Main malfunctions and error codes of Vailant gas boilers - decoding, causes of occurrence, solutions

The automatic control unit for gas boilers Vaillant is equipped with a self-diagnosis system. This is a complex of sensors that continuously send signals to the processor and provide communication with all components of the boiler. If the signal from any sensor disappears or changes, a code indicating the problem that has occurred, or an error code, appears on the display.

The self-diagnosis system is a useful and often necessary option that makes it possible to promptly detect dangerous faults and prevent the failure of expensive equipment.

Causes of malfunctions

German equipment is designed for operation under normal conditions. European requirements for the quality of power supply, water and gas pressure are very strict, and the boiler operating mode is designed to meet the standard indicators of all systems. However, often the condition of the networks does not meet the requirements, which immediately affects the operation of the boiler.

The main problematic element is grounding - if the electrode is not connected to the circuit, or is missing altogether, the operation of the device becomes impossible. In addition, Vailant boilers are sensitive to supply voltage and react extremely painfully to low (or high) values, fluctuations or supply failures.

Expert opinion

Grebnev Vadim Savelievich

Heating system installer

All users are recommended to install a voltage stabilizer, and this must be done before connecting the unit to the network for the first time.

Another problematic factor may be the pressure and purity of the gas. If these indicators do not meet the standards, the operation of the boiler will be constantly interrupted by a self-diagnosis system that detects problems in the fuel supply system. Since the gas line poses a considerable danger, the reaction of the control unit can be quite severe - up to the complete blocking of the boiler.

Most common hardware problems

F20/F22/23/24 (F10|F11) – overheating.

Errors occur when the volume of coolant in the system decreases, a sharp increase in temperature, or an exorbitant difference in temperature at the outlet and inlet to the Vaillant.

Recommendation: fill the circuit with water, bringing the pressure to normal (2±0.5 bar). Reset and start up the boiler. Repeated occurrence of the error is evidence of a problem.

Probable Causes

1. Leak. An autonomous circuit is a closed and closed system: natural evaporation of liquid is excluded. Loss of coolant is possible only in the event of mechanical damage or leakage. It is easy to find the problematic section of the route (device) by inspecting the house for signs of dampness, stains and streaks. Leaks rarely occur in the Vailant boiler itself: more often in the joints of pipes or heating radiators.

2. Reduced circulation rate. The coolant moves more slowly, and the boiler burner operates in the specified mode. Hence the overheating and Vaillant's error. What is the reason?

• Heat exchanger
• Pipe

Airlock. It is easiest to identify and mitigate such a problem. It is necessary to check all radiators for the degree of heating: a sharp temperature drop in individual sections of the circuit will indicate the “culprit”. Even if there are automatic valves, you should bleed them manually - they often fail due to poor quality water treatment.

Pump. The boiler overheating error is caused by stopping the device or reducing the shaft speed.

Vaillant boiler pump

First of all, the supply voltage and the set speed are checked. Incorrect operation of the Vailant pump may be due to salt deposits on the impeller. It is necessary to dismantle the pumping device, perform partial disassembly and wash it. After starting the boiler, the overheating error disappears.

Heat exchanger. The formation of layers in its cavity is one of the probable reasons. A gradual decrease in the diameter of the channel negatively affects the circulation of liquid, hence the overheating of the Vaillant boiler and the error.

Recommendation: if there is an alternative heat source at the site, the device must be removed and sent for service. Self-cleaning is ineffective, and after starting up, the Vailant boiler may start up again in a month or a month and a half. High-quality maintenance involves filling the cavity of the heat exchange device with an aggressive liquid, leaving it for at least a day, followed by flushing under pressure. This cannot be done on site.

F26 (F07) – problem with gas fittings.

You should ensure the integrity of the wires and the reliability of the contacts. It is not advisable to change it yourself - you also need to configure it correctly.

F27 – flame simulation error.

The probable cause is the ionization sensor: shorted wires, dirty electrode, dampness. If the boiler has been idle for a long time, you need to remove the casing and dry it (with a directed stream of warm air).

F28 (F04) – unsuccessful ignition.

There are many reasons for this error to appear. You can independently check only the flow of gas to the boiler burner, its pressure, the reliability of the signal circuits and grounding. Other defects - in the meter, main filter, Vaillant fittings, transformer, electronic board - must be determined by a specialist.

F29 – boiler malfunction, problem with re-ignition.

Probable causes of errors during autonomous gasification: gearbox failure, icing, LPG production. The remaining faults are identical to F28; they cannot be determined independently.

F33 (F05) – incorrect fan operation.

The error is caused by its breakdown, failure of the flow switch, or a malfunction in the electronic module of the boiler. If the power and signal lines are not damaged, you need to contact a specialist.

F68 – unstable flame.

