Viessmann gas boiler error codes: how to determine the malfunction and carry out the repair correctly

Autonomous heating has a number of significant advantages over centralized heating. These are affordable prices, economy and high efficiency. To organize an independent heating system, you need a boiler that can not only work perfectly, but also not create problems.

Eliminate problems with models of the new generation with intelligent control devices and multi-layered protection. For example, the Viessmann gas boiler will “prompt” errors itself. The smart unit will display on the display an alphanumeric code of an impending malfunction and a breakdown that has already occurred.

We will tell you how to use the code to determine in which of the units or systems of the unit there was a violation. We will show you how to find the problem and correct the situation in a timely manner in order to prevent a more serious problem. The owner of the unit will only have to decide whether he himself will repair or call a master.

Error codes for Vitopend 100-W boilers

The electronic system of the units is configured in such a way that in the event of malfunctions of Viessmann gas boilers, the breakdown is automatically detected. In this case, the error code is displayed on the device display. This makes it possible not to disassemble the entire boiler, but to pinpoint the performance of a specific part.

The explanation of the symbols is given in the detailed instructions for licensed electricians and gas workers accredited to perform repair of gas boilers of this German brand by the manufacturer.

These boilers are produced in single-circuit and combined ones. They can operate both on natural gas and on reduced gas. They have a closed combustion chamber. The power range is from 10 kW to 34 kW. A modulating burner with a built-in fan makes it possible to efficiently remove the products of processing of gaseous fuel from the combustion chamber of the boiler.

The standard value of the efficiency of this boiler model is 85%. The controller with the integrated diagnostics system is built into a single module with the unit. The Viessmann gas boiler of the Vitopend 100-W series issues typical error codes on a digital display with white backlighting.

Fault code: 06

When this error code appears, the boiler burner is blocked. This is due to too low pressure of the heating water circulating through the heat exchanger for the heating circuit. At the inlet to the diaphragm tank, the pressure must be at least 0.8 bar.

To solve the problem, you need to check the pressure in the unit, remove excess air from the radiators and replenish the coolant volume through the make-up valve located at the bottom of the case.

According to the instructions, fresh water must be poured into the installation from a centralized water supply system or an individual source. If the water hardness exceeds the manufacturer's recommended limit of 4.5 mg-eq / l (milligram-equivalent per liter), then it is necessary to provide for the installation of a filter device.

The pH value of water, which can be prepared by a German-made boiler, should be in the range from 6.5 to 8.5. The manufacturer allows the addition of antifreeze to the water.

The pressure test is carried out in a cold installation at a system temperature of less than 30 ° C. The minimum inlet pressure to the diaphragm expansion vessel must be 0.8 bar or 0.08 MPa. The maximum working pressure of the coolant running through the boiler should be 3 bar or 0.3 MPa.

The expansion tank is checked as follows. The water from the installation is drained until the pressure in the boiler pressure gauge is 0 bar. If the static pressure of the system is higher than the pressure in the expansion vessel, then nitrogen must be injected through the nipple up to a value of 0.1 - 0.2 bar higher than the static pressure.

Fault code: 0A

The appearance of the 0A error on the display is accompanied by the burner blocking, and the reason for its occurrence is a low value of the dynamic gas pressure. According to the instructions, the value of the dynamic pressure of natural gas should be in the range from 8 to 25 mbar, and the pressure of the reduced gas - from 27.7 to 57.5 mbar.

The system pressure is checked using a gas pressure gauge with a scale division of 0.1 mbar. If a low pressure is detected in the gas pipes, then it is necessary to contact the organization supplying the gas in order to find out the reasons.

If the pressure value corresponds to the indicator specified by the manufacturer, then it is necessary to start checking the operability of the pressure control relay built into the boiler. If a breakdown of the relay is detected, then it is advisable to contact the service center.

You can buy a gas pressure monitor for this boiler model from the official supplier of Viessmann parts. However, repair, installation and replacement must be carried out by certified craftsmen who have passed certification and received permission from the manufacturer to repair boilers of this brand.

