GF83.70-D-2001HS Heater Operation, Function

GF83.70-D-2001HS Heater Operation, Function
MODEL 906.111 /113 /131 /133 /135 /153 /155 /211 /213 /231 /233 /235 /253 /255 /611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735
- with CODE (H12) Warm water auxiliary heater
- Stationary heater (STH) operation,
- stationary heater (STH)

MODEL 906.611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735
- with CODE (HZ5) 10 kW warm water auxiliary heater with timer
- Stationary heater (STH) operation,
- stationary heater (STH)

Since the stationary heater (STH) operation depends on the circuit status, the following function requirements exist for starting the STH heater operation:
- When the vehicle is standing with "circuit 15 OFF" status and when the fill level of the fuel tank is > 16 l
- When the vehicle is standing with "circuit 15 ON", "circuit 61 OFF" and when the fill level of the fuel tank is > 16 l

When the vehicle is standing with status "circuit 15 OFF" and when the fill level of the fuel tank is > 16 l
If the warm water auxiliary heating control unit (N33/3) receives the switch-on signal from one of the following two components, the STH heater operation is started immediately:
- STH Radio remote control (FFB), with code (HY1) Radio remote control for auxiliary heater
- Warm water stationary heater switch (S46/11)

If the STH heater operation is activated via one of the following two components, the system first wakes up the Controller Area Network bus class B (interior) (CAN-B) and then sends the message "VWZ_STH_MFL (timer status)" and the message "STHL_EIN_KOMBI (STH/ventilation On)" via CAN-B:
- Instrument cluster (A1), with code (JK3) High-end instrument cluster standard with speedometer in km
- Instrument cluster, except code (JK3) High-end instrument cluster standard with speedometer in km

After the warm water auxiliary heating control unit has received the messages, the STH heater operation is started immediately. STH heater operation activation is indicated by the red light emitting diode (LED) in the warm water stationary heater switch going on. The runtime of the STH heater operation is limited to t(max) = 1 h. If the status changes during the STH heater operation from "circuit 61 OFF" to "circuit 61 ON", the system switches over to heater booster (ZUH) operation and the runtime is unlimited until a status change to "circuit 61 OFF" takes place.

When the vehicle is standing with "circuit 15 ON", "circuit 61 OFF" and when the fill level of the fuel tank is > 16 l
With status "circuit 15 ON", the system wakes up the warm water auxiliary heating control unit via CAN-B. If the warm water auxiliary heating control unit does not receive a switch-on signal, the warm water auxiliary heating control unit "goes into sleep mode again.
Once the warm water auxiliary heating control unit receives the switch-on signal from one of the following two components, the STH heater operation is started immediately:
- STH FFB, with code (HY1) Radio remote control for auxiliary heater
- Instrument cluster, with code (JK3) High-end instrument cluster standard with speedometer in km
- Instrument cluster, except code (JK3) High-end instrument cluster standard with speedometer in km
- Warm water stationary heater switch

STH heater operation activation is indicated by the red LED in the warm water stationary heater switch going on. The runtime of the STH heater operation is limited to t(max) = 1 h.
If the status changes during STH heater operation from "circuit 61 OFF" to "circuit 61 ON", the system switches over to ZUH operation and the runtime is unlimited until a status change to "circuit 61 OFF" takes place.
The STH heater operation is subdivided into the following 4 sections:
- Startup phase
- Heating mode
- Control mode
- Caster

Startup phase
In the startup phase, the warm water auxiliary heating control unit actuates the glow pin (N33/3r1), the blower motor (N33/3m1) of the STH combustion air blower and the circulation pump (M13/4). The glow pin is responsible for preheating, the STH combustion air blower ensures ventilation of the combustor with downpipe, and the circulation pump ensures circulation of the coolant.
After t = 5 s, actuation of the blower motor of the STH combustion air blower is interrupted and the blower motor (M2) of the vehicle is actuated by the warm water auxiliary heating control unit. After t = 35 s, the blower motor of the STH combustion air blower is actuated again and after t = 42 s, the metering pump (M46/1) is actuated again by the warm water auxiliary heating control unit. The blower motor of the STH combustion air blower is responsible for the supply of combustion air, and the metering pump ensures the supply of fuel.
The supplied combustion air and the supplied fuel form an ignitable mixture, which is ignited at the glow pin.

If the warm water auxiliary heating control unit detects correct combustion in the combustor with downpipe via the flame sensor (N33/3b2) after t = 120 s, the stationary heater unit switches to "Heater operation". In addition, the warm water auxiliary heating control unit places the message "STH_EIN (STH switched on)" on the CAN-B. If the warm water auxiliary heating control unit does not detect correct combustion in the combustor with downpipe via the flame sensor after fuel has been supplied for t = 90 s, the start procedure of the stationary heater unit is repeated in the described manner. If the warm water auxiliary heating control unit does not detect correct combustion in the combustor with downpipe via the flame sensor after fuel has been supplied for another t = 90 s, a fault shutoff of the stationary heater unit takes place and the stationary heater unit switches to power-down mode.

