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Starting Member

Posts: 1

Location: Raleigh


Tuesday, August 10th 2010, 7:01am

Pump cycles on and off.

I've got a Rainbird system and recently noticed the pump cycling on and off during the time outside my normal watering schedule. I've checked the system pressure and noted the pump cycles on when the pressure drops (the way it's supposed to do when the system is in operation as commanded by the controller). This is occurring while the system is on, but not in operation. I'm wondering if one or more of the zone valves might be stuck in the open position and thus causing a drop in system pressure and the resultant cycling. Also, how much air pressure do I want in my tank?

This post has been edited 1 times, last edit by "dfcooper" (Aug 10th 2010, 7:07am)


Supreme Member

Posts: 482

Location: Houston, Texas


Tuesday, August 10th 2010, 11:45am

That could be it.

You may also have a leak in the mainline that would cause low pressure.

Air pressure in the tank depends on your system design what kind of heads rotors or spray? What brand and nozzle?

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Central Irrigation

Supreme Member

Posts: 371

Location: Central Minnesota


Tuesday, August 10th 2010, 7:06pm

Could be a handful of things. Like hi Todd stated, if there is any leak in your mainline, the pressure in your pressure tank will drop causing your pump to kick on. The easiest way to check your mainline is to pressure test just your mainline. You'll need to find the shut-off valve that will isolate your system from the rest of the house and close it. The proper way to pressure test a main would be to use a pressure gauge inserted into one of the fittings on your backflow preventer, but there is a simpler way. Close the shut off valve and leave it closed for 5 minutes. Open the valve slowly and listen for the sound of water flowing through the partially open valve. If your hear any water flow, you have a leak in your main. It's not a perfect method, but will get you started.

Check your zone valves also. A weeping valve (a valve that doesn't seal completely) is also considered a leak in your mainline. Typically, a weepy valve is found by water constantly draining out of the lowest head.

I believe the tank air pressure should be within 5psi below the pump cut-in pressure. If I'm wrong, someone will chime in.

Keep in mind, a properly designed well irrigation system will not let the pump turn off.

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