Service Manual

Page 30
4.9 Water Valve
The inlet water valve contains the flow sensor responsible for the flow rate detection and a motor
stepper responsible for the maximum water flow control through the unit.
Figure 23 – Inlet Water Valve
Water flow is measured by a turbine flow sensor that is fed by a DC signal and gives a feedback
signal proportional to the measured water flow (see Table 9).
• Minimum Flow rate to start up the appliance: 0.45 gpm (1.7 l/min)
• Flow rate to shut off the appliance: < 0.5 gpm (1.8 l/min)
In case Q > min start up flow following P
out
verification occurs:
• If Pout > Minimum Power, the appliance will run with the calculated minimum water flow, in order
to reach the set point with a temperature stability of +/- 2ºF (+ / - 1ºC);
• If P out < Minimum Power, the T out is assured by a pulsating burner mode + cold water mixing
(easy minimum).
Table 9 – Water Flow Sensor Values
Flow [l/min]
Flow (g/min)
Frequency [Hz]
27
7.13
108
24
6.34
96
18
4.75
72
14
3.69
56
10
2.64
40
8
2.11
32
4
1.05
16
2
0.52
8
30