Hydraulic Scheme - Foster 2998100 Service Manual

SERVICE MANUAL – Coffee Machine mod. 2998100 - 2998600
HYDRAULIC SCHEME
The circuits for hot water, steam and coffee are fed by the same vibration pump; therefore, their supply
happens separately.
Hereafter is a short description of the operating sequences concerning the four main functions:
Coffee supply:
By pushing the coffee button, the cycle of supply is initiated with the start of the pump P1 and two
electro-valves EV2 – EV4. The electro-valve EV2 is connected to the hydraulic piston which reaches
operating pressure by closing the infusion chamber on the drawer filter. At the same time, the electro-
valve EV4 is opened and allows passage of pressured water through the non-return valve VR1, set to
open at the optimal supply pressure. Water passes through the coffee exchanger and flows in the
infusion chamber at the operating temperature only if the mechanical sensor of pod presence is open,
that is if the pod is present on the filter. To stop the supply, press the coffee button again. The pump P1
is stopped at the same time as the electro-valve EV2, while the electro-valve EV4 enables the drainage
of water in the drop-receptacle basin through the silicone pipe.
Hot water supply
When pressing the hot water button, the pump P1 and the electro-valves EV1 and EV4 are activated.
Water flows through the two electro-valves and is heated by the coffee exchanger, then flows through
the moveable supply pipe. When the required quantity is reached, to stop the supply press the hot
water button again. The pump and the two electro-valves are stopped and the water in excess still
present in the coffee exchanger flows back through EV4 and back in the drop-receptacle basin through
the silicone pipe.
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