Recently I noticed the house water pressure was higher then usual. I checked and it was 85 psi instead of the usual 50-60. I called a plumber to replace the 20 year old pressure regulator, the pressure now looked good but and then the banging started. This never happened in the previous 20 years. Sometimes when running the washer, and it starts to fill the pipes will start a rapid banging. The plumber came back out and replaced the shut off valves at the washer and added water hammer arresters as well. This did not solve the problem and it does it as well when turning on the water in a bathroom tub. Various web sites speculate this could be air bubbles in the system so we tried opening all the faucets in hopes the air bubbles would flow out of the system. It was looking good in that we did three loads of laundry without a problem. Unfortunately it still happens in the tub, and most likely the washer next time it is used. The tub has a single handle faucet that you pull out to start the flow. Pulling it out fast seems to be what causes the problem.

Why would changing the pressure regulator cause new problems with two locations. These appear to be the locations that turn on the fastest so that could be a clue. Even though it is a new pressure regulator could this banging be a caused by fluctuations is the pressure regulator? Could it be bad right out of the box?

Many thanks

Of course any quick closing valves will cause water hammer, especially at that pressure! What may have happened was when the regulator was replaced, he did get air in the line and it made the water hammer that much worse in those locations. Did he open the faucets etc. to bleed the system afterwards?

Back in the 60's we were required to to put shock absorbers,(air chambers) on all bath lavatorys and kitchen sinks. Over time water and condensate built up in them and they must be recharged. First turn off the house at the main house shut off valve. Then open hot and cold faucets at the farthest bathroom to prevent air lock.(This is important.) You will find under each fixture little brass or chrome valves. These are called angle stops. With a small pail held under the angle stop to catch the run off look under the handle of the stop and you will see a nut with the stem running through it. This is called the bonnet packing nut. Put your wrench on it and back it off counterclockwise. Now open the stop and remove the stem and washer assembly, The stop will begain to drain. When it has quit draining reassemble the stop and move on to the next one. Do this on each one of your angle stops. There will be six of them in a two bath home. When you are done, close off the faucets you have opened, turn on the water to the house, and give yourself a pat on the back.
You have just recharged your air chambers and saved yourself a hefty service call bill. Hope this helps you out TOM

Don't know if the plumber bled the system after changing the regulator but we have tried that a few times. Are air bubbles really that hard to get rid of?

Thanks for the reddy The air chambers are hidden inside the wall. If your house is under 45 years old then you already have them. It's not nice to dump on someone who's trying to help.

Sorry I did not mean to dump on anyone. I was unaware of what is lurking behind the walls of our 64 era house. What's a reddy? Can I unreddy?