Probable errors, their codes and malfunctions of Buderus boilers

Probable errors and causes of occurrence

This article contains all possible malfunctions and options for eliminating them, as well as error codes for Buderus boilers.
All information is read in the following order: code - name - possible malfunction. If you have any additional questions, please leave them in the comments to this article. The content of the article

• Error code A - Chimney sweep mode
• Error code H - Heating mode
• Error code (=) H - DHW mode
• Error Code 0A - Blocked
• Error code 0A for GB072-24K
• Error code 0C - Burner
• Error Code 0E - On-Off Mode
• Error code 0H - Heat demand
• Error code 0L - Delay
• Error code 0U - Startup
• Error code 0Y - Temperature higher than set
• Error Code 2E - Bleeding Air
• Error code 2H - Pump protection
• Error code 2P - Temperature rise
• Error Code 5H - System Test
• Error Code H11 - Temperature Sensor
• Error code 0Y - Temperature at the flow sensor is more than 95 C
• Error Code 0Y - Hot Water Temperature Sensor High Temperature
• Error code 3A - Fan does not work
• Error code 3F - Interruption in operation
• Error Code 4C - Blocked
• Error Code 4U - Temperature Sensor
• Error Code 4Y - Temperature Sensor
• Error code 6A - No flame detected
• Error code 6L - No ionization signal during burner operation
• Error code 8Y - AT90 temperature control relay has tripped
• Error code 8Y - Temperature control relay AT90 faulty
• Error code 8Y - There is no jumper between the terminals of the separate AT90 temperature control relay
• Error code 8Y - Temperature control relay blocked
• Error code EL
• Error code 3C - Fan operation error
• Error Code 3L - Fan turned off during delay time
• Error Code 3P - Fan is too slow
• Error code 3Y - Fan running too fast
• Error code 4C - Temperature limiter
• Error Code 4U - Temperature Sensor
• Error code 4Y - Flow temperature sensor faulty (open)
• Error Code 6A - Error: Flame Not Found
• Error code 6C - In shutdown mode, the boiler registers a flame
• Error Code 6C - Flame detected after gas supply is turned off
• Error code 7L - Timing error at first delay time
• Error code 7L - Timing error when trying to restart
• Error code 9L - Gas fittings faulty
• Error code 9P - KIM not recognized
• Error code EL - KIM or main regulator BC20 is faulty
• Error codes for gas wall-mounted boilers Buderus Logamax
• Error code 1A - Exhaust gas outlet at flow fuse
• Error code 1L - Exhaust gas outlet on the combustion chamber
• Error code 1Y - Exhaust gas temperature sensor not detected
• Error code 2E - Insufficient filling pressure of the heating system
• Error code 2P - Temperature difference too large
• Error code 4C - Flow limiter has tripped
• Error code 4E - Burner chamber temperature sensor not detected
• Error code 4Y - Flow temperature sensor does not work
• Error code 5H - EMS communication interrupted
• Error Code 6A - No Flame Detected
• Error Code 6C - Flame detected after gas supply is turned off
• Error code 8Y - Jumper not detected on ST8 161
• Error code 9C - Coding plug not detected
• Error code CL - Hot water temperature sensor is faulty
• CP Error Code - Boiler Sensor Not Detected
• EC Error Code - Internal Fault
• Error Code EL - Invalid Reference Voltage
• Error code EP - By mistake, the fault message reset button was pressed for too long (more than 30 seconds)
• Malfunctions of Buderus boilers
• The burner does not turn on
• The burner starts and switches to fault. No spark when igniting
• Burner starts and switches to fault
• The Buderus boiler burner starts and switches to fault. No ionization current
• The burner starts and switches to fault. Ionization current less than 1.5 mA
• Boiling sounds

Error code A - Chimney sweep mode

The device is in “chimney sweep” mode. After 15 minutes, the chimney sweep mode is automatically deactivated.

Error code H - Heating mode

The Buderus boiler is in heating mode.

Error code (=) H - DHW mode

The device is in DHW mode.

Error Code 0A - Blocked

The clock interlock is active: the delay time between turning off and turning on the burner has not yet expired (service function 2.3b).

Error code 0A for GB072-24K

Duration of hot water support: the time interval of hot water support has not yet been exhausted (service function 2.3F).