Fault code: 0C

This error code appears on the display if the mains voltage has dropped significantly. In this case, the burner is blocked, and in order to solve the problem, it is necessary to check the mains voltage and find out the reason for its drop. The network may sink if several electrical appliances are connected at the same time.

Sometimes the voltage drop is associated with a breakdown of the contact connection at the junction of the internal wiring. The problem of a lack of mains voltage can also arise when selecting a cable with an insufficient cross-section. The owner himself must solve these problems.

A situation of seasonal decrease in voltage often arises. When many users turn on the heating equipment at the same time, and the voltage in the distribution network is not enough to meet the increased consumption. In such cases, it is necessary to contact the organization that provides the power supply.

Problems with a voltage drop in the mains supplying volatile devices of Wisman boilers are solved by installing stabilizer for gas boiler.

Fault code: CC

The CC error indicates a malfunction in the operation of the external expansion module. This error message is caused by the loss of communication between the external expansion module and the device controller. Most often, a banal check of the cable connecting these parts allows you to eliminate the malfunction.

If the contact has gone away, then the cable just needs to be connected. If the cable is broken or broken, then it must be replaced.

Fault code: F02

The appearance of the F02 code on the display indicates a burner malfunction. This alphanumeric designation appears when the temperature limiter is triggered. First of all, the user should check the filling of the system with the coolant and release excess air from the circulation pump and radiators.

If, after carrying out these procedures, the error continues to be displayed, then you need to check the temperature limiter for a malfunction. It is also necessary to check the connecting cables.

The limiter is checked as follows:

• The sensor cables are disconnected;
• It is determined whether the current flows through the temperature limiter (this is done by a universal measuring device);
• The defective limiter should be removed;
• The installation site is lubricated with heat-conducting paste;
• A new limiter is installed;
• Unlocking is carried out by pressing the MODE and OK buttons until the reset symbol flashes on the display;
• Re-ignition is performed.

The temperature limiter is checked to make sure that after an emergency shutdown the gas control box does not unblock when the boiler water temperature is below 90 ° C.

Fault code: F03

Code F03 indicates that the flame signal appears before the burner starts. Repair of Wisman gas boilers that issue this error consists in checking and repairing the ionization electrode.

Additionally, check the connecting cables. It is necessary to turn off and restart the mains switch. You can also follow the above reset procedure.

Fault code: F04

This error indicates the absence of a flame signal. In most cases, the problem is solved after restarting the boiler or carrying out a reset. If this method does not help, then you need to check the condition of the two ignition electrodes. Then the ionization electrode is checked. Perhaps they have mechanical damage or have changed their position relative to each other.

Then you should check the connecting cables. If during inspection breakdowns are revealed, then these parts must be replaced with new ones or repaired. Dismantling of broken products and installation of new ones must be carried out strictly according to the instructions.

In addition to faults with ignition, there may be problems with the gas supply. It is necessary to check the gas pressure, inspect the gas control valve. Next, you should diagnose the ignition and the ignition module. If malfunctions are found, then it is necessary to replace or contact the service center to repair the parts.

Fault code: F05

Indicates a malfunction of the control box. The error appears due to the fact that the air pressure switch does not open when the burner starts. Also, the relay may not close when the ignition load is reached. To determine the cause of the problem, the Air / Flue gas system must be inspected.

When examining it, you can find the following problems:

• The chimney is overgrown with ice. The removal of combustion products and their intake is difficult. The problem is solved by removing the build-up of ice.
• Improperly installed coaxial chimney. Correct installation must be carried out.
• The fan is out of order. In this case, you need to replace the part.
• The melted venturi must be replaced.
• The pressure switch needs to be replaced.

After replacing the air pressure switch, the error disappears.

Fault code: F08

The error is caused by the blocking of the solenoid valve relay. In this case, the burner of the device does not turn on.

It is necessary to check the functionality of the relay, the valve itself, as well as the connecting cables. The lock can be released after a reset or reboot of the device.

