Decoding error codes in Vailant heating boilers

The Vailant double-circuit gas boiler provides heating of the house and supply of hot water. Experts recommend these boilers because of their efficiency in use, operational safety, ease of installation and affordable price.

Which boiler to choose?

Vailant gas boilers can be floor-mounted or wall-mounted. Floor-mounted ones are more powerful and durable. Wall-mounted ones take up less space.

The Vailant double-circuit wall-mounted gas boiler can be selected from a large model range. One of the main indicators is the power of its power. You need to calculate how much hot water your family spends on average. Based on this, you can choose a boiler.

• For a boiler power of 20 kW, the maximum water flow is 9.5 l/min.
• 28 kW – 13.4 l/min.
• 36kW – 17.2 l/min.

The Vailant double-circuit gas boiler can operate on natural and liquefied gas. The consumption of liquefied gas is less than natural gas. The device is converted to another type of gas by readjustment.

Decoding

Error f26 informs about a malfunction in the functioning of the gas fittings of the Vailant boiler. The control valve, which meteres the supply of “blue fuel” to the burner, changes position under the influence of the stepper motor drive. The control signal to the stepper motor is supplied from the electronic board in the form of a “series” of pulses: the number is determined by the set Vaillant operating mode.

Error F26 is displayed on the control panel of the Vaillant boiler

The EPU, by adjusting the number of steps, determines the degree of opening of the gas channel and the amount of fuel passed through. The movement of the spindle depends on the interaction of the magnetic fields of the coils. Therefore, the cause of error f26 of the Vaillant boiler must be sought in the gas fittings and control unit.

There is no clear recommendation for eliminating the code, so the manufacturer’s instructions advise that if such a malfunction occurs, contact a service organization. The article was written based on the author’s personal experience and analysis of the exchange of opinions of experts and users on solving the problem with error f26, found on thematic forums.

Electronics present the most unexpected surprises: different codes are caused by similar problems. When looking for the cause of the 26th error, before calling a service representative, you should try to fix the defect yourself.

Restart the boiler

Depending on the type of Vaillant, press the RESET, “NETWORK” or “ON” button. If error f26 is false, which appeared after a power surge, will disappear.

Button to reset error F26 for boilers atmoTEC pro, turboTEC pro

Check grounding

The potential on the body of the Vaillant boiler is a common cause of errors. It is detected by touching the metal part of the unit with an indicator screwdriver. Interference (stray currents) lead to malfunctions of the electronic board and false fault codes.

The problem is solved by installing a dielectric coupling on the gas pipe, in front of the boiler.

dielectric coupling

It is not for nothing that users note that error f26 Vaillant appears after a severe thunderstorm. Violations in the functioning of the heating unit are typical when independently arranging grounding without taking into account the requirements of the PUE and the manufacturer’s recommendations.

Inspect the inside of the boiler

The condition of the electrical circuits between the gas valve block and the electronic board and the reliability of the connections are assessed. Melted insulation and condensation initiate short circuits, the signal is “set”, the command to control the Vaillant boiler valve is lost, and error f26 is displayed. Detected defects are easy to eliminate.

Checking the signal lines in the Vaillant boiler

Damage to the EPU is also visually determined. This is indicated by swollen housings of electrolytic capacitors, microcircuits, cracks, chips, and burnt tracks.

Vaillant boiler control board

Perform cleaning

Dust is a likely cause of error f26. Accumulating on the fittings parts, the control board of the Vailant boiler, it gradually absorbs moisture, turning into a conductive layer. Dirt is removed carefully using a cotton swab, without using alcohol-containing or other aggressive liquids. It is recommended to practice regularly, especially for Vailant atmospheric boilers. This minimizes the risk of errors appearing on the unit display.

If you can’t remove the f26 code, contact an authorized service. It is not advisable to independently “pick” the board using advice from the Internet and various kinds of “experts” for a number of reasons.

• EPU is expensive, from 7800 to 14300 rubles. For diagnostics in a workshop at a stand, restoring the functionality of the unit, you will have to pay no more than 1000.
• Replacing the processor may not give any results - depending on the type of Vailant, the year of manufacture, the “firmware” is different.
• The dense arrangement of parts involves spot soldering. Performed on a machine with temperature control. Otherwise, overheating and damage to element housings are inevitable.
• The lack of schematic diagrams forces the user to act “blindly”. As a result, the boiler remains idle for a long time.
• Sometimes the cause of error f26 is a malfunction in the display board (display panel). It cannot be repaired - it can be changed.

When submitting an application, indicate the release date and type of Vaillant. The technician will replace the EPU in a matter of minutes, the problem with error f26 will be solved quickly.

What do the error codes mean?

In many cases, there is no need to disassemble the device yourself or guess what the problem is. Error codes provide all the necessary information to the consumer. But you definitely need to know them. A symbol starting with S indicates a certain status of the device. And codes starting with F indicate certain failures.

