Method and apparatus for energising a solenoid of a valve assembly

There is provided a method of energising a solenoid of a valve assembly, comprising the steps of applying a positive over boost voltage to the solenoid to actuate a moveable plunger to open or close a flow path through the valve assembly, and then applying a negative braking voltage to brake the movement of the plunger during movement of the moveable plunger. There is also provided a method of energising a solenoid of a valve assembly, the method comprising the steps of receiving a demand signal to actuate the valve, applying a wait time after receipt of the demand signal, applying a positive over boost voltage across the solenoid to actuate a moveable plunger to open or close a flow path through the valve assembly, monitoring the solenoid closure time, and adjusting one or more input variables in order to control the solenoid closure time. There is also provided a method of monitoring the solenoid closure time over a plurality of different energising and de-energising cycles of the solenoid and generating an output to indicate a need for valve maintenance. Finally, there is provided a controller and a valve assembly configured to perform these methods.