SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Need RPZ if you are going to inject chemicals into the system.

What size line feeds your pvb? 100psi static pressure would never allow a pvb to break it's seal so long as it's supplied with the proper amt. of water!
You have PLENTY of static pressure. Proper operating pressures vary from 35-75psi.
FYI....you're working your pressure losses backwards. Always start where the water starts and follow it through.
Bottom line is, your system is demanding more water than your house can supply, that's why your pvb breaks it's seal.

The main line water pressure is 100, which I believe is roughly reduced by 15 by each sprinkler head (reduced by 60 by the 4 sprinklers in zone 2 and reduced by 45 by the 3 sprinklers in zone 1). I have a 15psi regulator on each of the two drip lines in zone 3, but have not confirmed the pressure. I have noticed a small leak in the polytube roughly 10 feet from the PVB and the first valve tee which obviously would cause a pressure issue. Perhaps when I fix this, the water pressure issue will be resolved but I believe the water pressure issue has existed prior to this leak.

What is the proper operating pressure? The PVB is rated up to 150 I believe. If one doesn't have adequate pressure, what are the alternatives?

My concern is that an RPZ will rob even more pressure from your system. RPZ's, on average, have double the pressure loss of a PVB. If your system pressure is already that low, an RPZ could be too much pressure loss.

I have actually disassembled the PVB unit
previously, but this did not fix the problem.
I believe it is a pressure problem as the issue only occurs when I start the 4 sprinkler zone. Would a reduced pressure assembly have any impact
on this issue or would a pressure issue remain? Last year I had some success with closing one of the valves on the PVB to at least decrease the potential water leaking from the top, but still it wasn't 100% reliable. Unfortunately, I have not been able to replicate it this year. With the installation of the fertilizer injector, it seems that a RPZ is needed anyway.

For small money, just make the current system functional. Do not put a master valve upstream of the PVB. Downstream of a PVB, a master valve with its flow control throttled down can be a cure for the water coming from the PVB, because it better maintains upstream pressure.

Thanks for the feedback. I think I am going to explore the master valve & flow control set-up. I have actually take water pressure reading for each zone, but cannot recall what the pressure is when each zone runs. The 4 sprinkler uses more pressure than the other two so I might remove one of the sprinkler heads in the back (reducing 4 to 3) as well.

Rain bird brass valve $78.09
Hunter-Sprinker-Flow-Clik-Sensor-Tee $172.44
I have not decided which controller to get yet.


Upon further research, it appears my PVB probably won't meet the backflow requirements when using a fertilizer injector. It looks like I need to get a Reduced Pressure Zone Assembly. Not sure how difficult these are to install. I might open a new thread to discuss this. I have seen other posts regarding installation, but could use some additional feedback as well.

I saw this 'plumbing circuit breaker' http://www.flologic.com/flologic-guide/FloLogic-3.0-Feature-Specification.pdf used on This Old House, but I don't want to spend $1500 on such a system at the moment.

Avoid having electric valves upstream of a PVB. Some makes and models do not endure repeated pressurization.

Get a pressure gauge, and read system pressures when a zone opens.

You could also put check valves in your sprinkler heads or try reducing nozzle size.

Generally, a master valve and a flow sensor can be set before a PVB. No reason not to, barring physical restrictions.
You don't need a particular controller. You can use something like the Hunter Flow Sensor with pretty much any 24vac controller.
It sounds a bit like a pressure issue or it could be a failing PVC.
My first step would be to rebuild the PVC. It's very simple and kits are cheap. Our Watts page is HERE.