Back Again with an update (if anyone's interested
Maybe someone will tell me if I'm being dumb anywhere here...
I've been following Wet's recommendation of a long hard look at the system, particularly at balancing flow as the first step of fixing things - lets call this phase 1 of the project
Conclusion is that most of the excessive flow rates are due to inappropriate replacement of heads...
Zone 12: Flow rate is 45gpm. Original heads are Toro 570 with 12' half-circle nozzles - 1.09gpm @30psi, spacing 10ft on a 9ft wide bit of grass. 13 of 28 heads have been replaced with nasty brass popups, flowing >2.5gpm. Math tells me that if I replace the brass popups with the same heads as original, I'll be back at 30gpm. Though I may use rainbird 1803 sams on 3 of them, which are on a narrower strip of grass (6ft) running downhill. These are spaced wider (12') than the heads on the main part. 6ft strip with 12' spacing tells me I should try strip heads.
Zone 9: FLow rate is 56gpm. Entirely due to being afflicted with the nasty brass popups. Easy fix with either 570s or 1803s.
Zone 13: Flow rate 75gpm. Can of worms. Appears to have originally had 22H-SS streamers at top and bottom of steep slope. Half appear to have been replaced with an assortment of home-center impact and gear rotors. So far, I've retired the impacts and renozzled the Orbits and KRains to smallest nozzles - somewhere in the .5 to .75gpm area. Result? Original head pressure was 40psi. After changes, pressure went up to 60psi, flow remained at 75gpm. So I used the valve flow control (which I guess keeps me on-topic for this forum) to bring head pressure back down to 40psi, and that got flow down to 45gpm. A major improvement, but not yet where I need to be. I spy a number of nasty brass shrub heads lurking where 22H-SS used to be, so I'll look at those next. At this point I don't know whether I'll get to 30gpm, or whether I'll need to split the zone.
Well, off I go shopping for 570s. Sprinkler warehouse don't seem to carry the 3" ones
- de