On Feb 12, 9:04*pm, "Chas" wrote:
Before I caught my hot water tank venting during the water hammer I had
inserted two 4 foot 1/2" copper capped tubes vertically inside the wall
above my washer water shut off valve, trying to make a resevour to capture
air to dampen the hammer. *That didn't work. *Later in my basement I silver
soldered some refrig valves (Schraeder) into the hot and cold lines under my
laundry room. *I have an air compressor in my basement and a 'main' with
many quick connects. *One was handy to this area and I injected air into the
laundry water feed lines, but didn't get much result. *This was a waste of
time and money. *The regulator was the trick.

A proper water hammer arrestor is the solution.
Either piston or bellows style.

http://www.watts.com/pages/_products...ls.asp?pid=741
http://www.watts.com/pages/_products...s.asp?pid=7137

cheers
Bob