Hot Water Pipes Making Noise

kubichekb

I recently moved into an apartment where one of the hot water pipes is making noise. When I turn on the hot water in the bathroom (and specifically the bathroom), there is a banging noise from behind the wall. The noise seems to hit less frequently in the beginning when the water is turned on, then hit more frequently, and then after a while the frequency slows back down. I have read about water hammer, and I do not believe that is the problem becuase it occurs when the water is running. The thing that puzzles me is that it will "knock" more slowly at first and then speed up. It actually continues to knock after I have turned off the water as well, but it eventually stops. I would really appreciate any suggestions as this noise is sort of driving me nuts. Thanks!

<*(((><

It is most likely that the plumber didn't secure the hot water pipe to the studs in any fashion. You can probably notice the "banging" more if you were to turn on and off the hot water, which changes the pressure in the lines.

troubleseeker

My suspicion is that the water lines were not properly secured, and what you are hearing is the noises as they expand and then contract, rubbing against the studs they pass through. It would make sense that the noise would increase as the temp of the pipe increased with water flow and expanded more rapidly until reaching it's max temp. Then the reverse happens as the pipe cools down and retracts. You are correct in that true water hammer noises are the result of sudden stoppage of water flow in a pipe, generally caused by appliances with valves that shut quickly, such as dishwashers and washing machines, but modern lever handle fixtures can be shut quick enough manually to create this also.
Sorry to say that I don't know of any solution unless you can get to the pipe in the wall.