January 2001
5A - 25
Functions - Water System
Service Manual Cafitesse 500
Fig. 1
2
5
1
3
4
6
Opening and closing the valve
●
Water pressure is on both sides of the
diaphragm. A compensation of the pressure
is affected by a very small opening in the
diaphragm.
●
This compensation hole (1) is pierced by a
cleaning needle (2). (Fig. 1)
Thus every time the valve opens, i.e. every
time the diaphragm moves, the
compensation hole is cleaned.
●
There is a higher pressure on the upper
diaphragm side (3) than on the lower
diaphragm side, as there is no water
pressure on that part of the lower side
which is covered by the outlet spout.
(Fig. 1)
●
In this way, the diaphragm keeps the outlet
spout closed.
●
If an electric current is applied to the coil,
the tappet (4) is withdrawn and the bore (5)
in the middle of the diaphragm is opened.
(Fig. 1)
Water can flow through it from the upper
part.
●
As the pressure compensation hole is much
smaller than the opening in the middle of
the diaphragm, the pressure cannot be
compensated any more.
●
The pressure on the upper side of the
diaphragm decreases in contrast to the
water pressure on the lower side.
●
This causes the diaphragm to move
upwards and open the outlet spout.
●
Water is running from the water supply line
through the valve.
●
As soon as the current supply to the coil is
interrupted, the tappet closes the centre
opening which causes the pressure on the
upper side of the diaphragm to increase.
●
The valve closes.
Additional spring
●
The additional spring (6) which presses
onto the upper side of the diaphragm, only
slightly influences the function of the valve.
●
The spring effects, however, a faster
closing which enables a more precise level
regulation in the boiler.
●
The additional spring also prevents water
from flowing out of the boiler if the water
supply line is disconnected.
