No new plumbing has been done in the house and the pressure is the same it it has always been in other parts of the house. The backflow is an atmospheric. How would I check to see if it is open all the way?
I have about a 20 year old rainbird system with six zones, city water fed and 3-4 heads per zone. Every year I have it blown out for winter. This year I am not getting much pressure (heads won't cycle and flow is weak) on any of the zones. Some heads won't even squirt. I replaced the insides of the flowback valve this year because it was leaking last year, but that is the only thing that has changed (and the replacement parts look exactly like the old ones and are same manufacturer (febco). The ...