Ok... I have a sprinkler system at my house, which up until 3 weeks or so ago had worked fine. Now, when we run the sprinkler system, there is a "banging" noise coming from the pipes, and more specifically my hot water tank in the garage. The strange thing about it, is that we have 7 zones in the system (3 in front, 4 in the back) and the banging noise only happens when one of them is running. When this one zone is running, the water pulsates in the sprinklers, as well as in the house (shower, faucets, spickets outside... etc). Once this section of sprinklers is done, it goes back to normal and finishes with no problem. I noticed at the top of the water heater, that one of the pipes/tubes leading into it from the actuall copper piping seems to be moving or shaking with the banging/pulsating. Any suggestions or thoughts?

Thanks, Mike!