Curious George asks:
Just curious, on a washing maching water hook-up, why is there a tall (~1 ft) pipe going toward the ceiling; it is coming off both of the water lines and has a cap on the end? So, the copper piping bringing in the water comes down in an L shape but right before the knob to turn the water on/off there is a pipe going up toward the ceiling. I don’t see these on the shower lines or any other water line…
Answer by car dude
whoever installed the water lines for the washer hook up was trying to eliminate water hammer. water hammer happens when the water valve in the washing machine shuts off quickly, and causes the pipes to bang throughout the house. those extensions will work as long as they are full of air, if they fill with water, they no longer will do what they were intended to do. you can buy water hammer arrestors that will do the job better, from any place that sells plumbing supplies.