When you see this or that conditioned signal for the first time, you should not be afraid. You need to try rebooting the electronics. Only when the same code appears again do you need to take special measures. F0, as well as F71, indicates that the circuit supplying the thermal sensor that measures the temperature of the coolant is broken.

You need to find out things like:

F1 demonstrates that the temperature meter on the return line has broken. F2 says that the thermal fill sensor is malfunctioning. When the F3 signal appears, it is easy to understand that the circuit of the same sensor, but already responsible for controlling the drive, is damaged. Error F5 can only be seen in Atmo wall-mounted boilers, and it means that the connection with the external smoke removal indicator has disappeared. Code #6 states that there is a problem with the wiring of the internal sensor located in the tap.

Using code No. 10, specialists identify short circuits in the supply thermistors. F11, F13 show the same status, but only for the return thermistor and hot start measuring device respectively. A closed external detector for gaseous products is characterized by two errors at once - F15 and F16. Code F20 indicates that the system is malfunctioning due to excessive heating. But F22 talks about another point - there is not enough water. A similar picture is indicated by code F23, which is often associated with malfunction of sensors, pumps, or low performance.

Signal No. 24 indicates that not only the coolant level has decreased, but its heating has also increased significantly and the pressure has decreased. F26 means that there is a failure in the gas fittings. You should also suspect an error in connecting the servomotor. F27 is displayed if a flame is detected when the fuel valve is closed. More serious than F28, this code appears when it is impossible to start the burner.

You will have to control the meter, fittings, pressure measuring relay, and the main module.

F29 is displayed when the fire goes out due to interruptions in the gas supply. All that remains is to wait for his approach to be restored. If the wait is prolonged, you will have to contact the service responsible for the supply of blue fuel. It is also useful to check whether the boiler is properly grounded. Only in condensing boilers does error F32, F37 occur. It reports that the fan does not rotate as it should at a particular moment (other models demonstrate this with code F38).

The TurboTEC model has a special error not found in other devices - No. 33. It is easy to find out from it that the relay that measures the pressure does not work. The F36 signal arrives when the draft meter detects its weakness and the penetration of combustion gases into the boiler room. And F42 is displayed if the resistor responsible for conditional coding has stopped working. When signal No. 49 arrives, you need to check the status of the eBus information bus.

Code 53 indicates an incorrect setting of the combustion process. At signal 54, you need to start eliminating malfunctions in the fuel supply, in this case it is worth sequentially opening the valve, increasing the pressure and visually assessing the serviceability of the shut-off valves. Code 56 indicates a malfunction of the main parts of the fuel burning unit. If connecting the plug does not solve the problem, you need to check the fittings. And code 57 is issued when setting the “Comfort” mode with an incorrect adjustment. It is also worth suspecting that the ignition electrode has become corroded.

If the cleaned parts continue to perform poorly, you will have to install a completely new part.

F61 may illustrate either a shorted cable, an open circuit, or a fuel valve failure. The signal F62 determines the delayed shutdown of the valve caused by poor response of the control electrode. The display of the number 63 indicates a so-called EEPROM failure, which can only be repaired by service centers. Violations shown by numbers 64 and 67 indicate that the electronic “stuffing” of the boiler is damaged or the sensors have gone wrong. A relatively minor problem is error 70, which occurs when the step of entering the code for a new boiler is skipped after installing a replacement display and electronic components.

The F72 index allows you to recognize violations in the thermal line sensors responsible for the supply or located on the return circuit. F75, as it were, notifies the boiler owners that even starting the pump does not help raise the pressure. You will have to release the air accumulated in the system, adjust the settings of the bypasses and expansion tanks. F35 is a kind of “partner” of the 36th error.

This error appears when the following malfunctions occur:

F76 lights up on the display when the primary heatsink is too hot. And F77 indicates that the diverter valve or pump responsible for condensation is working too poorly. F51 signals about the overturning of the draft and obviously incorrect operation of the chimney. Simultaneously appearing signals 80 and 91 immediately indicate a short circuit in the secondary radiator sensor. If errors 81 and 91 are combined, there is a malfunction of the loading pump.

You can fix this error by doing the following:

F83 notifies about an incorrect measurement made by thermistors on the receiving and return lines. Simply add coolant or adjust the placement of the thermistor. Codes 84 and 85 also indicate incorrect information from thermistors, but problems need to be resolved differently - by swapping blocks or eliminating other installation defects. Deformation F93 demonstrates that combustion is not occurring properly. When cleaning the Venturi nozzle does not help, you need to change the nozzle to a more correct device. The Con defect indicates that the exchange of information with the control equipment is disrupted and you will have to contact a service organization.

The Fxx code talks about software failures; 5ER is not so much an error in the usual sense of the word as a reminder of the need for maintenance.

