Espresso Pump - Low-Pressure-Ready - WMF espresso Service Manual

Service
2.6

Espresso pump - low-pressure-ready

The WMF espresso generally comes with an integrated low-pressure-ready balanced espresso pump.
This espresso pump, unlike standard non balanced espresso pumps, controls the brewing pressure to the set level, regardless of the pump inlet pressure.
"Low pressure" is deactivated in the software by default; the coffee machine operates in normal mode. This means
 The espresso pump only operates for coffee servings
After "Low pressure" is activated in the software, the coffee machine operates in normal/low pressure mode, irrespective of the pump input pressure
(= line pressure):

Pressure switch activated > 2.7 bar ± 0.1 = normal operation:
The espresso pump only operates for coffee servings.

Pressure switch not activated < 2.7 ± 0.1 = low pressure operation:
Espresso pump runs when making coffee and when filling the boiler, and for hot water servings.
Important note for technicians / Note to customer
 The espresso pump is NOT self-priming.
 If the espresso pump runs dry, there is a risk that it will be damaged.
 The coffee machine must therefore have an upstream pressure on the line side of 0.2 bar. This means:
 Under no circumstances must the coffee machine be operated with an external tank which does not have a supply pump between it and the machine.
 If low-pressure is activated in the software, a flow meter evaluation triggers the message "Open water supply" during the coffee servings, and not the
pressure switch. At present, NO evaluation takes place during boiler filling, and hot water servings; the message "Open water supply" does NOT appear
 If the customer is not able to guarantee the on-site line pressure specified in the planning information and if the low-pressure option is selected, the
customer must refer to the above information/the customer MUST ensure that the water tap is open before serving.
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