How come when a customer has had a system working fine for yr. If the pressure tank on the houses boiler is replaced it always seems to create water hammer when the system starts. I had 1 call like this last week and another for this tuesday . Last 1 I changed the wires so drip would come on first instead of last reducing water demand and speed. Next weeks dosnt have any drip and I may need to nozzle down the #1 zone.