Error code 0C - Burner

The burner turns on.

Error Code 0E - On-Off Mode

Heat demand is less than the minimum heating capacity of the boiler. The boiler operates in on-off mode.

Error code 0H - Heat demand

The device is in a ready state, there is no need for heat.

Error code 0L - Delay

The gas valve opens, the first delay time.

Error code 0U - Startup

The boiler starts.

Error code 0Y - Temperature higher than set

The actual flow temperature is higher than the set temperature. The boiler turns off.

Error Code 2E - Bleeding Air

Error: The bleed function is active.

Error code 2H - Pump protection

The protection against jamming of the heating circuit pump and the three-way valve is active.

Error code 2P - Temperature rise

Limitation of gradients: temperature rises too quickly in hot water mode.

1. Check the operating pressure in the heating system.
2. Open the service valves.
3. Make the electrical connection of the heating circuit pump to the BC20 main controller.
4. Check or replace the heating circuit pump.
5. Correctly set the pump power or its characteristic and match it to the maximum power.

Error Code 5H - System Test

Boiler control system test.

Error Code H11 - Temperature Sensor

Damage to the DHW temperature sensor (GB072-24K).

1. Remove the temperature sensor.
2. Check it and if it is faulty, replace it.
3. Check the connecting cable for breaks and short circuits, replace if damaged.

Error code 0Y - Temperature at the flow sensor is more than 95 C

This message may appear in the absence of a fault, if all valves on the radiators suddenly close or after drawing hot water from the GB072-24K.

1. Check the operating pressure in the heating system.
2. Open the service valves.
3. Make the electrical connection of the heating circuit pump to the BC20 main controller.
4. Check or replace the heating circuit pump.
5. Correctly set the pump power or its characteristic and match it to the maximum power.
6. Check for damage or short circuit of the flow temperature sensor and its wire, replace if necessary.

Error Code 0Y - Hot Water Temperature Sensor High Temperature

1. Check the correct position of the sensor.
2. Check it and if it is faulty, replace it.
3. Insert KIM correctly, replace if necessary.

Error code 3A - Fan does not work

Check it and if it is faulty, replace it.

Error code 3F - Interruption in operation

The burner and fan have been running for 24 hours without interruption and are switched off for a short time for safety reasons.

Error Code 4C - Blocked

The heat exchanger temperature limiter or the flue gas temperature limiter of the Buderus boiler has tripped. If a blocking fault exists for a long time, it becomes a blocking fault.

Error Code 4U - Temperature Sensor

Flow temperature sensor faulty (short circuit). If the fault exists for a long time, the display will show fault code 4U and operating code 222.

Error Code 4Y - Temperature Sensor

The flow temperature sensor is faulty (break). If the fault persists for a long time, the display will show fault code 4Y and operating code 223.

Error code 6A - No flame detected

After the 4th ignition attempt, the blocking fault becomes a locking fault.

Error code 6L - No ionization signal during burner operation

The burner restarts. If ignition is unsuccessful, blocking error 6A will be displayed; after the 4th ignition attempt, the blocking error becomes a failure.

Error code 8Y - AT90 temperature control relay has tripped

1. Check the AT90 temperature control relay adjustment.
2. Check the heating control setting.

Error code 8Y - Temperature control relay AT90 faulty

Check for damage or short circuit to the temperature sensor and its wire, replace if necessary.

Error code 8Y - There is no jumper between the terminals of the separate AT90 temperature control relay

If a temperature control relay is not connected, install a jumper.

Error code 8Y - Temperature control relay blocked

1. Unlock the temperature control relay.
2. Check condensate drainage.
3. The condensate pump does not work - replace the condensate pump.

Error code EL

The main regulator BC20 is faulty - replace it.

Error code 3C - Fan operation error

Check the fan and its wire with plug, replace if necessary.

Error Code 3L - Fan turned off during delay time

Check and, if necessary, replace.

Error Code 3P - Fan is too slow

Check and, if necessary, replace.

Error code 3Y - Fan running too fast

1. Check and, if necessary, replace.
2. Check the flue gas system and clean or repair if necessary.

Error code 4C - Temperature limiter

Error in heat exchanger temperature limiter or flue gas temperature limiter.

