Pressure Switch Merrill 30/50

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Pressure Switch Merrill 30/50


Submersible or Jet Pump 115v or 230v

Pressure Settings:

Factory Set at 30/50

Can be easily adjusted to 40/60 20/40 or any other setting.

Has separate differential adjustment to raise or lower cut out pressure without changing cut in pressure.

Important: Air Charge in pressure tank should be set to 2-4 PSI below cut-in pressure of switch to achieve maximum drawdown of tank and avoid short cycling of pump. The higher the pressure setting is set at will lower the overall drawdown capacity of the pressure tank will be. Failure to adjust the air charge properly can cause the following problems:

Air Charge too Low: Pump will cycle frequently because the pump will come on before tank is drawn down.

Air Charge too High: Tank will draw down completely and pressure will drop off before the pump kicks back on.

If your switch is short cycling(rapidly turning on and off) it is probably due to the fact that your pressure tank is failed and is not a switch malfunction. Always check the air charge in the tank with a tire pressure gauge with the pump off and water pressure drained from the lines.



Available Models:

  • MPS3050 - Standard

  • MPSM43050* - w/ Pump Protection Low Pressure Cut Out

*Pump Protection Model:
Switch will mechanically shut off power to pump if line pressure drops 10 PSI below cut-in pressure and will need reset manually.
Lever on side needs to be raised just enough for contacts to make until line achieves set cut-in pressure then it can be released. This will need to be done on start-up after switch is installed and whenever the line pressure drops 10 PSI below cut-in pressure to protect the well pump motor.
If lever is raised all the way up switch will turn off.
The Pump Protection Model is not recommended in installations where the pressure frequently drops 10PSI below the cut-in pressure(Ex. Old worn out Jet Pump or Undersized Pump) because it will cause frequent of nuisance trips and will need manually restarted.

Application: Water Well