2019 Reflection 337RLS. Last couple of weeks hearing a clunking noise - clunk clunk - when I turn on water - either hot or cold, or toilet. I am full timing in the same place for the last few months and on city water. Sound coming from behind the hutch where the hot water tank and water panel is. Doesn't happen every time, only happens a few times per day. Sounds like water hammer from taking in air somewhere, but I don't know where that would be from. Any ideas ??