Vaillant boilers can also produce intermediate messages that are not errors. Thus, S0–S8 tell consumers about the running heating mode. When the boiler prepares hot water, signals S10–S17 are shown on the display.

Other status signs are as follows:

It happens that the heating seems to be running, but the regulator instructs the boiler to operate at +20 degrees. In this case, signal 36 is displayed on the screen. But code 41 says that the nominal pressure is developing too high inside. S42 can be displayed when the burner is not working, when the valve on the outlet is triggered or the condensation pump is damaged. S51 is a condition where combustion gases enter the room.

Error 53 is detected when there is a lack of water. The boiler will correct the situation or wait for help from the owner in this within 150 seconds. S54 means the system waits for 20 minutes for action. There is no cause for alarm when status S98, 96 or 97 appears, since these are signs of operation in test mode.

The occurrence of all of these problems can be minimized by promptly inspecting the boiler and carrying out maintenance.

Check what

Traction control system

In Vailant Turbo series boilers, the volumetric air flow (after ignition - exhaust gases) is determined using several devices that are structurally connected.

Pitot tube ruptured in Vaillant boiler

Complete set of manostat with Vaillant boiler tubes

Vaillant boiler pressure switch

Connect multimeter probes to the terminals to measure resistance. In the initial position, the microswitch contacts are open, therefore, R = ∞. Close the inlet port of the manostat with your lips and take several breaths. When the MF is triggered, characteristic clicks are heard, and the multimeter shows 0. If there are no complaints about the sensor, check the reliability of the connection of the electrical circuits.

Fan

In practice, error f37 indicates low speed. The shaft rotation speed drops for a number of reasons, and troubleshooting should begin with an external inspection of the turbine. The code is called:

Boiler fan vaillant

• impeller contamination. The weight increases, which affects the number of revolutions. Cleaning removes error f37;
• bearing destruction;
• interturn closure of the winding.

If error f37 of the Vaillant boiler does not disappear after removing dirt from the fan, the turbine must be replaced. It is impractical to test, disassemble, or repair it at home.

Chimney

Another error indicates a problem in the smoke exhaust duct. But if the thrust is reduced, the 37th may also appear. The instructions say that the pressure sensor operates in the range of 68–80 Pa. Inspect the pipe outlet, remove icicles, ice crust, clean the filter from dirt - a service technician is not needed for this.

The chimney is clogged

Electronic board

The “brain” of the Vaillant boiler receives signals from sensors, generating corresponding errors. Fault codes are caused by malfunctions of its operation. Testing cannot be carried out without a simulator, but visual diagnostics often help resolve the problem.

Vaillant boiler control board

Reasons for the error

• Board deformation.
• Dark spots are the result of thermal exposure.
• Unreliable contacts.
• Breaks, peeling paths.
• Damaged parts housings.
• Condensate.
• Dust. Gradually gathering on the surface of the boiler board, absorbing moisture, it turns into a conductive layer. Careful cleaning of the EPU eliminates error f37.

Error f33 vaillant how to fix and what to do?

Occurs only in turbocharged boiler models. The source of the error is the pressure switch in the exhaust pipe. The operating logic of all modern gas boilers is approximately the same. When a request for ignition is received, the control board turns on the fan (smoke exhauster), which creates a vacuum. When the required draft is achieved, the contacts of the differential relay close and thereby transmit a signal to the board to open the gas valve and ignite the burner. Accordingly, if there is no signal from the relay or it is in a closed state after the fan is turned off, the vaillant automation generates error f33.

Vaillant boiler error f33

causes:

The fan does not work (can be checked visually)

breakdown of the pressure switch (condensation may accumulate in the tubes, which, flowing into the sensor, renders it unusable;

error when installing the exhaust pipe (condensation can also accumulate and flood the relay)

clogging of coaxial pipelines, preventing normal air flow

pitot tube clogged (accumulated dirt or insects)

You can check the operation of the relay by creating a vacuum yourself through the tube (a characteristic click should occur). It happens that the relay “sticks”, i.e. in normal condition it will be closed, which can be checked with a conventional multimeter. In this case, it will have to be replaced.

It happens that the tubes themselves or the pitot tube are damaged, for example, from exposure to high temperatures.

The slightest change in shape can affect the readings and cause error F33.

It is worth noting that this is a problem with almost all gas boilers. Some manufacturers solve this by installing a special extension (this is what BAXI did) to collect condensate, and some even make heated tubes to evaporate it.

Repeated breakdown

The music didn’t play for long; my favorite Vaillant gas boiler broke down again. At first I got error f33 and again f28, which means a problem with the gas burner. Since the Vailant display was acting up, naturally the fault was on the control board. However, one should not rush to conclusions. Like last time, we act according to a clear plan:

1. Disabling equipment.
2. Removing a gas boiler.
3. Carrying out diagnostics.
4. Analysis of the design.
5. Checking elements.

