P83.70-0257-11
The task of the STH control unit (A6n1) for models 129, 203, 209, 215, 230 or the STH or ZUH control unit (A6n1) for models 168, 202, 210, 220 or the STH and ZUH control unit (A6n1) for model 463 is to control and monitor overall heater operation:
Monitoring the signals from the glow pin unit flame monitor in its function as flame monitor and internal coolant temperature sensing,
monitoring cut-in with a starter lockout depending on internal coolant temperature sensing in the case of the heater booster,
Actuation of the combustion air blower, the circulation pump, the external fuel metering pump and the heater fan
malfunction shutoff in the event of extraordinary operating conditions such as flame discontinuation, undervoltage or overvoltage, failure of internal coolant temperature acquisition
malfunction shutoff and locking in the event of overheating.
The internal coolant temperature recording is integrated into the STH control unit (A6n1) or the STH or ZUH control unit (A6n1). In the event of a malfunction or a defect, the control unit/heat exchanger unit must be replaced.