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

It takes water pressure to create the seal on the pvb.. Zone 3 didn't have much water in the zone intially so when the valve opened up, the demand was so great at first that the pvb lost it's seal. After the zone pressurizes the pvb will re-seal..

The valve is doing it's job.

I don't want to be a buzz kill! If you went from a PVB to a Double Check, You went from a high hazard backflow prevention device to a low hazard backflow device.

It may not be the backflow preventor at all that is your problem.

It could be bad valves or diaphragms that are preventing the valve from opening all the way. Most likely if the problem occurs on the same 1 or 2 valves. You have to ask yourself why do the other valves work.

Back to the Buzz kill. Double check valves are not recognized by many cities and water purveyor as an approved Backflow preventor because they are low hazard.

Check with your local codes, call the permit office or ask a sprinkler company.

Also as a side note.
Toro is not known for being a major player in the world of backflow. You may want to try a febco, watts, wilkins, conbraco made in the U.S.A.

You may need to get the backflow tested upon installation and annually there after. If you install a double check and It is not an approved backflow device, you may not get hit with the pain now, but when you ever try to sell your house it will not be up to code. Most inspectors will get this.

Quoted from "hi.todd"

Back to the Buzz kill. Double check valves are not recognized by many cities and water purveyor as an approved Backflow preventor because they are low hazard.

Todd,
I want to re-inform you some.

In manyarea's, Double Checks are allowed as a proper back flow device for an irrigation system, because in many area's, Irrigation is considered Low hazard .. In Fact.. In ALL regions in the country in the department of health codes, NO WHERE does it say irrigation is rated for high hazard ONLY. There are a couple that do say, irrigation SHOULD BE high hazard and double checks SHOULD not be used because they are rated for low hazard. This is not saying you can't use them though

However this up to your local water purveyor on what they choose to enforce.. So if they say RP's are the only way to go then so be it. IF they allow double checks as a proper back flow device for irrigation, then they can use them.

Yes call your water district up and ask what proper back flow devices can be installed.

Todd, Give me one example/ good reason of why irrigation should be considered a high risk application of cross connection. Just about any cross connection from a sprinkler system would be so diluted by the time it came back from the source

Try to maintain some consistency on backflow advice. If someone does not give out their location. I believe it is not my part to assume they are in a location that allows anything other than toxic-rated backflow devices for irrigation. On this basis, the OP is mistaken when he goes out and buys a DCVA. His present task is to see that the zone valves are in good working order. There is no question but that completely empty zone pipes increases chances of low zone pressures at opening.

Where do you live?

Auto-drains are a horrible water waster.. That is most likely the reason why the PVB was leaking for a bit before it pressurized..

If your in a cold climate area, take those auto drains out and have your system winterized during the winter months