The system is hammering because the various valves are slamming shut
and causing a shock wave to go through the system. Very simple to fix!
Have him pick up a small 2-5 gal. rubber lined pressure tank from a
well supplier. Connect it somewhere near the junction with the yard
piping. The simpler fix is to put a blind riser on the system, but they
tend to waterlog quickly and resume the hammering.
Bugs