Heat mode when 50 to 100% of heating capacity is required

S83.70-1016-09

The start of heater operation is completed. The combustion air blower (11) and fuel metering pump (1) deliver at their lowest output in "Part load operation".

If the heat requirement increases, the coolant temperature drops. The heat output must be increased by cooling down the coolant. The thermostat (5) in the coolant circuit signals to the control module (3) that the hot water auxiliary heater (A34) must be switched over to "Full load operation".

The coolant temperature increases again in this operating condition of the hot water auxiliary heater (A34).

If the temperature increases above 80°C, the heat requirement drops and the heat output must be reduced.

The control module (3) receives a signal via the thermostat (5) to switch over the hot water auxiliary heater (A34) to "Part load operation".

The combustion air blower (11) and the fuel metering pump (1) then work in "Part load operation". The combustion air blower (11) reduces its speed down to 1/4 of the maximum speed.

In this operating condition of the hot water auxiliary heater (A34), heat is again removed from the coolant and the coolant temperature drops further. The coolant circulation pump (8) and the vehicle heater blower continue operating.

As the coolant temperature drops the heat requirement increases again. The thermostat (5) signals to the control module (3) that the hot water auxiliary heater (A34) must be switched to "Full load operation" and the full cycle of the heater operation starts all over again.

This change between "Part load and full load operation" continues throughout the period of heater operation when the heat requirement remains unchanged.