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sprinkler backflow(?) banging

Author: puckhead95 (CA)

To cut to the chase, I think the answer is, "You need a backflow preventer, numbnuts!"

But maybe someone knows otherwise....

I do not have a backflow preventer currently in place between my main and the sprinkler manifold.

I have two symptoms:

1) When the first sprinkler zone turns on, the flow thru the pipes is obnoxiously loud under the house. When zone 2 pops on, the noise dissipates to what I would expect to be normal when the sprinklers are running.

2) Occasionally, my last zone will not shutoff properly. The controller signals the valve to close but the valve sometimes cycles every couple of seconds between off and on until I intervene manually or just shut the main valve off.

So... backflow preventer? Or something else??

Thanks for the help!!!

Robert

Re: sprinkler backflow(?) banging
Author: dlh (TX) you should definately have a backflow device but that is not the problem - - - - - - - PLUMBERS "Protecting The Health Of The Nation"

Re: sprinkler backflow(?) banging
Author: hj You MUST install a PROPER backflow preventer, not the $19.95 one at Home Depot. Problem #1 is probably due to excessive heads on the zone. #2 means you have to rebuild or replace the valve or its mechanism, but it could also have too many heads on the zone, thus not creating enough back pressure at the valve to help it close.

Re: sprinkler backflow(?) banging

Author: NICK (CA)

Sounds like both problems could be at the valves. On the first station be sure the manual flow setting is all the way open on the valve. Restricted water flow can cause the noise you are describing. There usually is a cross knob or a stem coming off the valve. If the pipes run under your house and it is banging it could just need strapping at he one stations piping.

On the second one you need to change the valve, unless it is a good brass valve, then get parts. It doesnt sound like a solenoid problem, but a diaphragm issue unless you have loose wiring. Sometimes you can turn the manual flow control all the way off and on a few times and it may resolve this issue for awhile.

Edited 2 times.

Re: sprinkler backflow(?) banging
Author: LemonPlumber (FL) You might need to understand both the flow rates at operation and the controlling valves to understand.Let me know when you have the numbers.A simple tank check hold at the sprinkler connection would yield great solutions.but may be over kill.