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Pressure switch and pump pulseon/off rapidly

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rboscow

New Member

Posts: 2

1

Monday, May 20th 2013, 11:12pm

Pressure switch and pump pulseon/off rapidly

System is 11 yrs old, never a problem. Seasonal irrigation from a ditch. Ran fine for first day of season then started rapid pulse; pressure switch is clicking, pump is going on/off, then pump got too hot and turned off by itself. Replaced pressure switch, no change. Though pump bearings going out, replaced whole thing, Myers 1.5HP QP, SAME DEAL. All zones cycle through fine on gravity. I don't know what else to replace, or what's out of whack.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

2

Tuesday, May 21st 2013, 7:15am

Is there a pressure tank in the setup?

rboscow

New Member

Posts: 2

3

Tuesday, May 21st 2013, 9:36am

No pressure tank. Intake is from buried lateral. Gravity provides about 15 PSI from elevation drop.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

4

Tuesday, May 21st 2013, 9:56am

a pressure tank might have saved the pump - it occurs to me that the pump is somewhat mismatched to the system

the Myers QP series are simple centrifugal pumps, for large flows at nominal pressure (about 60 gpm for a 1.5 HP model) but people often put in larger sizes than needed, because they want extra pressure

if something isn't right (like a zone valve not opening) in your sort of system, the pump is unprotected from rapid cycling, and it doesn't put out enough pressure to reliably employ a relief valve

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