What would cause a clicking noise in an ABS ventilation stack after running water in the first floor kitchen or second floor bathroom?

Answer 1

I have this same problem and have not yet contacted a plumber about it but I may. My home is super insulated and uses an number of technologies for heat retention that were more common in Canada in the past. Now building code in the northern U.S. has begun adopting standards such as HRV's (heat recovery ventilators) and perhaps some heat retention Plumbing techniques as well. Here is my guess. More than likely this is a vent stack check valve to slow the penetration of sub-zero air from freezing the water in your P traps. The valve has gotten old and the soft rubber O ring has either fallen off and washed down the sewer or just hardened. As your waste stack drops its load and draws air behind it this check valve opens and closes intermitently and as it slams shut you hear an audible click or tapping noise. This can even happen when the barometric preasure above the stack changes relative to the preasure below the valve. Even wind can cause mine to process once and awhile. If you discover differently please post as I am not ready to pay for the damage it would take to excavate this valve from the wall and replace it. ABS has a very high expansion rate. I bet it happens when you run hot water. The pipe "grows" and ticks as it rubs against wood or sheetrock. Then it ticks slower as it cools.