Probable Causes

• Unstable pressure in the line.
• Air leak. If Vaillant runs on LPG from a cylinder group, check all connections.
• Problem with the boiler ionization sensor. Its contamination may be the cause of error F68: remove carbon deposits.

• Vaillant boiler gas valve is clogged
• Debris in gas valve

Everything else is due to incorrect operation of the gas fittings and boiler burner. You can service the nozzles yourself: a vacuum cleaner, a toothbrush. If after this the Vaillant error does not disappear, call a technician.

– Pressures greater than 50 mbar are not detected.

Basic error codes

An error code is an alphanumeric designation of a problem that has arisen in some part of the structure.

The most common mistakes:

The above list shows only the most common errors that appear on the display most often. A complete list can be found in the user manual included in the package. It is recommended to keep it on hand so that if an error occurs, you can quickly find the code in the list and determine the malfunction.

Vailant boilers produce not only error codes, but also messages about the current operating mode. They begin with the Latin letter S so as not to confuse users. Codes S.0-S.8 indicate the status of the heating mode, and messages S.10-S.17 appear during hot water preparation.

Diagnostics

Each Vailant boiler has a diagnostic system that is part of the electronic unit. Information about the state of the unit is displayed on the LCD display in the form of a code (including about past errors).

Before a specialist arrives, you can evaluate the performance of the device yourself:

• Check all inlet and outlet connections for leaks (this includes outlets for carbon monoxide, condensate and domestic hot water).
• Check: there are no contaminants in the reduced pressure chamber.
• Check all electrical connections: whether the connectors and plugs are tight.
• Check the condensate drain and siphon for the presence of salt and limestone deposits. If necessary, clean.

Inspect the gas burner - it most often becomes clogged with carbon deposits. The inner walls of working chambers and chimneys also need to be cleaned. There is not a lot of soot in gas equipment, so the user will not have any major difficulties.

How to troubleshoot problems

Most sensors in the self-diagnosis system are thermistors that are triggered when control parameters change. Situations often arise when small fluctuations in pressure or temperature cause a false alarm of the sensor, which issues a shutdown or blocking command.

Troubleshooting Methods

Therefore, the first action of the user when an error is detected on the display should be a reset (this is done in different ways on different models; the user manual contains detailed explanations on this topic). If after several attempts (usually they try to reset the code three times) no positive results are obtained, proceed to more serious actions.

Expert opinion

Grebnev Vadim Savelievich

Heating system installer

Methods for solving emerging problems depend on the type and purpose of the sensor. Most of them require replacement or restoration of broken contacts. However, some problems have to be resolved in more complex ways - checking the condition of the gas equipment, fan, pump and other components of the boiler.

In each case, it is necessary to perform a certain sequence of actions:

• specify the meaning of the error code in the instructions;
• find the problem unit (part, element) in the boiler design;

• decide on the method of repair (restoration or complete replacement);
• direct repairs.

In some cases, it is necessary to restore individual structural elements of a particular unit. For example, if a plastic impeller fails, it is not advisable to purchase a completely new fan - it is enough to buy the impeller itself and replace the defective part.

However, situations often arise when there is simply nowhere to buy the necessary elements. In such cases, they try to restore the functionality of the problematic part (at least temporarily), but the search for a replacement does not stop. Stopping a gas boiler means a lack of heat and hot water, which is unacceptable in the Russian climate. Therefore, the solution to emerging problems must be immediate and as effective as possible.

Connecting a room thermostat

A room thermostat is a device that controls the temperature in a room and regulates the heating system accordingly.

Using this device allows you to save about 20% on heating. This effect is achieved through more rapid adjustment of the system temperature. The boiler's own sensor is guided by the temperature of the coolant.

When it warms up outside, the house becomes too hot, but no changes occur for the boiler system as long as the coolant temperature is within the specified limits.

The room thermostat is guided by the air temperature, so it immediately sends a command to change the heating mode.

To connect the device, the corresponding contacts on the control board are used, connected in normal mode by a special jumper.

Is it possible to carry out repairs yourself?

Current regulations prohibit self-repair of gas equipment. This point must be taken into account when starting restoration measures. However, there are many ambiguities in this issue - there are other components in the boiler design that are not directly related to gas equipment.

If the secondary heat exchanger or boost fan fails, the gas supply system will not be affected in any way. To solve such problems, you need to call a technician from the service center. He has all the necessary approvals and permits; gas service inspectors will not have any questions.

Another issue to consider is the validity of the warranty agreement. The conditions are quite strict - installation and initial start-up must be carried out by employees of the warranty workshop (service center), routine repairs or maintenance of the boiler must also be carried out by specialists.

