Sprinkler Pump Low Pressure Switch

[Steven Shaffer]

Hello All,

If this post is better suited to Sprinklers and Irrigation Sub please tell me. This issue is pump related albeit a sprinkler pump.

My sprinkler pump shuts off randomly. This happens on the “auto” setting, so I am by passing any timers.

Today I replaced 2 old wires on the low pressure switch. They were old and burned. The strange thing is that this had no effect on the pump. It worked intermittently before changing the wires and worked intermittently after changing the wires. I’ve attached pictures for review. The 2 wires I replaced are supposed to supply electricity to the motor (denoted by a yellow M). These wires are attached to the 2 brass screws in the middle. The 2 wires with a green check mark have power. The 2 wires with a red X do not have power. Any suggestions?

Just to clarify, the system pressure is constant at 50 psi. When the pump is working, the motor is spinning and all sprinklers are shooting water. When it shuts off the motor does not spin and there is no water coming out of the sprinkler heads.

 

[RS]

The switch you have looks like a pressure control switch, and they shut the pump off when it reaches a setpoint. Some have a low pressure cut off the prevent the pump from running when there's no water, that has to be reset manually. First of all, I would clean the points in the switch, and if it still cuts off I would tighten the bit adjusting nut 2 revolutions, and see what happens. Let us know what you find.

 

[Valveman]

When using a pump start relay you should not be using the pressure switch. If it gets about 50 or so the pressure switch will shut it off, and it should not. Most sprinkler pumps don't even build enough pressure to work with pressure switch. They will run the sprinklers at 50 PSI, but can't make 60 for the pressure switch to work.

 

[Steven Shaffer]

When using a pump start relay you should not be using the pressure switch. If it gets about 50 or so the pressure switch will shut it off, and it should not. Most sprinkler pumps don't even build enough pressure to work with pressure switch. They will run the sprinklers at 50 PSI, but can't make 60 for the pressure switch to work.

Hi Valveman,

Thank you for the reply. The L2 in and L2 out don’t have power (no power at the start relay or the low pressure switch). the L1 in and L1 out do have power and are sending it down to the motor. The motor hums when we turn on the power but doesn’t spin. Could the fact the L2 in and L2 (no power) be the culprit?

 

[Steven Shaffer]

The switch you have looks like a pressure control switch, and they shut the pump off when it reaches a setpoint. Some have a low pressure cut off the prevent the pump from running when there's no water, that has to be reset manually. First of all, I would clean the points in the switch, and if it still cuts off I would tighten the bit adjusting nut 2 revolutions, and see what happens. Let us know what you find.

Hi RS,

Thank you for your reply. The problem has been solved. The blue pressure tank on top of the motor was repressureized to 30 PSI. I flipped the switch and by god the pump turned on. The L2 in and L2 out still don’t have power. I have no clue why this made the pump work.

How did you learn all this pump info? Thanks again for your help!

 

[MicEd69]

Hi RS,

Thank you for your reply. The problem has been solved. The blue pressure tank on top of the motor was repressureized to 30 PSI. I flipped the switch and by god the pump turned on. The L2 in and L2 out still don’t have power. I have no clue why this made the pump work.

How did you learn all this pump info? Thanks again for your help!

It appears you are running the motor on 115 volts. That switch can be used in a 115- or 230-volt circuit. The green checked lines are the power side, and the red X lines are the neutral side. In a 230-volt circuit, both sides would have power when the solenoid is pulled in.

 

[RS]

The switch you have looks like a pressure control switch, and they shut the pump off when it reaches a setpoint. Some have a low pressure cut off the prevent the pump from running when there's no water, that has to be reset manually. First of all, I would clean the points in the switch, and if it still cuts off I would tighten the bit adjusting nut 2 revolutions, and see what happens. Let us know what you find.

The BIG adjusting nut, the one with the long spring under it, sorry for the typo!

When using a pump start relay you should not be using the pressure switch. If it gets about 50 or so the pressure switch will shut it off, and it should not. Most sprinkler pumps don't even build enough pressure to work with pressure switch. They will run the sprinklers at 50 PSI, but can't make 60 for the pressure switch to work.

I have a pressure switch on our sprinkler system, and a pressure tank, set up just like a well system, the switch is set to 20-45, that way if I forget to shut the pump off when all the zones are done the pup shuts off automatically. We have 3 zones, with about 15 heads per zone, so the pump runs steady at about 40 psi when watering. I don't have the system set up to start automatically, if the lake is rough and the water dirty I don't want to run it, I start and stop the pump with the breaker in the panel. Most pressure switches I have dealt with can be adjusted to any pressure within it's range. I have use well pump switches on air compressors up to 110 psi.

 

[Valveman]

The BIG adjusting nut, the one with the long spring under it, sorry for the typo!

I have a pressure switch on our sprinkler system, and a pressure tank, set up just like a well system, the switch is set to 20-45, that way if I forget to shut the pump off when all the zones are done the pup shuts off automatically. We have 3 zones, with about 15 heads per zone, so the pump runs steady at about 40 psi when watering. I don't have the system set up to start automatically, if the lake is rough and the water dirty I don't want to run it, I start and stop the pump with the breaker in the panel. Most pressure switches I have dealt with can be adjusted to any pressure within it's range. I have use well pump switches on air compressors up to 110 psi.

Yeah but some sprinkler pumps that run at 50 PSI won't build 55 for a pressure switch. Also have to make sure there are no leaks if you don't turn it off, and to use enough sprinklers to prevent cycling the switch. Even hard for a relief valve to save a sprinkler pump if the pump doesn't go off when the sprinklers quit.