Since I had previously inspected the unit, I decided to check all the main components. I was interested in the condition of the tap, sensors, and pump. I didn’t want to disassemble the unit often, so I thought about how to fix all the problems at once. In a Vaillant gas boiler, some elements are hidden, so it is difficult to get to them without damaging another element.

We are talking about the control board. It is located at the bottom of the structure, and to get there you will have to tinker with the bolts, in my case everything looks flimsy. Finally, the Valiant boiler is open and you can look around. The control board is a regular element, the same as in a computer. When disassembling a gas boiler, it is recommended not to touch the contacts and connecting elements with your fingers again, since greasy stains remain on them. All this can affect the operation of the automation.

Eliminating the error begins with cleaning the contacts. As you know, there are tracks on the control board, and they can be easily cleaned with ordinary office grout. As for the sensors, I just removed the dust from them. Upon inspection, I noticed that the three-way valve was loose and could possibly fail in the near future. This element is located in the upper part of the structure and is responsible for shutting off the gas.

In the store I picked up a similar three-way product, the most interesting thing was with the control board. Finding a similar variation is problematic, fortunately, the exact product code is indicated on it, so I was able to order it online.

Error F28 may also appear due to a gearbox malfunction. The element is responsible for gas pressure and is connected to the meter. When I had suspicions about the gearbox, I initially carried out diagnostics; it was necessary to check the settings. First of all, turn off the gas valve

You need to pay attention to the display. If the error code disappears, it means the element needs to be replaced. It happens that everything is fine with the magnet, but the ignition transformer suffers

Soot often accumulates on it and the gas boiler refuses to work. Checking the pressure is not so easy, since it requires removing the casing. Having reached the distribution box, close the shut-off valve. Inside there are several sealing screws that are fixed to the gas fittings. It is only necessary to loosen them a little; the structure is not as strong as it might seem at first glance

It happens that everything is fine with the magnet, but the ignition transformer suffers. Soot often accumulates on it and the gas boiler refuses to work. Checking the pressure is not so easy, since it requires removing the casing. Having reached the distribution box, close the shut-off valve. Inside there are several sealing screws that are fixed to the gas fittings. They only need to be loosened a little; the structure is not as strong as it might seem at first glance.

A digital tonometer is used to check blood pressure. In the instructions you will find exact indicators of normal pressure depending on the modification.

The Vaillant boiler simply does not turn on

If the boiler display does not light up, and you are absolutely sure that it is reliably connected to the power supply, then most likely the board has failed. Unfortunately, the self-diagnosis program does not record internal errors in the operation of the board, and if damaged, the boiler will simply go out. Quite often, these damages can be seen visually when inspecting the board.

We have everything you need to restore the boards of TEC and MAX series boilers. Here is an example of repairing one such case (the power module on the board burned out):

The repair was completed within a day and the payment was handed over to the satisfied customer.

Vaillant is a high-quality and reliable technology, but electronic breakdowns still happen sometimes. The boiler circuit board is one of its most expensive elements, so by contacting us, clients save an impressive amount of money

We have been doing repairs for a long time and all spare parts are always in stock, and repairs take a minimum of time, which is especially important when a breakdown occurs during the heating season

If you are the owner of a Vailant gas boiler, do not wait until something breaks to study the error codes. He who is forewarned is forearmed.

After all, a gas boiler is a complex technique; in the event of an emergency, competent actions will determine how the Vaillant boiler will operate in the future.

Malfunctions most often require a professional approach, but you can do something yourself.

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.

Why does blood pressure drop?

The pressure drop in the boiler has a single cause - a coolant leak. If, after several attempts to increase the pressure using the supply valve, no positive results appear, you should look for a leak in the boiler itself or in the heating circuit.

Difficulty may arise if the boiler is a condensing boiler and is connected to a floor heating system.

Finding leaks in such conditions is extremely difficult. It may turn out that the fault is hidden in the discharge valve connected to the sewer system.

The optimal way to search for causes is to consistently eliminate possible causes of leaks, so that ultimately only one, the correct one, remains.

NOTE!

Certain information can be obtained if you try to determine the intensity of the leak and analyze the throughput capacity of the boiler elements involved.

Vaillant boiler safety

Each Vailant double-circuit gas boiler is equipped with three safety sensors, some models have more.

• Flame sensor. If the fire in the boiler goes out, it immediately shuts off the gas.
• Gas exhaust sensor. It controls the safety of gas outlet and combustion products removal.
• Temperature sensor. It prevents the water and boiler elements from overheating.

Safety is one of the most outstanding advantages of Vailant gas wall-mounted boilers. The intelligent control system that is being implemented into these boilers will simply not allow it to be used if there is the slightest malfunction. Primary and additional sensors regulate the operation of the device, preventing premature wear and tear.