1. Check: for damage to the heat exchanger/flue gas temperature limiter and its connecting wire, replace if necessary, operating pressure in the heating system, temperature limiter, replace if necessary, pump pressure, replace the pump if necessary, fuse, replace if necessary.
2. Remove air from the boiler.
3. Check the water circuit of the heat exchanger, replace if necessary.
4. For Buderus boilers with a divider in the heat exchanger, check whether the divider is installed.

Error Code 4U - Temperature Sensor

Flow temperature sensor faulty (short circuit).

Check for damage or short circuit to the temperature sensor and its wire, replace if necessary.

Error code 4Y - Flow temperature sensor faulty (open)

Check for damage or breakage of the temperature sensor and its wire, replace if necessary.

Error Code 6A - Error: Flame Not Found

1. Check: protective conductor connection, whether the gas valve is open, gas supply pressure, electrical connection, electrodes with wires, flue gas exhaust system, clean or repair if necessary.
2. Check the gas-air ratio, correct if necessary.
3. For natural gas: check the gas flow control relay, replace if necessary.
4. When working with combustion air taken from the room, check the air supply to the room and the ventilation openings.
5. Clean the condensate siphon drain.
6. Remove the membrane in the fan mixing device and check for cracks and dirt on it.
7. Clean the heat exchanger of the Buderus boiler.
8. Check the gas fittings, replace if necessary.
9. Insert KIM correctly, replace if necessary.
10. Two-phase network (IT): install a resistance of 2 ohms between PE and N at the connection of the electronic board to the mains.

Error code 6C - In shutdown mode, the boiler registers a flame

1. Check the electrodes for contamination and replace if necessary.
2. Check the flue gas system and clean or repair if necessary.
3. Check the humidity of the electronic board, dry if necessary.

Error Code 6C - Flame detected after gas supply is turned off

1. Check the gas fittings, replace if necessary.
2. Clean the condensate siphon.
3. Check the electrodes and connecting wires and replace if necessary.
4. Check the flue gas system and clean or repair if necessary.

Error code 7L - Timing error at first delay time

Replace the BC20 main regulator.

Error code 7L - Timing error when trying to restart

Replace the BC20 main regulator.

Error code 9L - Gas fittings faulty

The coil or connecting wire of the gas fitting is faulty.

1. Check the wires, replace if necessary.
2. Replace gas fittings.

Error code 9P - KIM not recognized

Insert KIM correctly, replace if necessary.

Error code EL - KIM or main regulator BC20 is faulty

Replace KIM. Replace the BC20 main regulator.

Boiler errors Buderus Leave

Training of service specialists for repair and maintenance of Buderus boilers

German heating technology – time-proven quality, reliability, efficiency. But provided that the manufacturer’s recommendations in terms of installation and operation of the equipment are strictly followed.

Not all owners of Buderus boilers are guided by this or are not able to fulfill certain conditions, and therefore face problems expressed in the incorrect functioning of the heating unit or its stopping due to an emergency signal. Errors that appear on the display tell you what the reason is.

The article will help users correctly decipher the symbolism and provide useful recommendations for restoring Buderus functionality.

On a note! Buderus Logamax wall-mounted boilers with one or two circuits are the most purchased. They are available in several versions (U042–072), but the errors of each are identical. You can rely on the recommendations given in the article when troubleshooting, solving problems with the functioning of other Buderus models (Logamax plus, Logano).

• Control panel Buderus Logamax U042
• Boiler control panel Buderus Logamax plus B172
• Buderus Logano boiler control panel
• Control panel Buderus Logamax U072

Errors on the boiler display

Boiler display Buderus U072

The search for any malfunction of the heating unit begins with checking the network voltage - this is an immutable truth. Only after making sure that there is no “drawdown”, the nominal value corresponds to ~220±10 V, can you proceed to analyzing the code and identifying the problem that has arisen with Buderus.

2E (4C)

The reasons that cause these codes to appear are largely the same. Errors indicate insufficient pressure in the circuit (below critical) or overheating of the boiler. For example, in the instructions for the Buderus Logamax version U042, the 4C symbolism is interpreted exactly this way: a sharp increase in the water temperature in the heating system. This is due to a decrease in its volume or slow circulation.

