Could it possibly be in the device under the kitchen sink. I've installed many of these and never had pipes hammering
either. Call watts and see if they'll send you a new one. Especially if you done nothing different to cause this all of a sudden
We always drilled numerous holes so the water under the floor cold seep in. Try to put small gravel around the
pit to keep the holes from plugging up with mud.
I had about a 6" crack on a verticle 3" pipe and used this compression tape for the first time and was suprised
how well it sealed up. I wanted to replace the pipe but they wanted this fix instead.
You'll need a female adaptor for the AAV to screw into on top of your tee. Take the AAV up as high as possible so if
you need to change it out you can get it out.