Doesn't restart

There are many reasons for failure to restart a boiler. It is almost impossible to name them all, since most problems one way or another lead to the installation being blocked, and restarting becomes impossible until the cause is eliminated. However, some possible reasons can be named immediately.

For example, the power plug in the outlet may be upside down. Vaillant gas boilers are phase dependent, i.e. cannot work when the contacts are rephased. If a reconnection occurs during repair work, starting the unit will no longer be possible.

In addition, it is possible that the injectors become clogged with soot, which stops passing gas in the required quantity, resulting in immediate blocking upon startup.

Vaillant boiler error F28: how to fix

If you don’t want to understand the reasons and finances allow, of course, you can take the equipment to a service center. However, DIYers recommend not to give up and try to carry out repairs at home.

Please note that we are talking about gas equipment, so precautions must be taken. The unit must be turned off to ensure complete safety.

My actions during a breakdown:

My actions during a breakdown:

1. There is a “reset failure” button.
2. Equipment dismantling.
3. Carrying out diagnostics.
4. Boiler disassembly.

I am familiar with the structure of gas equipment and the first thing I check is the electrodes. My first thought is that the wiring is damaged. If there are exposed contacts, this is the easiest problem to fix. Take a blowtorch, everything falls into place. However, during the first inspection I did not find any problems with the wires; the electrodes are all in place (in theory, the electronic board should receive a signal).

The second point is grounding. It is checked using a tester. The most difficult thing is the valve; according to the instructions, it must withstand a certain pressure. In my case, he was clearly acting up and didn’t even know what to do. I decided to simply replace the element, error f 28 disappeared by itself.

Repair of various models

According to the manufacturer's instructions, the Vaillant TurboTEC Pro 28 kW gas boiler cannot be repaired in such a way that changes occur in the boiler itself, in the water or gas supply lines, in the electrical network or in the chimneys. The threads of all connections can only be tightened and loosened using open-type wrenches. Pipe pliers, extension cords and similar equipment should not be used for this purpose.

Check the pressure as follows:

• the shell is removed;
• The distribution box tilts forward;
• the gas valve is closed;
• the screw in is loosened;
• a pressure gauge is connected;
• the gas shut-off valve opens;
• the device is started at full load;
• The connection pressure is measured.

If you cannot resolve the problem on your own, you should perform the following steps:

• the boiler needs to be stopped;
• remove the pressure gauge;
• check the tightness of the screw;
• fold out the distribution box;
• return the casing to its place;
• wait for gas service representatives.

Both single-circuit and double-circuit boilers, which consume a lot of gas and produce an extremely hot smoke stream, do not require repair. It is necessary to clean and wash the upper heat exchanger. If the hydraulic resistance is low, the company recommends tightening the supply valve. If there is no spark at all, there is no need to waste time cleaning the gas valve. The problem is almost 100% likely to be related to the system electronic board. If the AtmoTEC Plus boiler changes pressure sharply when the temperature changes, it is necessary to pump up the expansion tank.

Causes of problems

In order for possible reviews of boilers of this brand to be favorable, it is necessary to pay great attention to the prevention of malfunctions and their elimination. It is worth noting that not all problems are indicated by codes; some occur without warning. A situation where the boiler does not turn on at all may arise due to incorrect connection of the “zero” and “phase”.

The problem may also be due to the following:

When there is no hot water at all or the boiler does not heat it well, you need to evaluate the condition of the flow sensor. Sometimes it becomes dirty, the liquid moves, but the automation does not command the fan to blow through the firebox and fan the fire. By releasing water from the hot water supply circuit, the pipes are saturated with air. Following this, you need to sharply open and tighten the water taps in front of the boiler in order to remove dirt from the fan or sensor due to pressure drops. If the pressure rises or falls unpredictably while hot water drips from a cold tap, damage to the secondary heat exchanger may be suspected.

You should also check the following reasons:

For instructions on using a Vaillant gas boiler, see the following video.

Decoding

Error f36 should be interpreted as follows: traction violation: falls or the channel is completely blocked. The temperature of the exhaust gases rises sharply, which is recorded by a sensor monitoring the chimney. A corresponding signal is sent to the electronic board, code 36 is generated, and the heating unit stops.

Error F36 is displayed on the Vaillant boiler

The situations in which the Vaillant atmospheric boiler shows error f36 are different: initial startup, when the weather changes, only in the evening hours. The article discusses all the probable causes of the problem - the user will definitely find a solution to the problem.

Where to begin

Imported boiler equipment reacts to instability of the supply voltage. Jumps, phase imbalances, increased (lower) Uc values ​​lead to failures in the electronic circuit, and false errors appear. Before you start searching for the cause of the fault code, you need to restart the Vailant boiler. Depending on the modification, press the Reset, “Network”, “On/Off” button. If the appearance of the f36 symbol is associated with problems in power supplies, the error will be removed.