What to do

1. Add liquid. The normal pressure is 1.5–2.5 bar (controlled by a pressure gauge on the front panel). The repeated display of error 2E (4C) some time after starting the boiler indicates a malfunction of the Buderus pump or a defect in the circuit.

2. Make sure there are no leaks. Loose pipe connections, a split seam in a heating radiator, cracks in the expansion tank or boiler heat exchanger - it’s not difficult to find the problem area by looking at the puddles.

3. Vent the air. His “bubble” blocks the fluid movement channel and causes the Buderus error. Automatic valves may fail (the air removal paths are clogged, the spring is weakened), so you should not rely on them. You need to walk around the house and check by touch the degree of heating of the batteries: the simplest method for calculating the location of the air lock.

4. Check the functionality of the Buderus boiler pump. A decrease in pressure is caused by its stopping or slow rotation of the impeller.

• Check supply voltage. It may not be supplied to the winding due to a short circuit or broken wires, oxidation of contacts, or poor fit of the plug in the socket.
• Partially disassemble the pump. If in a system with Buderus the coolant is of poor quality, increased hardness, salt deposits on the blades and shaft are inevitable. This results in incorrect operation of the device and overheating of the boiler. The error can be eliminated by cleaning and rinsing the defective areas.

5. Check the signal circuit of the temperature sensor at the Buderus output. A short circuit in it is one of the causes of the overheating error.

Recommendation : if there is a malfunction in the sensor itself, code 4Y is displayed.

6. If monitoring the condition of the heating system and Buderus did not give results, one thing remains - the primary heat exchanger of the boiler. Over time, deposits form in its cavity, and the diameter of the internal channel decreases: the speed of water circulation gradually decreases and at some point an error appears.

Recommendation : cleaning the heat exchanger yourself will be free. But what will be the effect? In practice, after such maintenance, Buderus does not work for a long time and stops again due to the same error. If it was not possible to prepare the heat exchanger in the off-season, you need to remove it and take it to a service center. In 2-3 days it will be ready, and there will be no problems with the boiler until spring.

All advice on servicing the device on site (there is plenty of it on the Internet) is given, judging by the content, by people with little knowledge. For high-quality cleaning, a special reagent (deposit softener) is poured into the cavity, and rinsing after exposure is carried out under pressure. This is the only way to remove all oxides and build-ups from a channel of complex configuration.

3A

Reduced rotation speed of the boiler fan blades. The main reason is an underrated supply voltage or an open circuit. In the latter case, the speed drops sharply and is maintained only by traction. The Buderus automation system detects this and issues an error.

Recommendation : if there is no obvious reason, change the fan. Checking the continuity of the motor winding will not give a complete picture - an interturn short circuit is possible. In the Buderus boiler series U072, its malfunction is indicated by code C7.

3C (3Y)

Problem with the pressure switch: it is faulty (does not respond to closing/opening contacts). The second reason is that the chimney is clogged.

Recommendation : if cleaning the gas removal channel does not eliminate the error, and the fan is working normally, you need to change the differential relay.

6A

An error indicating a lack of flame in the boiler chamber.

Check what

• Position of shut-off valves on the pipe. In private buildings, a shut-off valve (element of the safety group) is installed on it. Sometimes it is triggered by power surges, and you need to cock it manually.

Burner flame of the Buderus u072 boiler

• Gas pressure. You don’t need a special device for this: just light the stove burner and look at the flames. If they are smaller than usual, the cause of the Buderus error has been found.

Recommendation : with an autonomous gas supply, you need to check the reducer.

This is especially true when the cylinder group is located in an insufficiently insulated outdoor closet - there is a high probability of icing.

• Ionization sensor status. The Buderus boiler error appears when it is dirty. Eliminated by cleaning the electrode.

The reason for the lack of flame may be the gas fittings of the boiler. This is evidenced by the error d7 of some versions of Buderus. Only a specialist can carry out an accurate diagnosis. There is no point in changing it yourself - you will also need to correctly adjust the pressure.

CL (CP)

The error indicates the absence of a signal from the temperature sensor of the DHW system (for single-circuit boilers - boiler).

Fd

The code is displayed when the rules for using Buderus are violated - the start button is held down for no more than 30 seconds.

Recommendation : Try again and the error will disappear.

Problems not shown on the display

When they occur, the Buderus error is not displayed, but a number of signs indicate incorrect operation of the boiler or the entire heating system.

