When the hot pipe is connected to the cold side of a sink or shower and the cold pipe is connected to the hot side, making it so when you turn the hot knob you get cold water and when you turn the cold knob you get hot water.
I had the hot water knob on for five minutes and it still didn't warm up. It was then that I realized that the sink had reverse plumbing.
by chonk cat December 13, 2011