VUW 30/36CS/1-5 (N-GB) ecoTEC plus 836

• Fault in the electrical connection for the flow temperature sensor
• Flow temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the flow temperature sensor.

• Fault in the electrical connection for the return temperature sensor
• Return temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the return temperature sensor.

• Fault in the electrical connection for the domestic hot water temperature sensor
• Domestic hot water temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the domestic hot water temperature sensor.

• Fault in the electrical connection for the cylinder temperature sensor
• Cylinder temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the cylinder temperature sensor.

• Fault in the electrical connection for the flow temperature sensor
• Flow temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the flow temperature sensor.

• Fault in the electrical connection for the return temperature sensor
• Return temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the return temperature sensor.

• Fault in the electrical connection for the domestic hot water temperature sensor
• Domestic hot water temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the domestic hot water temperature sensor.

• Fault in the electrical connection for the cylinder temperature sensor
• Cylinder temperature sensor defective

Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the cylinder temperature sensor.

• Insufficient/no water in the product.
• Fault in the electrical connection for the flow temperature sensor
• Fault in the electrical connection for the return temperature sensor
• Flow temperature sensor defective
• Return temperature sensor defective
• The pump is defective.
• 3-port diverter valve defective or blocked
• Water pressure sensor defective
• Volume flow sensor defective
• Black discharge via the ignition cable, ignition plug or ignition electrode

Fill the heating installation. Check the product and the system for leakages. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the flow temperature sensor. Check and, if required, replace the return temperature sensor. Check and, if required, replace the pump. Check and, if required, replace the 3-port diverter valve. Check and, if required, replace the water pressure sensor. Check and, if required, replace the volume flow sensor. Check the ignition cable, ignition plug and ignition electrode.

• Insufficient/no water in the product.
• Fault in the electrical connection for the water pressure sensor
• Cable for the pump/for the water pressure sensor is loose/not connected/defective
• Water pressure sensor defective
• Pump operation interrupted
• Solenoid valve for the automatic filling device defective
• Internal expansion vessel defective

Fill the heating installation. Check the product and the system for leakages. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check the cable for the pump/for the water pressure sensor. Check and, if required, replace the water pressure sensor. Check and, if required, replace the cable to the pump/to the water pressure sensor. Check the automatic filling device and replace it, if necessary. Check the internal expansion vessel and replace it, if necessary.

• Air in the product
• Fault in the electrical connection for the flow temperature sensor
• Fault in the electrical connection for the return temperature sensor
• Flow temperature sensor defective
• Return temperature sensor defective
• Pump blocked
• Pump runs with insufficient output
• 3-port diverter valve defective or blocked
• Internal expansion vessel defective

Purge the heating installation. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the flow temperature sensor. Check and, if required, replace the return temperature sensor. Check that the pump is working correctly. Check that the pump is working correctly. Check and, if required, replace the 3-port diverter valve. Check the internal expansion vessel and replace it, if necessary.

• Air in the product
• System pressure too low
• Fault in the electrical connection for the flow temperature sensor
• Flow temperature sensor defective
• Return temperature sensor defective
• Pump blocked
• Pump runs with insufficient output
• 3-port diverter valve defective or blocked
• Internal expansion vessel defective

Purge the heating installation. Check the system pressure. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the flow temperature sensor. Check and, if required, replace the return temperature sensor. Check that the pump is working correctly. Check that the pump is working correctly. Check and, if required, replace the 3-port diverter valve. Check the internal expansion vessel and replace it, if necessary.

• Wiring harness defective
• If present: Flue gas temperature monitor has triggered

Check the wiring harness including all plug connections and, if required, replace it (PCB plug X20, contact 14/15). Check and, if required, replace the flue gas temperature monitor.

• Gas solenoid valve not leak-tight
• PCB defective

Check that the gas valve assembly is working correctly and, if required, replace it. Replace the PCB.

