Heater unit description

HEATER UNIT DESCRIPTION

The centre section of the unit consists of a diesel burner inside of which the flame develops and a heat exchanger coaxial to it in which the water circulating in the system is heated

There is also a heater plug required for combustion an air fan which draws in air through a special out side pipe and provides the air needed for combustion Lastly the heater unit is completed by the electronic control unit a sensor which measures the temperature of the coolant and sends a proportional signal to the electronic control unit a photo cell which detects the presence of the flame and provides a signal for the electronic control unit and a thermal switch which has the task of sending the control unit a signal to cut off the supply of fuel if the temperature in the heater casing becomes too high

There is also a fuel metering pump outside the heater unit which operated by the control unit takes the amount of fuel from the vehicle system required for the correct metering in the burner in the various operating conditions

HEATER UNIT OPERATION

Determining the need for the additional heater

The control unit determines the need to heat the engine coolant during starting

Versions with automatic air conditioning are equipped with an outside air temperature sensor which measures the outside temperature conditions and sends them to the climate control unit which in turn sends them to the engine management control unit On versions with manual air conditioning the outside temperature is measured by a sensor inside in the flow meter and is sent to the engine management control unit In both cases the additional heater unit takes the outside air temperature signal from the engine management control unit

The diagram below illustrates the operating range of the additional heater

1. Ta = Outside air temperature
2. Te = Engine coolant temperature
3. A = Additional heater operating range