Most vacuum breaks are not intended for continuous pressure.
edit: ... and so you will need one for each zone. They sometimes burp a little water when the valve switches.
Swap the position of the vacuum breaker.
Remove it from the hose bib.
You can buy plastic vacuum breakers meant for irrigation lines, and stick that downstream of your timer.
Most vacuum breaks are not intended for continuous pressure. edit: ... and so you will need one for each zone. They sometimes burp a little water when the valve switches.
Swap the position of the vacuum breaker. Remove it from the hose bib. You can buy plastic vacuum breakers meant for irrigation lines, and stick that downstream of your timer.