[SherwoodCleaningSe]

I'd say it's always a good idea to remove a pressure switch from the circuit.  I had the pressure switch wired in with my varistream one day the thing wouldn't work, the pressure switch had burnt out and stopped power getting to the varistream, bypassed the pressure switch and it was fine.

Simon.

[MartinB]

If a pressure switch is not disconnected, and its shut off pressure is lower than the Varistream, then it will be the switch which turns the pump off not the Varistream.

One of the main features of the Varistream is to take the pressure switch out of the equation and therefore eleviate burnt out switches.

To ensure your system performs correctly with the Varistream, always disconnect the pump pressure switch.