Pipes bang hard when cold water on full blast
This did not happen prior to our bathroom remodel. Only after our bathroom was redone did the pipes start banging when the cold was on full blast, but this only happened at the kitchen sink. The banging did not happen when you turned the water off. It was when the cold water at the kitchen sink was on full blast that it happened. The remodeled bathroom is on the second floor, not above the kitchen, and if you turned the cold on full blast at the kitchen sink, the pipes in the kitchen started banging really badly.
So we got in touch with the contractor who redid the bathroom, and his plumber did not know why the banging was happening. He tried to remove air from the pipes but that did not solve the problem. Next he installed a vertical piece of pipe in the upstairs bathroom under the sink (picture one attached) but this also did not solve the problem. Now tonight he installed a different type of vertical piece of pipe in the kitchen under the sink (picture two) and this seems to have stopped the horrendous banging.
It seems that these vertical pipe pieces (on the cold lines only) are a patch to the problem, which was not a problem before the bathroom remodel. Our plumber seems to want to blame our new Jado valve, saying that it causes too much pressure in the lines. We want to know why this banging happened in the first place (only the cold full blast in the kitchen) and whether these vertical pipe pieces make any sense. We do not want to have to drain the lines periodically so this alleged patch job continues to work.
PSI is 65. Thoughts please? Thanks in advance.