Nilfisk-ALTO NEPTUNE 4 FA Service Manual page 26

Function
D
If the main switch (S1) is set to "Hot water" mode with the spray device open, and the required tem-
perature is subsequently preset with the same switch, if the temperature sensor (B1) is within set
limits, if the level sensor (B9) signals that there is sufficient fuel in the tank and the flow indicator
(B2) determines adequate volume flow in the system, the processor turns on the burner motor (M2),
the anti scale pump (Y3) and the ignition transformer (T2) across the burner relay (K2). A high-
voltage ignition spark is generated on the ignition electrodes in the burner. The burner motor (M2)
blows preheated air through the burner fan into the heat exchanger. The self-intaking fuel pump
conveys fuel under pressure to the solenoid valve (Y1).
After 1 s of preventilation the solenoid valve (Y1) opens and fuel reaches the fuel nozzle. In the bur-
ner it is atomized and ignited. The fuel pressure is applied on a line to the dosing device of the anti-
scaling valve. This opens and, depending on how it is set, conducts anti-scaling concentrate into the
water break tank. The setting of the dosing device is a function of water hardness.
The flame sensor (B7, if installed and activated) checks whether the fuel/air mixture is ignited and
allows the burner to continue running. If there is no flame 4 s after starting "Hot water" mode, the
solenoid valve closes and the burner is turned off without postventilation.
Depending on the setting of the SDR valve (selection, dosing and rinsing), the high-pressure pump
intakes detergent. Detergent alone is only drawn in by the foot valve in the maximum setting. Other-
wise the volume drawn by the pump is a water/detergent mixture.
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