• Hard ignition takes place
• Gas isolator cock closed
• Gas connection pressure too low
• Air in the gas supply (e.g. during initial start-up)
• Incorrect gas type set
• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Air intake pipe blocked
• Ignition failed
• Gas flow pressure too low
• Control electrode comes into contact with the burner
• Ignition electrode defective
• Burner defective
• Condensate pump (if fitted) defective
• Gas valve assembly defective/incorrect spare part gas valve assembly
• Interruption in the wiring harness
• Earthing defective
• Ionisation flow interrupted
• Fault in the flue gas route caused by recirculation or flue gas blockage
• Ignition transformer not connected
• Defective ignition transformer
• PCB defective
• Condensate in the combustion chamber due to a blocked condensate discharge

Check the heat exchanger, siphon, siphon adapter, siphon hose (connection between the primary heat exchanger and the siphon, and siphon hose outside of the product), flue pipe adapter, unit housing, front casing and side section for possible damage. If required, replace any damaged parts immediately. Open the gas isolator cock. Check the gas connection pressure. Reset the unit once. Check the gas type and the gas type setting under D.156 and D.157. Check the offset setting for the gas valve assembly. Check and, if required, replace the air intake pipe. Check the ignition using check programme P.021. Product starts: Ignition electrode, ignition transformer, gas valve assembly and fan are working, gas is flowing and the gas volume is correct, no blockage or recirculation detected. Product does not start and displays F.028 again: Carry out the next check for the cause. Check the gas flow pressure and the external gas pressure switch. Check the clearance between the control electrode and the burner. Check and, if required, replace the control electrode. Check and, if required, replace the ignition electrode. Check and, if required, replace the burner. Check and clean the condensate pump. Replace the condensate pump, if required. Check and, if required, replace the gas valve assembly. Check the wiring harness including all plug connections and, if required, replace it. Check the product's earthing. Check the control electrode, the connection cable and the plug connection. Check the entire flue gas route. Check the plug and the plug connection. Check that the ignition transformer is working correctly and, if required, replace it. Replace the PCB. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber.

• The gas supply is interrupted
• Fault in the flue gas route caused by recirculation or flue gas blockage
• Earthing defective
• Air intake pipe blocked
• Ignition misfire
• Condensate pump (if fitted) defective
• Control electrode comes into contact with the burner
• Burner defective
• Interruption in the wiring harness
• Ignition electrode defective
• Gas valve assembly defective/incorrect spare part gas valve assembly
• Condensate in the combustion chamber due to a blocked condensate discharge

Check the gas supply. Check the entire flue gas route. Check the product's earthing. Check and, if required, replace the air intake pipe. Check that the ignition transformer works correctly. Check and clean the condensate pump. Replace the condensate pump, if required. Check the clearance between the control electrode and the burner. Check and, if required, replace the control electrode. Check and, if required, replace the burner. Check the wiring harness including all plug connections and, if required, replace it. Check and, if required, replace the ignition electrode. Check and, if required, replace the gas valve assembly. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber.

• Fault in the electrical connection for the fan
• Fan blocked
• Fan defective
• Fault in the flue gas route caused by recirculation or flue gas blockage
• PCB defective

Check the wiring harness between the PCB and fan, including all plug connections. Check that the fan works correctly. Check and, if required, replace the fan. Check the entire flue gas route. Replace the PCB.

• Air/flue pipe blocked during initial start-up
• Air intake pipe blocked
• Gas flow pressure too low
• Fault in the flue gas route caused by recirculation or flue gas blockage
• Condensate in the combustion chamber due to a blocked condensate discharge
• Condensate pump (if fitted) defective
• Insufficient combustion air supply
• Control electrode defective
• Burner defective
• Gas valve assembly defective/incorrect spare part gas valve assembly

Check the entire flue gas route and deactivate D.145. Check and, if required, replace the air intake pipe. Check the gas flow pressure and the external gas pressure switch. Check the entire flue gas route. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber. Check and clean the condensate pump. Replace the condensate pump, if required. Check the combustion air supply. Check and, if required, replace the control electrode. Check and, if required, replace the burner. Check and, if required, replace the gas valve assembly.