Reset error F36 on the Vaillant boiler control panel

Advice

The UPS helps eliminate the possibility of displaying false codes. Connecting the Vailant boiler to the home network through the unit guarantees stable operation of the unit even in the event of problems with power lines or a backup power source. Autonomy is provided by batteries (built-in or externally attached).

Connection diagram for backup power to the Vailant boiler

Error interpretation

There is some confusion in the Vaillant manufacturer's instructions and its interpretation.
Regarding error F75, it is said that its causes may be a faulty pressure sensor or circulation pump. At the same time, codes F73 and F74 are indicated in the same table. The first indicates a problem in the signal circuit of the flow switch (short circuit, broken wire, poor contact), the second indicates a breakdown of the sensor itself. The peculiarity of the electronic circuit of Vaillant and Protherm is that it not only controls the operation of the pump, but also the moment it reaches the operating mode. This is how German units differ from boilers of other brands. If within 20 seconds after start-up there is no pressure jump in the system by 50 bar (that is, normal fluid circulation), the automation regards this as a malfunction of the pumping device and issues an error F75, which blocks the Vaillant boiler.

The most common malfunctions and their causes

Despite true German quality, like any other equipment, Vailant boilers are subject to various types of failures. If this or that problem does arise, the device informs the owner about it by displaying an alphanumeric code on the LCD display, including a red light, as mentioned above. Each error has its own code.

If you study thematic forums where boiler owners discuss their malfunctions, the most popular queries are:

• error with code F22, indicating the absence of water in the device or its shortage. It is worth checking whether the pump is jammed, whether the pump cables are securely connected to the water pressure sensor, look at the sensor itself or at the power of the pump. Possible still weak water circulation;
• error with code F28, in which the unit does not start at all. The reasons may be different: the zero and phase are incorrectly connected, the gas is oversaturated with air, the gas pressure level is too low, the control board is broken, the boiler is not properly grounded, a cable break or an error in connecting to the gas pipeline. Some problems can be solved by yourself by looking at the instruction manual. For example, check whether the gas tap is open or change the gas pressure in the boiler settings to 5 mbar;

Error F28 on the boiler display

• error with code F29, in which the burner flame constantly goes out, and new attempts to ignite are unsuccessful. The reasons may be: the gas boiler is not grounded correctly, gas supply failures in the gas system itself, problems with the ignition transformer or gas valve. To eliminate this problem, it is worth checking the gas pressure; it may drop too low or see if there is enough air for normal combustion of the fuel;
• error with code F36 (Vailant Atmo), in which combustion products come out. This problem may occur due to poor ventilation in the room or poor draft in the chimney, or the temperature in the room is too high. You should also check whether there is sufficient space between the boiler and the wall;
• error with code F75, in which the boiler pump works, but the pressure does not rise. There may also be several reasons: breakdown of the pump or water pressure sensor, air getting into the heating system, incorrect connection of the expansion tank or insufficient water pressure. To fix the problem, you can try cleaning the water pressure sensor or you will have to purchase more powerful components.

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?

Vaillant boiler pump

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.

Master's recommendation

When starting up Vailant for the first time, you need to check the installation of the check valve in the system. Incorrect installation blocks the channel, hence the boiler error.

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 , you cannot determine it yourself.

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

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.

Error f75 gas boiler Vaillant

– Pressures greater than 50 mbar are not detected.

Commissioning sequence for Vaillant boilers

• Before filling, it is necessary to thoroughly rinse the heating system (large particles remaining after installation work can damage the actuators)
• check the condition of the automatic air vent on the circulation pump; if it is closed, unscrew it 1-2 turns
• shut-off valves on heating radiators or thermal heads must be fully open
• fill the heating system to a pressure of at least 1 bar (usually 1.3 – 1.5 bar)
• turn on the boiler and check the pressure, if necessary, recharge the system
• Be sure to check the gas deflector for leaks
• Vaillant requires filling the system with prepared water with a hardness of no more than 20 units according to the German calculation system and prohibits the addition of antifreeze or corrosion inhibitors to the system.

After the system is filled, it is necessary to carry out the P0 air removal program, in which only the pump will operate in a specially designed mode and remove excess air from the heating and domestic hot water circuit

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.

Important: it is imperative to connect the input and output node of the second circuit in such a way that the expansion tank is within the circuit. In fact, in this mode the boiler operates like a small-capacity boiler.

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 neither practical nor 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 and 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:

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.

Error F.75

Error f75 of the Vaillant boiler means that after starting the pump five times, the pressure does not rise, but remains below 50 mbar. How to resolve error F75 Vaillant? What to do:

Check the water pressure sensor and pump. Air may have entered the heating system. Check water pressure and expansion tank.

If your Vaillant boiler gives an error, please contact our staff. We will make an accurate diagnosis and... All work is guaranteed!

Error F22 on the display indicates that the water is not heated to the temperature specified in the program. It may arise during the process, and the washing will continue, although it cannot be called high-quality. Most often, the heating problem is critical, so the machine will stop completely.

