Service Manual

Page 38
Ionization Electrode
Flame is sensed through an ionization electrode, and detection is granted for ionization currents higher
than 0.5 µA. The two ionization electrodes are spaced to allow flame detection on both sides of the
burner.
5. Working Principle / Electric Measurements
Water Flow Detection and Solar Mode Operation
Operation Action
Connection to
the control unit
Result
Standby
(Inputs signals must
be within expected
limits)
Flow Sensor
Input
ON
Electrical plug connected Input
120 V
AC
60 Hz
Thermal fuse with
continuity
Input Contact closed
Ionization reading
Input
0 µA
Temperature sensors OK Input
Ohm Value inside
range
Hot Water Demand
(tap opening)
Turbine detects water
flow
Input
Frequency value
to control unit
Spark to ignition
electrodes
Output
Gas valve solenoid
activation
Output 13 V
DC
Flame on main burner
Ionization detection
(spark stops)
Input I > 0.5 µA
Hot Water Delivery
Safety devices monitor
operation
Input
Table 10 – Minimum Operation Conditions Signals
Water Flow Calculation
Procedure
Water Flow = Power
(T
set
– T
in
)
Flow ≥ 0.45
Burner ON
Flow < 0.45
Burner OFF
Burner On
Solar Mode Operation
Burner Off
T
in
≥ T
set
– 1ºC
T
out
< T set
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