GF83.70-D-0005H Heater Booster, Function

GF83.70-D-0005H Heater Booster, Function

- with CODE (HZ9) Heater booster, diesel

Heater booster (ZUH)

The heater booster (ZUH) system is installed in vehicles with engine OM642 and engine OM646. These engines are unable to provide sufficient heat for heating the passenger compartment immediately after the starting procedure, particularly during the winter, which is why they require the assistance of a heater booster.
The heater booster heater unit is the main component of the HB system and can only be activated with "circuit 61 ON" when the engine is running. The heater booster heater unit is a compact water heater that is connected to the engine coolant circuit. The heater booster heater unit is available in the "D5WS (= diesel operated)" variant by Ebersp�cher.

New USA exhaust emission legislation as of 01/2010:
Operation of the stationary heater is only possible with outside temperatures < 4 °C (39.2 °F).

The heater booster heater unit consists of the following components:
- Heat exchange
- Combustor with downpipe
- Warm water auxiliary heater 2 control unit (N33/2)
- Temperature sensor (N33/2b1)
- Flame sensor (N33/2b2)
- Overheating sensor (N33/2b3)
- Blower motor (N33/2m1) of HB combustion air blower
- Glow plug (N33/2r1)

In addition to the heater booster heater unit, the HB system needs the following two components:
- Metering pump (M46/4), for fuel supply
- Circulation pump (M13/4), to circulate the coolant

The ZUH system and thus the heater operation of the heater booster heater unit is activated via the stationary heater switch (S46/10). By actuating the stationary heater switch in the upper subfield, the heater operation of the heater booster heater unit is activated via the warm water auxiliary heater 2 control unit.
The heater operation of the heater booster heater unit remains activated until the stationary heater switch in the upper subfield is actuated again.

The stationary heater switch has a "Memory function" (automatic heater operation activation of the heater booster heater unit). The "Memory function" remains active (also in the event of a status change of circuit 15 and circuit 61) until it is deactivated again by operating the stationary heater switch in the upper subfield.