What to do when a shower pump turns on by itself
If your pump is starting up on its own there are few things you need to consider.
First determine if you have a universal (negative head) pump. These pumps are easily identified by a pressure vessel on the top of the pump.
A universal (negative head) pump turn on when they recognise a pressure drop in the system. A dripping tap or leak in the system can cause the system pressure to drop which would activate a negative head pump, even though all outlets are turned off. This is called ‘hunting’. When a pump is ‘hunting’ you will hear the pump switch on for a few seconds when no outlets are open. Find out how to test if your pump is hunting.
A positive head pump doesn’t have a pressure vessel. These pumps are activated by a flow switch set to turn the pump when a natural flow rate (without assistance from the pump) of 2 litres per minute passes through the pump.
If you have a positive head pump that is turning on and off during use, this is most likely due to the water flow rate being insufficient to activate the pump.