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

Hi all,
I've got a bore in my backyard. The bore is powered by a 440V three phase motor driven pump.





I don't know much about pumps, so I can't say what kind of pump it is. I've got a simple switch in the house to switch the pump on and off.

Pump Switch (opened up)


The zoning is simple: one zone for the front, the other zone for the back of the house. To switch between the zones I used manual 50mm ball valves.



The system worked fine for the 2 years I've lived in the house, and probably for many years before that.
Now I've decided to automate the system. I started by buying 2x 50mm solenoids. I cut the old valves out and replaced them with the new solenoids. I've also added a pressure relief valve to protect my pump.

The old and the new valves


New valves installed


The next day, when the PVC glue was dry, I went to test my new system. The controller isn't installed yet, so I used the manual switches to turn the solenoid for the front garden on and the back yard off. Because I didn't want to get wet, I've put the pressure relief valve to a very high threshold (200 psi), with the plan to open it slowly when the pump is running to see at which pressure level it starts opening.

When I started the pump, my pipes started shaking. Then I could hear water going through to the front yard. The sprinkler heads popped up - everything seemed fine.

After about 10 or 20 seconds, I could hear a rattling noise in the pipes. Then the water stopped. I could still hear the motor running, but there was no water coming out the sprinklers.

I switched off the pump and started trying all sorts of diffent valve combinations, repeatedly switching the pump on and off - with very strange results. In one of the tries, I changed from front to back yard and put the relief valve to a very low setting (50 psi). Then I switched the pump back on. Everything went ok. Backyard sprinklers working fine.

I played a bit with the flow control, to see how that effects my sprinklers. When I had the flow control almost closed, the sprinklers shut off and the relief valve opened - as planned.
With the pump still running I opened up the flow control again, but the sprinklers wouldn't come back. So I switched off the pump, waited for a few seconds and switched it back on.

What happened now I can't explain, yet I could reproduce the problem a few times. When I switched the pump on, my front yard sprinklers started up - even though that valve was closed! My backyard stayed off, even though the valve was open. Again, after a few seconds the pipes started rattling and the front yard sprinklers would turn off again, leaving only the relief valve running.

I could repeat this several times. I even asked my wife to come and check my valve settings, because I stopped trusting my senses.

I'm completely puzzled. Does anyone have any ideas what could be wrong?

Thanks
Chno

I have done that, too. I've removed the relief valve entirely and left the pipe open. Then I closed both solenoids. The water came out of the pipe that led to the relief valve - so the pump seems to be working fine.

Just to close this off: the mystery is solved.
As long as the solenoids weren't connected to the control system, the manual opening of the valves didn't work properly. They shut off by themselves after a few seconds. I don't really know why, but that's what happened. To make sure the valves stay open I had to open the bleed screw - that worked fine. Once I had the control system connected, the current kept the valves open. Now the system works perfectly.