WATER HEATER SYSTEM OPERATION
BME074000000T11
Water Heater System Starting Conditions
• The water heater system will start to operate when all of the following conditions are met:
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- Engine running (CKP sensor signal)
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- Ambient temperature less than 5 °C {41 °F} (IAT sensor No. 2 signal)
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- Water temperature less than 72 °C {162 °F} (Water temperature sensor)
Normal Operation
• The CPU in the water heater unit outputs a signal to the blower fan and fuel pump, which then deliver air and fuel to the unit.
• Within the unit, fuel is vaporized and mixed with air, and then sent to the combustion chamber.
• The mixture is ignited, by a spark from the glow plug, in the combustion chamber.
• Engine coolant temperature is raised as it circulates along the outside of the combustion chamber.
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1
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Blower fan
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2
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CPU
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3
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Vaporizer
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4
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Glow plug/Flame detection sensor
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5
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Combustion chamber
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6
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Burner
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7
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Water
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8
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Air
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9
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Fuel
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Full/half Switching
• Depending on the engine coolant temperature, the CPU sets the flame to either full or half strength settings.
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1
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Full mode
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2
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Half mode
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3
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Idle mode
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Fail-safe Function
• When the flame detection sensor detects that there is no flame, the CPU stops operation of the fuel pump.