I have high water pressure (120PSI) and I keep hearing what sounds
like a pressure relief valve blowing off momentarilly. Could the 825 be responsible for this? It is rated for 140 PSI could it need a rebuild? Has anyone experienced this before. It just did it again even with the sprinkler on?
The type of backflow preventer you have will do that at high pressure, which is why they are installed outdoors. It is not a malfunction. You can see the discharge after each zone valve shuts off.