• Fault in the flue gas route caused by recirculation or flue gas blockage
• Air intake pipe blocked
• Condensate in the combustion chamber due to a blocked condensate discharge
• Condensate pump (if fitted) defective
• Incorrect gas type set
• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Fault in the electrical connection for the gas valve assembly
• Gas valve assembly not electrically connected/incorrectly connected
• Control electrode defective
• Burner defective
• PCB defective
• Fan defective
• Air-mass flow sensor dirty or defective (only in conjunction with the conversion set comprising the air intake pipe with integrated non-return valve and air-mass flow sensor)

Check the entire flue gas route. Check and, if required, replace the air intake pipe. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber. Check and clean the condensate pump. Replace the condensate pump, if required. Check the gas type and the gas type setting under D.156 and D.157. Check the offset setting for the gas valve assembly. Check and, if required, replace the wiring harness for the gas valve assembly. Check the electrical connection to the gas valve assembly. Check and, if required, replace the control electrode. Check and, if required, replace the burner. Replace the PCB. Check and, if required, replace the fan. Check the air-mass flow sensor for dirt. If required, replace the entire air intake pipe.

• Interruption in the wiring harness to the gas valve assembly

Check the wiring harness between the PCB and gas valve assembly, including all plug connections (especially on the PCB).

• Interruption in the wiring harness
• Burner defective
• Gas valve assembly defective/incorrect spare part gas valve assembly
• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Control electrode defective
• Gas valve defective
• PCB defective
• Fault in the flue gas route caused by recirculation or flue gas blockage
• Air intake pipe blocked
• Condensate in the combustion chamber due to a blocked condensate discharge
• Condensate pump (if fitted) defective
• Gas flow pressure too low
• Incorrect gas type set

Check the wiring harness including all plug connections and, if required, replace it. Check and, if required, replace the burner. Check and, if required, replace the gas valve assembly. Check the offset setting for the gas valve assembly. Check and, if required, replace the control electrode. Replace the gas valve. Replace the PCB. Check the entire flue gas route. Check and, if required, replace the air intake pipe. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber. Check and clean the condensate pump. Replace the condensate pump, if required. Check the gas flow pressure and the external gas pressure switch. Check the gas type and the gas type setting under D.156 and D.157.

• Fault in the electronic connection for the cylinder outlet temperature sensor
• Cylinder outlet temperature sensor defective

Check the wiring harness between the PCB and sensor, including all plug connections. Replace the cylinder outlet temperature sensor.

• Short circuit in the eBUS connection
• Different polarities at the eBUS connection
• PCB defective

Check all eBUS connections. Check the polarity (±) of the eBUS connections. Replace the PCB.

• Limp home mode failed
• Fault in the flue gas route caused by recirculation or flue gas blockage
• Air intake pipe blocked
• Condensate in the combustion chamber due to a blocked condensate discharge
• Condensate pump (if fitted) defective
• Gas flow pressure too low
• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Interruption in the wiring harness
• PCB defective
• Fan defective
• Air-mass flow sensor dirty or defective (only in conjunction with the conversion set comprising the air intake pipe with integrated non-return valve and air-mass flow sensor)

Check the limp home mode and fault history, and carry out the required measures. Check the entire flue gas route. Check and, if required, replace the air intake pipe. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber. Check and clean the condensate pump. Replace the condensate pump, if required. Check the gas flow pressure and the external gas pressure switch. Check the offset setting for the gas valve assembly. Check the wiring harness including all plug connections and, if required, replace it. Replace the PCB. Use D.033 and D.034 to check whether the fan speed deviates by more than 20–30 rpm. Check the air-mass flow sensor for dirt. If required, replace the entire air intake pipe.

• Fault in the electrical connection for the gas valve assembly
• PCB defective

Check and, if required, replace the wiring harness for the gas valve assembly. Replace the PCB.

• Gas valve defective
• PCB defective
• Ignition electrode defective

Replace the gas valve. Replace the PCB. Check and, if required, replace the ignition electrode.

• PCB defective

Replace the PCB.

• Sensor defective
• PCB defective

Check the sensor displayed under D.166. If the displayed value for D.166 is > 20 and is not listed, replace the PCB.

• Electronics overheated
• PCB defective

Check the external heat effects on the electronics. Replace the PCB.

• Implausible flame signal
• PCB defective

Check the flame signal. Replace the PCB.

