FBH System (Where Fitted)

FBH system (where fitted)
The FBH system operates only while the engine is running and the ambient temperature is less than 5 degrees C (41 degrees F). With the engine running and the ambient temperature below 5 degrees C (41 degrees F), the air temperature sensor connects the alternator power supply to the ECU in the FBH unit. On receipt of the alternator power supply, the ECU starts the circulation pump and, depending on the input from the temperature sensor in the heat exchanger, enters either a standby or active mode of operation. If the heat exchanger casing temperature is 65 degrees C (149 degrees F) or above, the ECU enters a standby mode of operation. If the heat exchanger casing temperature is below 65 degrees C (149 degrees F), the ECU enters an active mode of operation. In the standby mode, the ECU monitors the heat exchanger casing temperature and enters the active mode if it drops below 65 degrees C (149 degrees F). In the active mode, the ECU initiates a start sequence and then operates the system at full or part load combustion to provide the required heat input to the coolant.