THERE ARE TWO FLOW SWITCHES, 1 FOR THE HOT WATER ON THE LEFT HAND SIDE, 1 FOR THE CENTRAL HEATING ON THE RIGHT! YOU HAVE TO TAKE OFF THE LARGE BOILER COVER, THEN DROP DOWN THE LOWER PANEL TO GET AT THE MAIN WORKINGS OF THE BOILER.
THE FLOW SWITCHES ARE BLACK WITH 2 WIRES GOING INTO THE TOP OF THEM, THE WIRES HAVE A PLUG TO DISCONNECT, ABOUT 2 INCHES DOWN THE WIRE FROM THE FLOW SWITCHES.
HOPE THIS HELPS
ANDREW DICKINSON
July 2007