• PCB defective

Replace the PCB.

• Device Specific Number not set correctly following simultaneous replacement of the PCB and display
• Fault in the electrical connection for the gas valve assembly

Set the correct Device Specific Number. Following simultaneous replacement of the PCB and display, replace the control electrode. Check the wiring harness between the PCB and gas valve assembly, including all plug connections.

• Flow temperature sensor in the incorrect position
• Flow temperature sensor defective

Check the positioning of the flow temperature sensor. Check and, if required, replace the flow temperature sensor.

• Flow temperature sensor defective
• Fault in the electrical connection for the flow temperature sensor
• Return temperature sensor defective
• Fault in the electrical connection for the return temperature sensor

Check and, if required, replace the flow temperature sensor. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check and, if required, replace the return temperature sensor. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections.

• Fault in the electrical connection for the water pressure sensor
• Water pressure sensor defective

Check the wiring harness including all plug connections and, if required, replace it. Check and, if required, replace the water pressure sensor.

• Water pressure sensor defective
• Internal heating pump defective
• System pressure too low
• Internal expansion vessel defective
• Insufficient/no water in the product.
• Air in the product
• Open circuit in wiring harness (LIN cable)
• Interruption in the wiring harness

Check and, if required, replace the water pressure sensor. Replace the internal heating pump. Check the system pressure. Check the internal expansion vessel and replace it, if necessary. Fill the heating installation. Check the product and the system for leakages. Purge the heating installation. Check the wiring harness (LIN cable). Check the wiring harness including all plug connections and, if required, replace it.

• Interruption in the wiring harness

Check the wiring harness including all plug connections and, if required, replace it (PCB plug X20, contact 3/14).

• No feedback from the flue non-return flap or the feedback is incorrect
• Flue non-return flap defective
• Fault in the electrical connection to the condensate pump
• Condensate pump defective

Check that the flue non-return flap functions correctly. Replace the flue non-return flap. Check the electrical connection to the condensate pump. Replace the condensate pump.

• Incorrect control module connected
• Fault in the electrical connection for the domestic hot water connection temperature sensor

Check whether the control module is compatible with the product. For products without integrated domestic hot water generation: Check whether the bridge on plug X2 betwen contacts 2 and 5 is plugged in and is without interruption. If the bridge is working correctly, check and, if necessary, replace the wiring harness between the PCB and sensor.

• Inlet temperature sensor defective or not connected

Check and, if required, replace the NTC sensor, plug, wiring harness and the PCB.

• Interruption in the wiring harness
• Secondary heat exchanger clogged/blocked
• Pump non-return valve blocked
• Plug on domestic hot water connection temperature sensor loose/not plugged in
• Domestic hot water connection temperature sensor installed incorrectly
• Pump blocked
• The pump is defective.
• 3-port diverter valve defective or blocked
• Impeller sensor in the shift-load cylinder is defective

Check the wiring harness to the internal cylinder. Check the secondary heat exchanger for dirt. Check that the non-return valve for the pump in the internal cylinder is working correctly. Check the plug and the plug connection for the domestic hot water connection temperature sensor. Check whether the temperature sensor on the domestic hot water connection is correctly installed on the pipe. Check that the pump in the internal cylinder is working correctly. Replace the pump in the internal cylinder. Check and, if required, replace the 3-port diverter valve. Check and, if required, replace the impeller sensor in the shift-load cylinder.

• System pressure too low
• Flow temperature sensor: No contact
• Fault in the electrical connection for the flow temperature sensor
• Return temperature sensor: No contact
• Fault in the electrical connection for the return temperature sensor
• Insufficient/no water in the product.

Check the system pressure. Check whether the flow temperature sensor is lying against the flow pipe correctly. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Check whether the return temperature sensor is lying against the return pipe correctly. Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections. Fill the heating installation. Check the product and the system for leakages.

• Flow temperature sensor installed incorrectly
• Return temperature sensor installed incorrectly
• Flow and return temperature sensors inverted

Check whether the flow temperature sensor has been installed correctly. Check whether the return temperature sensor has been installed correctly. Check whether the flow and return temperature sensor has been installed correctly.