Independent intervention in the boiler design is regarded as termination of the warranty agreement at the user’s initiative, and you will no longer have to count on free repairs. Even replacing the plug on the power cord can be considered such an intervention, therefore, in any situation, it is recommended to immediately call a service technician.

If you repair it yourself, the boiler will be removed from the warranty.

If there is no way to contact specialists, you have to act at your own peril and risk. When purchasing a boiler, you must immediately find out where the nearest service center is located and whether there is a possibility of quickly solving possible problems.

If the warranty workshop is located too far away and a technician does not come to your home, it makes no sense to conclude a warranty agreement.

Advantages and disadvantages

Design features and functions affect the quality of equipment. If you carefully read the instructions for the Vaillant gas boiler, you can highlight several main advantages:

• built-in security system;
• fault testing sensor;
• heat exchanger with plate structure;
• significant tank capacity;
• simple chimney system.

The safety device allows you to protect the device from an unexpected decrease in fuel supply, overheating or blocking the flow of water, or extinguishing the fire inside the burner. It also regulates the operation of the boiler in the event of a power outage, freezing or malfunction of the heat exchanger. If problems occur, the fault sensor will display an error code on the screen. It is used to diagnose problems.

The peculiarity of the heat exchanger structure extends the life of the boiler, since the plates are highly reliable, durable and wear-resistant. The storage tank capacity is 150 liters, which ensures the satisfaction of all household needs. The smoke exhaust system is easy to install and does not pollute the environment.

Main disadvantages:

• the need to use only purified water;
• shutdown during power outages;
• insufficient traction;
• incomplete set.

The boilers do not have an expansion tank, so it will not be possible to maintain coolant flow. Normal operation of the unit will be ensured only by constant inlet pressure of cold water. Open designs do not have a built-in fan, so the draft is weak. Automatic systems turn off the boiler in case of power failures. You will have to start it manually, which consumes more gas and reduces efficiency. You cannot use antifreeze or water with impurities for heating; only distilled or filtered liquid is suitable. For the first start, it is advisable to first boil and settle the water.

Setup and management

Handling Vaillant boilers involves competently transferring them from one mode to another. The question often arises of how to properly turn off the heating system for the summer so as not to pay extra for gas and not overheat the house. The solution to the problem is to close the heating circuit for a short stroke, using a tap and jumpers.

If the equipment is made according to a scheme with artificial circulation, everything will be even simpler: you should disconnect the circulation pump from the scheme and seal the boiler inlet pipe. Trying to solve the problem by installing additional speakers is impractical and not very economical

It is important to remember that you will have to ensure a stable temperature by normalizing the flow of hot liquid. It is necessary to pump up the expansion tank if the pressure level continuously decreases and increases, changes unpredictably

A steady drop in pressure in the system cannot be easily eliminated; it is imperative to find the place where the coolant is leaking and eliminate the cause of the problem. The search for defects should be carried out on radiator plugs, connecting lines and where fittings and pipes are soldered.

If pumping the tank does not produce results or they last too short a time, you need to inspect the tank. Often its outer shell depressurizes and allows air to pass through. But even more often the performance of the spool valves is disrupted, which also begins to leak.

The pumping of the tank itself is carried out in the following stages:

• turn off the boiler, supply and return valves;
• open the drain fitting until it is completely drained;
• connect the pump unit via a spool, under no circumstances blocking the fitting.

Any type of pump is useful for the job; You can take a car gauge and a pressure gauge from the car too. The air pump is pumped until water flows out of the outlet fitting. Next, release the air and repeat its introduction, continuously monitoring the pressure gauge readings. It should show 1.1–1.3 bar; more precise information is provided in the technical documentation. Now you can close the pouring fitting, open all the previously closed taps, feed the boiler in the normal way to 1.2–1.5 bar, and then start warming up.

It is especially important to monitor internal pressure if the house or other structure is visited only periodically. It is no secret that the stability of power supply is now far from ideal.

And if the power stops, the boiler stops working, so the pressure inside the tank can drop due to cooling below what is required for the boiler to operate. Even after the power supply is restored, the boiler cannot warm up the house, because soon the uncontrolled house presents a sad sight - pipes and radiators torn from ice everywhere. Therefore, the pressure in the expansion tank must be constantly monitored. No less bad is the situation in which the pressure level continuously increases. Of course, a well-chosen and correctly installed safety valve corrects the matter to some extent, but it is better not to rely on it, since this is still more of an emergency measure. It is always worth remembering that pressure control deserves increased attention.

Decoding

Error f61 indicates incorrect operation (failure) of the gas valve of the Vailant boiler: violation of valve control. Replacing a unit does not always lead to a positive result - the code is triggered by a number of reasons, and the problem is not necessarily in the main battery: it is more related to the Vaillant electronics. Below is a recommended algorithm of actions that reduces troubleshooting time.

