horizontal output pipe. Twist the backflow preventer onto the pipe with a wrench. Make certain you thread the intake side of the preventer onto the output line. If your preventer has a drain pipe, seal thread the pipe, slide the output end into the drain and twist the threaded end into the bottom of the preventer. Seal thread and twist the second horizontal pipe into the outflow end of the preventer, then into the intake line's elbow using the wrench.