Adjusting the circulation pump

1. Slow heating of batteries; noise of fluid circulating along the circuit. The main reason is the incorrectly set pump speed. The switch is located on its body.

2. “Difficult” ignition, boiler efficiency is lower than declared. There are several options: from poor burner performance to the use of gas with characteristics that do not meet the manufacturer’s requirements.

Recommendation : carry out Buderus service, check the set parameters.

The article provides explanations for all problems that can be resolved independently. It’s better not to go deeper - the boiler is expensive, and unprofessional intervention in its operation will not lead to anything good.

Useful tips

Checking all electrical circuits

• Errors that appear on the Buderus display are generated in the electronic board of the boiler based on signals received from the corresponding sensors. The first step in solving any problem should be to check all electrical circuits. Loose contacts, oxidized lamellas - this can be eliminated in a few minutes. It will not take much more time to replace the wire in case of insulation melting or breakage.

• Instability in the power supply often triggers Buderus errors. This often manifests itself at sites in intensively built-up areas. Periodic switching on of welding machines and powerful heaters leads to voltage surges and phase imbalance. The conclusion is simple: before searching for the cause of the boiler error display, you need to check the parameters of the supply network.

• Uninterrupted operation of Buderus is ensured by its connection via a UPS. The stabilizer will not give the desired effect, especially since it is provided for in the electronic circuit of the boiler. The power supply supplies voltage even if there are problems with power lines due to the built-in batteries; depending on their total capacity from 2 to 14 hours. For suburban properties this is a more than rational solution.

• Not everyone carefully reads the manufacturer's obligations. One of the guarantee conditions for Buderus is professional installation. The absence of a service organization mark in the boiler passport is the reason for refusal in case of user complaints. In order not to pay for warranty service or repair of heating equipment out of your own pocket, it is better not to do independent installation and piping (in order to save money) with Buderus.

Error codes for gas wall-mounted boilers Buderus Logamax

Error code 1A - Exhaust gas outlet at flow fuse

Check the gas exhaust path.

Error code 1L - Exhaust gas outlet on the combustion chamber

Check the heat exchanger for contamination.

Error code 1Y - Exhaust gas temperature sensor not detected

Check the flue gas temperature sensor and connecting cable for damage.

Error code 2E - Insufficient filling pressure of the heating system

Check the filling pressure and increase it if necessary.

Error code 2P - Temperature difference too large

Check the pump and bypass line.

Error code 4C - Flow limiter has tripped

Check the pressure in the system, temperature sensors, check the operation of the pumps and the fuse on the printed circuit board, remove air from the device.

Error code 4E - Burner chamber temperature sensor not detected

Check the temperature sensor in the burner chamber and the connecting cable for damage.

Error code 4Y - Flow temperature sensor does not work

Check temperature sensor and connecting cable.

Error code 5H - EMS communication interrupted

Check connecting cable and regulators.

Error Code 6A - No Flame Detected

Is the gas valve open? Check the pressure in the gas network, the network connection, the starting electrode with cable and the ionizing electrode with cable.

Error Code 6C - Flame detected after gas supply is turned off

Check the ionizing electrode. Check gas fittings.

Error code 8Y - Jumper not detected on ST8 161

If there is a jumper, insert the plug correctly and check the external limiter. Otherwise: is there a jumper?

Error code 9C - Coding plug not detected

Insert the coding plug correctly, measure it and replace it if necessary.

Error code CL - Hot water temperature sensor is faulty

Logamax U054-24K

• Check the temperature sensor and connecting cable for damage or short circuit;
• The hot water temperature sensor is not installed correctly.

Logamax U054-24K

• Check the installation area, if necessary, remove the sensor and reinstall it using heat-conducting paste.

CP Error Code - Boiler Sensor Not Detected

Check the boiler sensor and connecting cable.

EC Error Code - Internal Fault

Check the connection of the electrical plug contacts and start lines and, if necessary, replace the printed circuit board.

Error Code EL - Invalid Reference Voltage

Replace the printed circuit board.

Error code EP - By mistake, the fault message reset button was pressed for too long (more than 30 seconds)

1. Press the reset button again and hold it down for less than 30 seconds.
2. The outside temperature sensor is not detected. Check the outside temperature sensor and connecting cable for damage.

