Hello. When the sink is used in my upstairs bathroom there is a loud pop, or clicking sound coming from within the wall where the drain pipe is. Strangely, you can’t hear this noise on the 2nd floor, only on the first floor. I thought it was water hammer, but arresters did not help. The more I listen to it though, I am pretty sure it is not water supply lines but indeed the PVC drain pipe. It will make that loud tick (sometimes louder than others) or bang noise every 20 seconds or so for several minutes, but it will keep doing it for about 40 minutes after the sink has been used for a few minutes. What causes that, and what can I do? I thought about insulating the wall, or maybe knocking it open, and putting some sort of sleeve over the pipe so it is cushioned? Any advice? thanks
This is caused by thermal expansion of the pipe. The sound is the movement of piping against wood or whatever it is rubbing against. The only way to cure this is to open the wall and sleeve the opening, or cut out the area larger where it passes through, then sleeve the area.