If your model does not have a display, pay attention to the RPM lights. In the described case, three will light up at once: 1000, 800 and 600 (or 800, 600 and 400), that is, all except one:. If there is no error, other signs may indicate problems with temperature conditions

So, after finishing the program, the laundry is still dirty or smells unpleasant. It is worth noting that sometimes this case is misdiagnosed, believing that the cold laundry you take out of the drum after washing is already a problem. But since rinsing always takes place in cold water, in this case there is no reason to panic

If there is no error, other signs may indicate problems with the temperature regime. So, after finishing the program, the laundry is still dirty or smells unpleasant. It is worth noting that sometimes this case is misdiagnosed, believing that the cold laundry you take out of the drum after washing is already a problem. But since rinsing always takes place in cold water, in this case there is no reason to panic.

Practical recommendations

It is advisable to order and install a new German sensor of a new modification in the Vaillant boiler (article 0020023721). The price is quite high (around 11,500 rubles), but the warranty on it is 5 years, and the problem with the appearance of error f75 due to the “whims” of the flow switch will be solved forever. It is made in such a way that debris is excluded: special membrane material, polymer filling of voids in the sensor body.

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If you have experience and methods on how to fix error f75 of a Vaillant boiler or what needs to be done based on your experience, write in the comments to this article, we will try to consider your option and analyze it in detail in this article or one of the following articles. You can also send photos and videos with comments and descriptions.

List of first level problems

Let’s first consider what the owner can “fight” on his own, without fear of the product becoming completely unsuitable and voiding the warranty.

The list of situations available for correction includes two options:

• The boiler doesn't work at all. Those. the device does not heat the coolant if it is a single-circuit model, and does not heat either the coolant or sanitary water if it is a double-circuit model.
• The boiler heats sanitary water, but does not heat the coolant. This problem is typical only for dual-circuit units.

Both of these positions have a number of completely removable reasons and several solutions that a prudent owner should familiarize himself with. However, before a detailed study of the situation, you should check whether the boiler is connected to the network at all and whether one of the functions is disabled: heating or DHW.

Now let’s look at the typical causes and methods for eliminating them in the case when the boiler does not heat at all:

• The gas valve is closed. Both shut-off devices installed by gas workers on the inlet gas pipe must be opened.
• The supply of cold water is cut off. This can be solved by opening the shut-off valve on the water pipe.
• Power supply disruptions. The heating unit will stop operating if there is no power supply. If the electricity supply is restored, the boiler will start itself.
• Temperature set too low. The owner of the boiler corrects an oversight made when making settings by simply switching the unit to the required temperature regime.
• Water pressure drop (F22). The encoding will indicate a lack of pressure in the system for normal operation of the boiler. Its appearance means that you need to bleed the air from the batteries and open the make-up valve located at the bottom of the device.
• Refusal to ignite (F28). If the third attempt to ignite the gas heating equipment does not lead to the desired result, you need to find the fault reset button on the control panel, press it and hold the position for at least a second. Failure again? Call the gas workers.
• Chimney fault (F48). This signal indicates an increase in the temperature of the exhaust flue gases. They could have stagnated and overheated due to a clogged external chimney that needs to be cleaned.

Note that a drop in pressure will also be signaled by the S76 indicator. This code is from the boiler condition monitoring group. However, to restore operation, the same actions will be required as when fixing error F22.

For the sake of his own safety, health and the safety of his household, the boiler owner is obliged to monitor the smoke removal system. Complete removal of gases is necessary, since the products of blue fuel processing are extremely toxic

The second type of violation, determined by the operation of only the hot water supply without heating the coolant, is most often associated with errors made by the technician during the settings. You can change the temperature yourself. The manual supplied with the boiler describes in detail how to perform this operation.

Basic error codes (f28, f75) and their brief explanation

There are a lot of codes for various errors or malfunctions.

Let's look at the most common of them:

IMPORTANT!

In addition to error codes marked with the letter F, there are status codes marked with the letter S. They inform about the ongoing process and are not errors.

What causes an emergency stop

Chimney

• Clogging of the channel, blocking - this is often associated with error f36 of the Vaillant boiler. Ice on the inner walls and head, a layer of dust, debris, cobwebs on the filter grille - the draft decreases, the heating unit is blocked by an emergency signal.
• Illiterate design, violation of installation rules. The manufacturer gives comprehensive recommendations for arranging a chimney for a Vailant boiler: pipe cross-section, length of route and vertical section, elevation above the roof, slope and a number of others. A discrepancy in one of the parameters has a negative impact on traction and initiates blocking of the unit with error f36. During operation, miscalculations appear when the wind direction changes, strong gusts (draft overturning - the boiler “blows out”), precipitation (liquid overflows from the drainage system into the chimney pipe).
• The condensate collector is not installed in the channel or the location for the storage tank is incorrectly selected.
• The hood is calculated based on the characteristics of the heating unit and power. Owners who, in order to save money, connect Vailant to a chimney previously installed for another boiler often encounter error f36. The manufacturer also warns about possible problems - only the air duct/gas outlet of the Vaillant brand (instructions, section 5.5).

