I had to replace the shut off valve for the supply to the dishwasher. It was dripping under the sink. Aggravating, it probably hadn't been turned but a couple times it's whole life. Anyway, I shut off the water from the main supply in the basement, drained the system from a nearby hose bib and put on a new quarter turn shut off for the DW. I did not change the supply line which is copper tubing. Ever since, there is a very annoying water hammer all over the house. When any toilet float closes, washing machine stops filling, or if you normally close any faucet (if you close it extremely gently no hammer). The whole system is 1/2" copper, and all terminations have the 6 or 8" stub for air, which by searching on here it seems most think are ineffective. If anything, shouldn't draining and refilling the system have recharged the air chambers??? I tried re-draining and re-filling a couple more times both with or without opening upstairs faucets, but not much difference in the hammering.
What gives? How could that one change suddenly cause this? The house was built in the 80's. Searching I noted that I should check my water pressure. It's marginally high-75psi, but I don't think that is the problem because it's always seemed the same. I have lived here 3 years with never a hammer until now.
Any suggestions greatly appreciated.