• Flow/return temperature sensors have been installed on the same pipe/wrong pipe

Check that the flow and return temperature sensors have been installed on the correct pipe.

• Fault in the electrical connection for the ignition transformer
• Defective ignition transformer

Check the wiring harness between the PCB and ignition transformer, including all plug connections. Check that the ignition transformer is working correctly and, if required, replace it.

• Gas valve assembly not connected
• Gas valve assembly connected incorrectly
• Short circuit in the wiring harness

Check the connection to the gas valve assembly. Check the connection to the gas valve assembly. Check the wiring harness and, if required, replace it.

• Incorrect pump connected

Check whether the pump that is connected is the one that is recommended for the product.

• Interruption in the wiring harness
• Plug on PCB loose/not plugged in

Check the wiring harness including all plug connections and, if required, replace it. Check the plug and the plug connection.

• Gas conversion in D.156 not completed

Check the setting in D.156.

• Fault in the flue gas route caused by recirculation or flue gas blockage
• Condensate in the combustion chamber due to a blocked condensate discharge
• Condensate pump (if fitted) defective
• Incorrect gas type set
• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Burner defective
• Gas valve assembly defective/incorrect spare part gas valve assembly
• Fault in the electrical connection for the gas valve assembly
• Control electrode defective
• PCB defective
• Air-mass flow sensor dirty or defective (only in conjunction with the conversion set comprising the air intake pipe with integrated non-return valve and air-mass flow sensor)

Check the entire flue gas route. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber. Check and clean the condensate pump. Replace the condensate pump, if required. Check the gas type and the gas type setting under D.156 and D.157. Check the offset setting for the gas valve assembly. Check and, if required, replace the burner. Check and, if required, replace the gas valve assembly. Check the wiring harness between the PCB and gas valve assembly, including all plug connections. Check and, if required, replace the control electrode. Replace the PCB. Check the air-mass flow sensor for dirt. If required, replace the entire air intake pipe.

• Gas connection pressure too low
• Fault in the flue gas route caused by recirculation or flue gas blockage
• Incorrect gas type set
• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Condensate in the combustion chamber due to a blocked condensate discharge
• Condensate pump (if fitted) defective
• Fault in the electrical connection for the gas valve assembly
• Control electrode defective
• Burner defective
• Gas valve assembly defective/incorrect spare part gas valve assembly
• PCB defective
• Air-mass flow sensor dirty or defective (only in conjunction with the conversion set comprising the air intake pipe with integrated non-return valve and air-mass flow sensor)

Check the gas connection pressure. Check the entire flue gas route. Check the gas type and the gas type setting under D.156 and D.157. Check the offset setting for the gas valve assembly. Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber. Check and clean the condensate pump. Replace the condensate pump, if required. Check the wiring harness between the PCB and gas valve assembly, including all plug connections. Check and, if required, replace the control electrode. Check and, if required, replace the burner. Check and, if required, replace the gas valve assembly. Replace the PCB. Check the air-mass flow sensor for dirt. If required, replace the entire air intake pipe.

• PCB self-test failed (PCB defective)

Replace the PCB.

• Gas valve assembly offset incorrectly stored in D.052 und ggf. D.182
• Fault in the electrical connection for the gas valve assembly

Check the offset setting for the gas valve assembly. Check the wiring harness between the PCB and gas valve assembly, incl. all plug connections.

• Power supply unit for the PCB is defective

Replace the PCB.

• Undervoltage in the power supply
• Pump defective
• Fault in the electrical connection for the pump

Check the mains voltage. If the mains voltage is not correct, contact the energy supply company. If the mains voltage is correct, replace the pump (voltage measurement via pump electronics). Check the wiring harness between the PCB and pump, including all plug connections.

• Overvoltage in the power supply
• Pump defective
• Fault in the electrical connection for the pump

If the mains voltage is not correct, contact the energy supply company. If the mains voltage is correct, replace the pump (voltage measurement via pump electronics). Check the wiring harness between the PCB and pump, including all plug connections.

