SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I have a sprinkler system that was installed with a neighbor over 15 years ago. I have been bad heads and valves. The main coming in is 3/4" PVC and the neighbor choose to go with 3/4" PVC for the entire system. With that said I will not be redoing the entire system with 1" PVC, but I do want to bring the system up to code and install a PVB.

1. Should I go with a 3/4" PVB since the system is 3/4" or should I go with a 1" PVB and use 3/4" to 1" coupling before entering the PVB and upon existing the PVB use a 1" to 3/4" coupling?

2. What would be the effect of using the 1" PVB with the 3/4" to 1" (vice versa) couplings?

I am also currently experiencing water hammer (with the shockwave going to the weakest "pipe" in the house, the water tube for the fridge) every time the main valve turns on, but there is no water hammer as each zone valve is opened and going through the program cycle.

3. What can be done to address this water hammer issue assuming I do not want to install a pressure reducing device?The zones I would say were designed a bit poorly and some have too many heads leading to some under coverage. I know that using such device would only reduce the pressure to the heads so using a pressure reducing device is not a possible solution.

Thanks