What to do

Step 1

Restart. Error f61, like others, is often caused by instability of the parameters of the power supply network of the Vailant boiler. Press the button and hold for 5 seconds: Reset, “Network”, “On” (depending on the type of unit). Often this action clears the fault code.

Button for resetting error F61 on the control panel of atmoTEC pro, turboTEC pro Vaillant boilers

Connect the Vaillant boiler via a voltage stabilizer

Step 2

Assessing the condition of signal lines. Loss of gas valve control, error f61, may be the result of unreliable contacts, broken wires, or short circuits. Remove the casing from the Vailant boiler, inspect the cable connecting the main battery to the electronic board

Particular attention to the connectors: condensation and oxides cause a break in the control circuit. Detected defects are eliminated independently - the services of a specialist are not needed

Step 3

GK testing. Depending on the type of Vailant boiler, gas fittings differ in design features: number of valves, control voltage values, settings for the type of fuel (main, liquefied). But the user can identify a number of problems when searching for the cause of error f61 on his own.

Replacing the gas valve in a Vaillant boiler

Check what

• Windings of coils, a stepper motor that controls the second valve. Testing for serviceability involves measuring resistance. In the event of a short circuit, the multimeter will show R = 0, and an open circuit - ∞. Error f61 is also caused by an interturn short circuit, but to diagnose it you need a special device and accurate data on the characteristics of the winding (they are not in the service manual).
• A gas tube connected to the gas inlet port. “Garbage” in the cavity (according to experience with Vailant boilers) is a common cause of errors, and not only f61. Sludge is applied into it from the main line, passing through the filter grid. Clean it and code 61 will disappear.
• Internal channels of Vaillant gas fittings. The method for eliminating error f61 is similar - blow it out, remove any trapped fractions from the assembly (graphite chips are often found).

Step 4

Inspection of the electronic board. The ECU controls the operation of the gas valve, and the loss of “visibility” between the components of the Vailant boiler, changes in the voltage values ​​supplied to the main valve coils and the engine are the causes of error f61. Diagnostics are carried out in a workshop, on a bench: different operating modes of the heating unit, emergency situations are simulated, and the response of protection circuits is assessed. To eliminate error f61, you need to inspect the board yourself.

Check the Vaillant boiler control board

What to pay attention to

• Mechanical damage: cracks, splits of panels, parts bodies.
• Dark spots, melted areas of the circuit.
• Breaks, peeling of tracks.
• Connector condition. Moisture and oxides in the boiler board connectors are the cause of error f61.
• Condensate. Drops of water on the surface lead to short circuits and Vailant fault codes.
• Dust. When saturated with vapor, it becomes a conductive layer. Remove it and error f61 will disappear.
• Relays that close circuits through which control voltages are supplied to the gas valve and stepper motor. There are several of them, and you can “calculate” what you need using the tracks. Error f61 is often associated with burning of the contact group. It can be removed by replacing the corresponding relay. But this advice is for those who have experience in repairing electronic devices.

If you cannot resolve the problem on your own, contact an authorized service organization. When submitting an application, indicate the type of Vailant boiler (inscription on the marking plate), year of manufacture. A more thorough diagnosis of the heating unit is the job of a professional.

Decoding

Error F27 informs about a false flame. The electronic board records the combustion process after sending a command to the valve to block the channel. Knowing the composition of the control circuit, it is easy to outline the circle of “suspects”: ionization sensor, gas valve, control unit of the Vaillant boiler.

Button to reset error F37 for boilers

The “behavior” of electronics is often unpredictable. Therefore, for a number of codes from the fault table, the reasons are similar. When troubleshooting error f27 Vaillant, it is recommended to follow the following algorithm.

First steps

Parasitic (induced, extraneous, false) signals are formed when the electronics of the Vailant boiler malfunction.

Restart the heating unit. If error f27 Vaillant is the result of a power surge, it will be removed.

Button to reset error F27 on the control panel of atmoTEC pro, turboTEC pro Vaillant boilers

Check Uc value

. For stable operation, Vaillant needs to be provided with ~230. Imported equipment reacts to deviations in voltage parameters (f, U), for this reason it often produces errors.

For owners of facilities where such situations are not uncommon (power line breaks, problems at a substation), the optimal solution is a UPS. The units are available in different configurations (with built-in batteries or external ones) and are capable of ensuring stable operation of the boiler on batteries for a long time.

Assess the reliability of grounding. Checking the circuit by inspection will not give a real picture. It is easy to verify the quality of the grounding of the Vailant boiler by checking the presence of potential on the metal of the heating unit with an indicator screwdriver - the glow will indicate the cause of error f27.

The problem with stray currents and false codes is solved by installing a dielectric coupling on the gas main in front of the Vaillant.

Connecting a dialectical coupling