We have just purchased a new home (2 months old)and have noticed that after running then shutting off the hot water in our master bedroom ensuite sink(also sometimes shortly after having turned on the hot water) that a banging sound is heard. This banging occurs about every 30 seconds until it gradualy subsides, sometimes taking between 30 minutes to an hour. Also, just recently our dishwasher makes the same noise after having completed the wash cycle. Do you have any suggestions as to what might be causing this annoying sound and more importantly, how it might be eliminated? Condition seems to be linked primarily to hot water use.
Ticking or banging often occurs as the plastic vent pipe expands upward after being heated by hot water and water vapor flowing through the bottom toward the sewer. The warmed pipe then cools. The plastic pipe expands, but is held by friction at several points that pass through the wood framing. When the expansion pressure overcomes the friction of the surrounding wood or clamp, the pipe quickly moves until held by friction again. This can happen strongly enough to be a bang, or weakly enough to sound like ticking.