The solenoid valve is checked by fire or instrumentation. In the first case, a new thermocouple must be installed. Then light the pilot and bring the flame to the end of the thermocouple. If the automatics work, then the valve is working properly. In the second case, it is necessary to dismantle the sensor, insert it into the repair contact and apply voltage. If the valve closes, then the automation is in order.

Fault code: F10

When this error occurs, the device continues to operate in continuous operation. F10 code signals a short circuit gas boiler sensors. The outside temperature sensor and the room temperature sensor must be inspected.

If the indicators have a significant deviation, then the sensor should be replaced.

Fault code: F18

The error occurs when one of the two sensors is opened. The problem is detected when checking the outside temperature sensor cables and room temperature sensor connections. If the contact has come off, then you need to firmly connect it back. If the cables are damaged, they must be replaced.

Fault code: F30

Error F30 appears when the unit temperature sensor is short-circuited. When it appears, the user needs to inspect the boiler temperature sensor. If an external examination does not reveal a problem, then it is necessary to disconnect the cables from the sensor and measure the resistance. If, when comparing the resistance indicators with the curve, a strong deviation is detected, then the part must be replaced.

Fault code: F38

This error appears when the boiler temperature sensor is broken. When it appears, it is necessary to inspect the sensor, identify the location of the cable break, replace or connect the cable.

Fault code: F51

The display of error F51 signals that the boiler has stopped heating water. The reason is a short circuit of the sensor.

Checking the sensor that measures the temperature of the leaving water is carried out as follows. The cables are disconnected first. The resistance is then measured and compared with the curve. If a significant deviation is found, the sensor should be replaced.

The resistance of the cylinder t sensor must also be checked and compared with the curve. Before checking, disconnect the plug from the cable harness located on the controller.

Fault code: F59

The cause of the F59 error is the opening of the sensors. Check the connection of the water temperature sensor cable and the connection of the cylinder t sensor plug. If a disconnection is detected, then you must carefully reconnect the plug.

Fault code: F70

The F70 error code signals a malfunction of the outdoor unit. The error is displayed due to a short circuit of the S1 collector temperature sensor, which is connected to the external expansion module. When this code appears, you need to check the sensor for a malfunction.

Fault code: F78

The error is associated with the opening of the collector t sensor S1 installed on the external expansion module. It is necessary to check the condition of the sensor cables and the contact tightness.

Fault code: F80

This error also signals a malfunction in the operation of the external expander. The reason is a short circuit of the temperature sensor S2.

Disconnect the sensor cables and check its resistance. If the values ​​deviate from the curve, the sensor must be replaced.

Fault code: F88

The error occurs when the electrical contact with the lower cylinder sensor S2 connected to the external expansion module is lost.

It is necessary to find out the cause of the opening and eliminate it.

Fault code: F90

Fault F90 signals a short circuit of the upper temperature sensor S3 of the DHW cylinder installed on the external expansion module.

It is necessary to diagnose the sensor.

Fault code: F98

The error indicates the opening of the S3 sensor. It is necessary to check the sensor for openings, connect the cables tightly or replace them in case of mechanical damage.

The codes of violations in operation and their decoding adopted by the manufacturer of boilers with the Master Gas logo will acquaint next article, which will be useful to both real and potential owners of units of this brand.

Conclusions and useful video on the topic

Error F05 and how to fix it:

Error F02 on the Vitopend 100-W boiler display:

Each malfunction code that appears on the display of a gas boiler indicates a problem in a specific unit of the device. When carrying out repair work, it is imperative to turn off the power supply to all parts of the heating device. You also need to close the gas valve and stop the gas supply.

Elements that perform protective functions should not be repaired for reasons of operational safety. In the event of a breakdown of Viessmann components, they must only be replaced with original branded parts or spare parts authorized for use by an authorized representative manufacturing company.

Please leave comments in the block below, ask questions, post photos on the topic of the article. Tell us about any malfunctions in your boiler. Share ways to solve the problem.