Expobar Tank Switch
Expobar Tank Switch
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The microswitch below the cold water tanks is normally wired as shown above and switches the machine off when about 15-20% full, this protects the pump/machine from damage, should the autofill operate with an empty tank.

If you change the wiring to the tank microswitch and move the lower wire to the bottom connector as shown in the second picture, the machine will operate from empty to around 25% full and then switches off if the tank is more than 25% full. This is ideal for mains plumbed operation and also if you re-route the OPV vent tube to the tank, as it will switch off before the tank overflows.