Buderus boiler error 6a

05.11.2017

Buderus has been part of the Bosch group since 2003. Wall-mounted boilers of this brand are represented by three model series Logamax U072, Logamax U052 and Logamax U044.

The company provides a wide range of boilers with various technical equipment.

The series and model of the boiler is usually indicated on a special plate, which is located on the boiler. For example, Logamax U072 - 24K means:

U – gas heater with circulation pump

0 – gas burner with pre-mixing

7 – boiler series

2 – type of combustion chamber (2 – closed, 4 – open)

24 – boiler rated power

K – two-circuit model

If problems arise, this information will be useful in diagnosing the nature of the problem.

The seventh series of Logamax U072 boilers is represented by the widest model range in the power range from 12 to 35 kilowatts. Boilers of this series are widely used for apartment heating and heating of small private houses.

Distinctive features:

• low noise level - boilers operate very quietly indeed
• variable speed fan
• stylish design and convenient controls

A boiler with modern technical equipment, compact dimensions and an affordable price.

Buderus boiler malfunction

Like any other wall-mounted boiler, Buderus is equipped with a protection system and if an emergency occurs, the operation will be stopped and the user will receive an error message indicating in which system of the unit the malfunction occurred.

Some devices are equipped with an LCD display, and the user will see an error code. If the boiler is not equipped with a display, the fault will be indicated by flashing temperature indicators. For example, if the temperature indicator flashes 80, this means a 3C error, which would appear on a similar boiler with a display.

A complete list of error codes reflected by blinking indicators can be seen in the figure. Next, we will consider the most popular errors and recommendations for eliminating them.

Buderus boiler error 6a

Error buderus 6a (second indicator flashes) occurs when the boiler does not detect a flame on the burner. Flame control is one of the most important functions of a safety system. To control the flame, there is a special electrode on the burner through which a small current flows during combustion. The control board constantly records this current. If for some reason the current at the ionization electrode disappears, error 6a occurs. The same thing will happen, for example, after several unsuccessful attempts to ignite the boiler - this is the most common situation.

The reasons are standard for all boilers:

• incorrect adjustment of the gas valve (insufficient supply gas pressure)
• poor contact or lack of signal from the flame ionization sensor
• malfunction of the flame control sensor (contamination, breakdown)
• failure of the control board (repair of the boiler control board is required)
• incorrect electrical connection of the boiler (lack of grounding)
• lack of air for proper combustion (lack of draft, clogged inlet pipe)

Error buderus 6a is classified as critical, which means that after such a malfunction occurs, the boiler will not start on its own - the error must be reset!

There are two options to reset the error:

• keep the OK button pressed until the fault signs disappear, the boiler starts working again and the display shows the flow temperature.
• Turn the boiler power on and off

Buderus boiler error 6a how to fix

First of all, you need to exclude the accidental occurrence of an error and simply reset it. If the error occurs again and the boiler does not start, then the problem requires a solution. In most cases, ignition problems can only be corrected by a qualified specialist. The simplest thing that can be done is to inspect the combustion chamber and electrodes for contamination and clean if necessary.

If the boiler makes unsuccessful attempts to ignite, visually check that the spark is striking the burner and not somewhere else. If you hear a crackling sound, but there is no spark between the electrode and the burner, the insulation of the electrode is probably damaged somewhere and needs to be replaced.

The gas valve can only be adjusted by a specialist. Checking the presence of proper network gas pressure can be done through a gas stove. If you light all the burners on the stove at the same time, they should work without interruption. If this is not the case, we can assume that the incoming pressure is not enough and you need to call the gas service.

In our practice, there was a case when a crack in the combustion chamber inspection window was the cause of a malfunction.

If the boiler lights up, but goes out after a while, this may be due to a faulty electronic board. You can check by replacing the board with a known good one.

Buderus error 3c (fourth indicator 80 flashes)

If such an error occurs, the boiler control board does not receive a signal from the differential pressure switch, that is, its contacts do not close after the fan starts. The pressure switch is used to determine the necessary conditions for removing combustion products.

