Safety Thermal Temperature Sensor In Boiler Exhaust - Nilfisk-ALTO Neptune PE Service Manual

The safety thermal release mounted on the heat exchanger water inlet, is an absolute safety
element on the heat exchanger.
If a fault is present, e.g. all control and safety devices fails, and hot water flows at high pres-
sure from the heat exchanger back through the safety valve into the high pressure pump, the
thermal release responds and shuts down the entire machine through the control circuit. Be-
fore restarting, the machine must cool down, the fault causing the heated water to flow in the
wrong direction must be corrected, and a new thermal release fitted.
NEPTUNE PE-DE_en_Ver.1.0_October 2010
Function

Safety Thermal Temperature Sensor in boiler exhaust

Located in the heat exchanger outlet (flue) is a tempera-
ture-dependent resistor (Pt 100) functioning as a tem-
perature sensor.
If the temperature in the heat exchanger outlet (actual
temperature) exceeds the temperature set-point, the so-
lenoid valve Y1 closes to interrupt the fuel feed. The
temperature sensor is only activated in "Hot water"
mode.
The flame sensor is a light-sensitive phototransistor.
The flame sensor checks for the presence of a flame.
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