The pressure switch is used to switch the pump drive motor off when the pump system is up to its required pressure, when all of the valves are closed and their is no further demand for water. The pressure tank stores a volume of water so the pump will not start if the system settles or leaks slightly.
In this example the pressure switch is the black box under the pressure tank.
Always disconnect the power supply from the pressure switch and test with a multimeter to ensure the switch is not live before removing the cover.
A correctly charged pressure tank and correctly set pressure switch will allow the pump to shut off when there is no demand for water and restart when the pressure drops due to a demand or requirement for more water.
The pressure switch contacts should remain closed and the pump running while the demand for water is present. That means the pump will run constantly while filling the tank or watering the garden. If the pressure switch is out of adjustment the pump will stop and start and cycle between on and off while in use. This condition of cycling or rapid cycling will damage the pump and motor and consume a large amount of power.
Adjustment of the pressure switch is made while the power is isolated from the pump.
To increase the cut out pressure of the Telemechanique XMP pressure switch turn the large thumb dial clockwise. Reconnect the power and allow the pump to run in its normal operating condition. If the pressure switch allows the pump to cycle on and off unnecessarily. Isolate the power and increase the pressure further.
Always check that the pump can reach the set cut out pressure and stop when the valves are closed.
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