The auxiliary fuel fired heater is mounted on the coolant supply line to the heater assembly and is located behind the right wing mudguard. The two electrical connectors on the heater block are designed to connect it to the vehicle's electrical system.
FFBH includes the following elements:
- Air blower
- Combustion chamber housing
- heat exchanger
- Air intake hose with silencer
- Exhaust pipe with silencer
- control module
Sectional view of a typical fuel-fired auxiliary heater:
| Pos. | spare part no | Name |
| 1 | - | Combustion chamber fan |
| 2 | - | coolant outlet |
| 3 | - | coolant inlet |
| 4 | - | Refractory insert |
| 5 | - | heat exchanger |
| 6 | - | temperature sensor |
| 7 | - | Release |
| 8 | - | fuel inlet |
| 9 | - | Evaporator |
| 10 | - | Air inlet |
Combustion chamber fan
The combustion air blower controls the air supply to the FFBH to keep the fuel supplied from the auxiliary fuel pump burning. It is also used to purge and cool the FFBH.
Combustion chamber housing
The combustion chamber housing contains a refractory insert, as well as a connector for connecting an exhaust pipe and fittings for connecting a hose from an additional coolant pump to the pump and a hose to the heater radiator.
The refractory insert includes a fuel combustion chamber, as well as an evaporator and a glow plug with a flame sensor. Fuel from the auxiliary fuel pump is fed into the diffuser, where it evaporates and then is fed into the combustion chamber, where it mixes with air from the combustion air supply fan. A glow plug with a flame sensor provides the initial ignition of the air-fuel mixture, and after the combustion process has stabilized, controls the flame.
Heat exchanger
The heat exchanger transfers the heat generated in the combustion chamber to the coolant. Two temperature sensors installed in the heat exchanger housing provide information about the engine coolant temperature to the control module. The management module uses this information to manage the system.
Air intake hose with silencer
An intake silencer is installed in the intake air hose. The muffler is designed to reduce intake noise.
Exhaust pipe with silencer
The muffled exhaust pipe vents combustion products to the atmosphere at a point located under the right front wheel arch. During operation of the FFBH module, steam may be observed at the outlet, depending on weather conditions.
Control module
The control module controls and monitors the operation of the FFBH. To protect the control module from overheating, the air flow generated by the combustion chamber fan is used.
The control module receives constant power from the battery junction box (BJB), and communicates with the PBX module via the medium-speed CAN bus.
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