The procedure for putting the boiler into operation is as follows:

1. The control unit gives a signal to start the fan
2. The fan creates the necessary vacuum in the exhaust pipe
3. The differential relay registers the vacuum and the microswitch contacts close
4. The board sends a signal to open the gas valve and ignite

Therefore, to understand the problem, you need to determine at what specific moment the boiler goes into error. If the fan starts, but the relay does not click, it is tedious to inspect the supply pipes; perhaps there is a blockage or condensation, or there is actually a blockage in the chimney itself.

If the fan does not start, you need to check whether voltage is supplied to it. A faulty electronic board may be the reason why the fan does not start.

If the fan is working, there are no problems with the chimney and the pneumatic relay tubes, you need to check the pneumatic relay itself, creating a vacuum yourself and checking for a characteristic click.

Constantly closed relay contacts or their opening during burner operation will also be regarded by the security system as a malfunction.

Buderus boilers can be equipped with a fan with adjustable rotation speed, which is controlled electronically and equipped with a sensor.

Error 4C (first indicator blinks)

The error occurs either when there is insufficient pressure in the heating system, or when the temperature at the outlet of the primary heat exchanger is too high. You need to check the pressure gauge reading. If the pressure in the system is insufficient - less than 0.5 bar, it is necessary to recharge the boiler. Too high a temperature on the heat exchanger can also be caused by problems with coolant circulation or air lock. The source of the error is either a hydraulic pressure switch or a boiler water temperature limiter - a thermostat, which is located immediately at the outlet of the heat exchanger.

Error 4Y (first two lights flash)

The flow temperature sensor is faulty. For diagnostics, you need to measure the resistance at the sensor contacts. At room temperature it should be within 10 kOhm, the sensor connection must be reliable, because in case of a break there will also be an error. The logic of the CL error is the same, only for the DHW temperature sensor. If the temperature sensor malfunctions, the boiler operation is blocked, only the circulation pump remains running to prevent freezing. If the DHW temperature sensor is damaged, the boiler operation will not be blocked.

Error 2E (the first three indicators blink)

The logic of the error is that the supply temperature rises too quickly, i.e. The coolant at the outlet of the heat exchanger heats up too quickly and to prevent emergency overheating, the operation of the boiler is blocked for two minutes. The main reason for this behavior of the boiler may be poor coolant circulation. Poor circulation can most often be caused by:

• circulation pump malfunction or insufficient performance
• heat exchanger clogged with dirt or scale
• air in the heating system

Malfunctions of Buderus boilers

If you are not 100% sure what exactly the problem is and that you can solve it, immediately contact the service center to diagnose and fix the problem.

The burner does not turn on

The emergency switch for the heating system is in the off position - on.

Control system start switch in off position - turn on.

The circuit breakers are faulty - check their functionality and, if necessary, replace the defective circuit breaker.

The boiler water temperature regulator is damaged - check and, if necessary, replace defective parts.

The safety temperature limiter is damaged - check and, if necessary, replace defective parts.

Error message from external safety devices (for example, from a water level safety device) - the consumer must check the Buderus boiler, eliminate the fault and, if necessary, replace the element.

The flue gas monitoring system has activated:

• AW 10 - unlock the flue gas control system;
• AW 50 - Wait a maximum of 15 minutes.

The boiler will turn on automatically if there is a request for heat. If it is triggered multiple times, check the flue gas path and check the functionality of the flue gas control system. If there is a defect, replace it.

The burner starts and switches to fault. No spark when igniting

Is there a sound when an ignition spark forms when the ignition cable is removed?

• If not, then replace the ignition transformer;
• If yes, then replace the ignition electrode or ignition burner.

Burner starts and switches to fault

All gas shut-off valves are closed - open the gas shut-off valves.

Natural gas supply pressure is more than 8 mbar - if not, determine the cause and correct the problem.

Has air been removed from the gas pipeline? Remove air until gas can be ignited.

The Buderus boiler burner starts and switches to fault. No ionization current

If connections N and L are mixed up, eliminate the error.

Is there voltage between L and PE? If not, ground the PE, in this case install an isolation transformer.

Poor contact of the ionization wire - eliminate the error, in this case, replace the defective part.

Short to ground on the ionization electrode - correct the damage.

Burner control defective - replace element.

The burner starts and switches to fault. Ionization current less than 1.5 mA

The core or ceramics of the ionization electrode is dirty - clean the ionization electrode and, if necessary, replace the ignition burner.