Regulate heater operation, function

W83.70-0109-06

1 Heater unit

2 Heating air inflow vents

3 Combustion and heated air blower

4 Control IC

5 Flame sensor

6 Glow pin

7 Burner insert

8 Temperature limiter

9 Afterburner pipe

10 Heat exchanger

11 Fuel metering pump

12 Timer

13 Rotary potentiometer

A Exhaust

HA Heater outlet

HE Heater inlet

V Combustion air

Control mode

 The heater's (1) heating mode is switched on at the timer (12).

 The heater (1) has run through the starting phase and is now in the control mode. The combustion gases heat up the heat exchanger's (10) internal wall and the aspirated heated air, which flows around the outside of the heat exchanger (10) and heats up. The heater (1) retains the maximum output for as long as it takes until the aspirated heated air has reached the set room temperature. Heating output is then reduced. The controller board (4) regulates the combustion and heated air blower (3) to 60 % of maximum speed and additionally the clock frequency for the fuel metering pump (11) proportionally, until the set room temperature is exceeded.

 If the temperature set on the timer (12) is exceeded and the minimum heater output held for longer than 5 seconds, the controller board (4) switches off the fuel metering pump (11) and terminates the combustion process.

 During the power-down phase, the combustion and heated air blower (3) runs on for another 155 seconds at 60% of maximum speed, in order to cool and purge the heater (1).

Control interval

 After expiration of the power-down phase the heater (1) goes into the control interval mode.

 The combustion and heated air blower (3) continues to run at minimum speed and routes air from the cab past the temperature sensor on the controller board (4).

 Once the temperature drops below that set on the timer (12) a new starting procedure is initiated without a breakaway torque. The heating mode starts again.