How Do Pressure Well Pump Switches Work?

Float Switch

Open tank float switches (floating pressure well pump switches) operate at about 115 volts to 230 volts per switch. These switches behave just like a mechanically-operated switch. When well water rises, the floating pressure well pump switch automatically opens electrical contacts. This action manages tank fill up. When the well tank is at maximum capacity, the float switch shuts the water pump off.

Low Pressure Switch

The low pressure well pump switch has a built in cut-off switch. This means that a drop in pressure (factory settings vary) will activate a shut-off of the pump. Low pressure well pump switches have to be reset by hand to restart the water pump after a shut-off. A typical setting for low pressure switches is about 20 pressure per square inch (switch on), and 40 pressure per square inch (shut-off point). A temperature sensor is commonly installed in the form of a heat switch for the pump chassis. In the event that temperatures exceed 120 degrees F, the power to the pump is shut off. Like the pressure switch, the heat sensor will restart the pump after the temperature cools down (by about 10 degrees difference).

Hardware

Pressure well pump switches convert a psi signal to electrical output. The pressure on the water tank tells the elastomeric diaphragm to open or close the circuit. The psi signal is determined by setting an adjustable pressure point. Typically, the pressure switch will include an indicator with a scale, with hard keys for setting the pressure tolerance on the unit. The elastomeric diaphragm replaces the oil barrier in modern water pressure switch design. The interlock mechanism is a water column used to detect water pressure at a specific tolerance level inside of the well water tank. The pressure well pump switch is mounted near the well with pressure fitted steel or molded plastics, commonly referred to as pressure fittings, securing the switch to a wall. Turning the switch on starts the jet at the base of the well, and an impeller that levies the water up the well. Deep pressure wells will have a switch that stops the water pressure around 40 to 60 psi. The switch itself will be either near or on the power box, or it will take the form of a lever at either side of a main switch box near the water tank (usually in the garage, basement or side of the residence).