• Fault in the electrical connection for the volume flow sensor in the domestic hot water circuit
• Volume flow sensor in the domestic hot water circuit defective

Check the wiring harness between the PCB and volume flow sensor, including all plug connections. Replace the volume flow sensor in the domestic hot water circuit.

• Fault in the electrical connection for the 3-port diverter valve
• 3-port diverter valve defective or blocked

Check the wiring harness between the PCB and 3-port diverter valve, including all plug connections. Check and, if required, replace the 3-port diverter valve.

• Dirt or foreign bodies in the pump

Clean the pump and, if required, replace the pump.

• The pump is defective.

Check and, if required, replace the pump.

• The pump temporarily reports excessive temperatures in the electronics

Check the pump and, if required, replace the pump.

• Air in the product
• Pump has been dry-running

Purge the heating installation. Replace the pump.

• The cable to the pump is defective
• The pump is defective.

Check the cable for the 230 V power supply to the pump and, if required, replace the cable for the 230 V power supply. Check and, if required, replace the pump.

• Pump blocked
• The pump is defective.

Check that the pump is working correctly. Check and, if required, replace the pump.

• 3-port diverter valve defective or blocked
• Plug on 3-port motorised valve loose/not plugged in
• Interruption in the wiring harness
• Domestic hot water circuit not connected
• External pump runs continuously
• The pump is defective.
• Cylinder bypass not connected

Check and, if required, replace the 3-port diverter valve. Check the plug and the plug connection on the 3-port motorised valve. Check the wiring harness including all plug connections and, if required, replace it. Connect the domestic hot water circuit. Check the external pump and the system configuration. Check and, if required, replace the pump. Check the cylinder connection pipes.

• Cylinder bypass not connected
• Domestic hot water circuit clogged/blocked

Check the cylinder connection pipes. Check the secondary heat exchanger for dirt.

• Fault in the electrical connection for the pump
• The pump is defective.

Check the wiring harness between the PCB and pump, including all plug connections. Check and, if required, replace the pump.

• Flue system configuration not completed

Check the flue gas configuration and complete this.

• Flue system configuration set incorrectly
• Incorrect gas type set

Set the approved flue system configuration. Check the gas type and the gas type setting under D.156 and D.157.

• The multiple-flue configuration conversion set is not suitable for the heat cell

Check and, if required, replace the conversion set comprising air intake pipe with integrated non-return valve and air-mass flow sensor.

• Multiple-flue configuration set incorrectly

Set the approved flue system configuration.

• Fan speed does not correspond to the target value
• Plug on PCB loose/not plugged in
• Interruption in the wiring harness
• Plug for air-mass flow sensor loose/not plugged in
• You exit the measuring range permanently. Air-mass flow sensor defective
• Flue gas pipe blocked

Use D.033 and D.034 to check whether the fan speed deviates by more than 20–30 rpm. Check the plug and the plug connection. Check the wiring harness including all plug connections and, if required, replace it. Check the plug and the plug connection for the air-mass flow sensor. Replace the entire air intake pipe. Check the entire flue gas pipe.

• Plug for air-mass flow sensor loose/not plugged in
• Plug on PCB loose/not plugged in
• Interruption in the wiring harness
• Measurement discrepancy too high. Air-mass flow sensor dirty.
• You exit the measuring range permanently. Air-mass flow sensor defective
• PCB defective

Check the plug and the plug connection for the air-mass flow sensor. Check the plug and the plug connection. Check the wiring harness including all plug connections and, if required, replace it. Check the air-mass flow sensor for dirt. Replace the entire air intake pipe. Replace the PCB.

• Transmission fault for calibration values

Replace the control electrode (D.146, D.147).

• Condensate in the combustion chamber due to a blocked condensate discharge

Check and, if required, clean the condensate discharge pipe including the siphon. Check the combustion chamber (electrodes, insulating mats, burner). If required, replace the insulating mats in the combustion chamber.

• Display electronics defective

Replace the display.

• Communication between the display and the PCB is interrupted

Check the connection between the display and the PCB. If required, replace the cable between the display and the PCB. If required, replace the display or the PCB.

• Overcurrent at the communication interface

Check the connection between the PCB and the modules that are connected to the interface. Check the connected modules and replace these, if required.