Blown air supply to the vaillant boiler through the external wall

• Violation of tightness. Unreliable knee joints and air leaks worsen traction.
• Damage (lack) of thermal insulation. A drop in temperature reduces the flow rate of volatile combustion products through the channel - the cause of error f36. It can be removed by insulating the chimney.

Adviсe

• There are many recommendations on the Internet for solving the problem with code 36 of the Vailant boiler. Some are useful, and some are simply harmful. Some of the “experts” suggest how to remove error f36: replace the temperature sensor with a response limit of t = 65 with a similar device designed for 95 (the temperature values ​​​​are indicated on the case). Unprofessional intervention in the design of the Vailant boiler is prohibited! We are talking about removing carbon monoxide from the premises. There is no need to explain what its accumulation in the room leads to due to the delay in the thermostat response.
• A decrease in the draft of an atmospheric boiler is caused by an exhaust device operating nearby. It is prohibited to use technical equipment of this category near Atmo series units.

Violation of recommendations for installation of the unit

The instructions set out the requirements for the premises and mounting of the Vailant. Unprofessional installation of the boiler causes error f36.

Causes

• Inconsistency between Vaillant power room dimensions.
• Increased room temperature.
• Insufficient natural ventilation. It’s easy to verify by opening the window and door sashes. Additional air flow will remove error f36.
• Wrong choice of location. A small interval between the Vailant boiler and surfaces (walls, floors, ceilings), household appliances that emit thermal energy (gas stove) leads to overheating of structural elements. Minimum distances are specified in the manual. If they are not met, conditions are created for the temperature sensor to operate, and error f36 is displayed.

Heat exchanger contamination

A layer of dust on the body of the device, in the intercostal space, prevents air from entering the Vaillant boiler from the room. Traction drops, emergency stop with error f36. It can be removed by cleaning the combustion chamber and heat exchanger surface.

Reduced circulation rate

Sensor problem

Other errors indicate a malfunction of the device (AtmoGuard), but the “behavior” of the electronics is unpredictable: anything can happen. Code 36 is caused by a breakdown or incorrect operation of the traction sensor. In Vailant boilers, the chimney control system is “cunningly” designed. The difference from heating installations from other manufacturers is that the removal of volatile combustion products is monitored by 2 sensors. Their precise location in the channel guarantees a quick response to the slightest change in flow.

Vaillant boiler draft sensor

One part of the sensor (sensor) controls the gases escaping into the chimney, the other (external) controls their penetration into the room. If this is observed, the electronics turns off the supply of “blue fuel” to the burner after two minutes. After 15–20 minutes (when the sensor has cooled down), the Vaillant boiler automatically starts working. The heating unit is blocked with error f36 provided that this situation is repeated 2 more times.

The instructions do not contain recommendations for “deep” testing of the sensor. Only the test method for operation is described: close the chimney, start the Vailant boiler. Next, observe the actions of the electronics: emergency shutdown (2 minutes), re-ignition (15–20).

Types of boilers produced

Vaillant produces gas and electrical equipment. Electric boilers are limited to one EloBLOCK model in several power options.

Gas appliances are presented in a more diverse range.

Among them:

• traditional (throw away some of the useful heat along with smoke);
• condensation (use additional energy from exhaust gases);
• single-circuit VU;
• dual-circuit VUW;
• atmospheric Atmo (uses air from the room for combustion, and a standard chimney for exhaust);
• turbocharged Turbo (allows you to arrange an underwater and outlet path through the wall);
• mounted;
• floor

Single-circuit

Boilers with one circuit are designed to heat only the coolant of the heating system. For water treatment, you can connect an external boiler.

In dual-circuit models, water is prepared separately for heating and for domestic household needs.

Wall mounted

Wall mounted boilers are mounted using fasteners on the wall. Save space due to small dimensions. Household installations of low and medium power are manufactured in wall-mounted versions.

Floor-standing

Powerful domestic and industrial boilers are installed permanently on the floor. They have significant weight and dimensions. In some cases, they require a separate room - a boiler room.

How to run self-diagnosis

The self-diagnosis system is a complex of sensors consisting of NTC elements (thermistors) or software products.

All of them operate in continuous mode, monitoring the status of connected elements from the moment the boiler is turned on.

Therefore, the self-diagnosis system does not need to be started - it is always on and operates in constant mode, monitoring the operating mode of components and parts, immediately signaling the occurrence of problems.

In the event of an emergency, a special code will appear on the display indicating the problematic structural element. The user is only required to react appropriately when an error occurs.