After an impermissible number of fault shutoffs of the stationary heater unit, the warm water auxiliary heating control unit is locked.

If the glow pin is defective or the electrical line of the metering pump is interrupted, the stationary heater unit will not start.

Heating mode
During heater operation, the warm water auxiliary heating control unit interrupts actuation of the glow pin and continuously regulates the blower motor of the STH combustion air blower as well as the metering pump to a higher output. The ignitable mixture will now automatically ignite at the hot walls of the combustor with downpipe.
The warm water auxiliary heating control unit continues actuating the circulation pump and the blower motor of the vehicle.
The stationary heater unit is now set to power output stage "High (5 kW)".
During heater operation, depending on the actuation by the warm water auxiliary heating control unit, heater operation is regulated to "Control mode" in the power output stages "High (5 kW)" or "Low (2.4 kW)".

Control mode
During control mode, the warm water auxiliary heating control unit actuates, depending on the required power output stage "High (5 kW)" or "Low (2.4 kW)", the following components:
- Blower motor of the STH combustion air blower
- Metering pump

For vehicles except code (HH9) Regulated air conditioning (Tempmatic), the regulated operation depends on the coolant temperature, and for vehicles with code (HH9) Regulated air conditioning (Tempmatic), the regulated operation additionally depends on the temperature value set via the temperature selection switch (S98s14) integrated in the automatic air conditioning control and operating unit (S98).
The switch-on condition for the stationary heater unit is a coolant temperature of < 75 °C. At a coolant temperature of > 80 °C, the setting of the stationary heater unit is reduced to power output stage "Low (2.4 kW)".

If the coolant temperature increases to > 85 °C although the power output stage has been set to "Low (2.4 kW)", the stationary heater unit switches to a control break. In the control break, actuation of the blower motor of the STH combustion air blower and of the metering pump is interrupted by the warm water auxiliary heating control unit and the stationary heater unit switches to power-down mode for t = 130 s.
The circulation pump continues being actuated by the warm water auxiliary heating control unit. If the coolant temperature drops to < 75 °C, the blower motor of the STH combustion air blower and the metering pump are actuated again and the stationary heater unit switches to control mode again.
To this end, the warm water auxiliary heating control unit receives the messages of the following components via CAN-B:
- Coolant temperature sensor (B11/4)
- Interior compartment temperature sensor (S98b1) via the KLA control and operating unit, with code (HH9) Regulated air conditioning (Tempmatic)

If the warm water auxiliary heating control unit recognizes a flame-out via the flame sensor during heater operation or control mode, the start procedure of the stationary heater unit is repeated in the described manner. If, after a restart, the warm water auxiliary heating control unit does not detect correct combustion in the combustor with downpipe via the flame sensor after fuel has been supplied for another t = 90 s or if the flame goes out after t = 15 min after the heater has been operated again, a fault shutoff of the stationary heater unit takes place and the stationary heater unit switches to power-down mode.

The stationary heater unit fault shutoff can be canceled a maximum of 2 times by switching the stationary heater unit on and off.

If the warm water auxiliary heating control unit recognizes overheating (> 90 °C) of the stationary heater unit during heater operation or control mode via the overheating sensor (N33/3b3), then the actuation of the metering pump is interrupted; a fault shutoff of the stationary heater unit occurs and the stationary heater unit switches to power-down mode.
After the cause of the overheating has been eliminated and the stationary heater unit has cooled off (< 70 °C), he after operation can be restarted by switching the stationary heater unit on and off.
During the start phase, during heater operation and in control mode, the rotational speed of the blower motor of the STH combustion air blower is monitored by the warm water auxiliary heating control unit.
If the blower motor of the STH combustion air blower does not start up or if the rotational speed drops below 40 % of the specified value, a fault shutoff of the stationary heater unit occurs after t = 60 s and the stationary heater unit switches to power-down mode.

Terminate STH heater operation
The STH heater operation is terminated after the runtime of t(max) = 1 h has elapsed, after a status change from "circuit 15 ON" to "circuit 15 OFF" or after reception of the shutoff signal, which the warm water auxiliary heating control unit receives from one of the following components:
- STH FFB, with code (HY1) Radio remote control for auxiliary heater
- Instrument cluster, with code (JK3) High-end instrument cluster standard with speedometer in km
- Instrument cluster, except code (JK3) High-end instrument cluster standard with speedometer in km
- Warm water stationary heater switch

After STH heater operation has ended, the stationary heater unit switches to power-down mode.

Delayed-off running
In power-down mode, the warm water auxiliary heating control unit actuates the blower motor of the STH combustion air blower and the circulation pump for t = 120 s as well as the glow pin for t = 20 s. The blower motor of the STH combustion air blower is used to cool off the combustor with downpipe of the stationary heater unit through the generated air suction and to discharge combustion gases. The circulation pump is used to cool off the heat exchanger of the stationary heater unit through the coolant flowing by. The glow pin burns itself off during this time.

The warm water auxiliary heating control unit places the message "STH_EIN (STH switched on)" on the CAN-B until the power-down mode has been terminated.