Pressure vacuum breaker making noise when auto-fill comes on
We have a new pool. The plumber originally installed an A&A Quik Water Leveler (http://aamfg.com/waterLeveler.php). I guess some rocks got into it so my pool guy replaced it with a home depot standard toilet filler. Pretty normal I guess... The only problem is that when it is filling, it kind of does it in spurts which is normal as I guess due to waves in the pool. These spurts cause the wilkins valve at the water source to make a noise that lasts about a second. It's kind of annoying in the house because you can hear it. Is there anything I can do to fix this? Replace the auto-fill or the wilkins? There is a valve on the water source side of the vacuum and one on the output of the vacuum. Someone suggested adjusting one or both of the valves by turning them to about 50% but that didn't seem to help. The person called it water hammer although the noise is not so much banging but just kind of a loud flow noise?
You need to ask yourself, Is it worth the hassle and expense of having an automatic pool filler or is a manual fill system acceptable?
If the noise is happening when the flow valve is closing, you have a classic water hammer problem. Given that your use case is a very low flow rate, a pressure reducing valve ahead of the pressure vaccum break or replacing the PVB with an RPZ type of backup preventer assuming that is allowed by your local code combined with a well pack like pressure tank after the backup preventer are the kind of things needed to get rid of the water hammer. That is a lot of expense so you really need to figure out if it that is what is causing the noise. Experiment with holding down the float and quickly shutting it off and try and figure out the conditions that cause the noise.
The Wilkins 720A PVB is going to chatter for very low flow rates when water is flowing. There won't be enough flow to fully unseat the check valve so it is going to oscillate. The Wilkins 720A 1/2 through 1" models use the same check valve which is designed for higher flow rate applications. Finding an RPZ designed for this low of a flow rate to not chatter maybe a challenge as well.