Boiler "Vailant": error f28, diagnosis and remedies

The German company Vaillant is famous as a manufacturer of energy-saving and durable heating equipment. Consumers in more than 60 countries around the world choose the Vailant boiler for heating and hot water preparation; error f28 (or any other) is the result of self-diagnosis of the unit, helping to understand where to look for a breakdown. Let's figure out what causes the error and how to correct the problem.

Compact wall-mounted model Vaillant Source proffinstal.ru

Vaillant error F28: what is it?

If you look at the instructions, there is information about this error, but it is difficult to give an exact definition. The malfunction is related to the gas burner. What happened to her needs to be examined individually.

Probable reasons:

1. Gas is not supplied.
2. The valve has fallen out.
3. No grounding.
4. The electrodes are broken.
5. The electronic board is outdated.

The error is common and most often indicates a problem with the valve. This is the weak point of boilers; they have a certain operating life. If the equipment, for example, has been used for more than five years, then you should not be surprised.

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

Boiler inspection and maintenance

Gas boiler maintenance is recommended annually. Basically, maintenance comes down to visual inspection and preventive cleaning of the main components: heat exchangers, combustion chamber, coarse filters and the condition of the expansion tank.

The outside of the primary heat exchanger is cleaned of soot with a soft brush. Under no circumstances should you use brushes with metal bristles, because... The copper plates are treated with a special anti-corrosion coating and its damage will lead to a serious reduction in service life. Due to their design features, primary heat exchangers from the inside in most cases cannot be washed; their service life can be seriously reduced by the use of antifreeze or frequent replenishment with high-hardness tap water.

The secondary heat exchanger (DHW), due to the constant flow of water through it, is more susceptible to the formation of deposits and scale, but it can be successfully washed at regular intervals. Heat exchangers are washed with special installations (boosters) using special equipment. The process involves long-term (sometimes up to several hours) pumping of chemicals that help dissolve and wash away scale. Valiant recommends washing with regular acetic acid.

The expansion tank is designed to compensate for the thermal expansion of the heating system and is also subject to annual maintenance. It consists of measuring its pressure. The measurement must be taken on an empty boiler and, if necessary, pumped up to the static pressure of the system (approximately 1-1.2 bar). If water comes out of the control fitting, this indicates that the tank membrane is not sealed and needs to be replaced.

It is necessary to wash and clean heat exchangers in a timely manner, because dirt and scale deposits reduce thermal conductivity and flow area, which leads to a decrease in the efficiency of the boiler and overheating, and subsequently an expensive replacement.

It is recommended to set the hot water supply temperature so as not to dilute it with cold water, thereby ensuring minimal heating. The lower the temperature of the hot water, the lower the intensity of scale formation.

Coarse filters are meshes, so their maintenance is reduced to removing and rinsing under running water to the desired condition.

Over time, a gas burner can become clogged and coated with combustion products; cleaning it, as a rule, can be easily done with a soft brush and a vacuum cleaner. If there is severe contamination, it can be easily removed.

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).

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.

Typical errors

Knowing the error codes of the Vailant boiler, you can diagnose almost any malfunction. And having experience in repairing heating equipment, nothing prevents you from dealing with the breakdown yourself. The codes are displayed on digital indicators, representing two-digit numbers with the letter F. Let's look at them in more detail.

F5

Error F5 means a break in the external exhaust gas sensor. Possible reasons may be incorrect operation of the exhaust gas sensor, the plug is removed or the cable is damaged, or the spare resistor is installed incorrectly. The code is valid only for the mounted model Vailant Atmo.

5ER

If the display alternates between the water temperature and the 5ER (or SER) error, this is a reminder that it is time to service the device.

The user can set the frequency of how often this reminder pops up. The value is set in diagnostic item D.084 within the range from 0 to 3000 hours with an interval of 10 hours (the number 300 corresponds to 3000 hours). To completely disable this function, enter the symbol “—“ instead of the numeric value.

Code F61

Serious error related to the operation of the gas valves. Indicates their malfunction and the breakdown of the electronic board. In rare cases, the code is displayed when the connecting wires are broken.

F20

Error F20 (F20) indicates that a protective shutdown of the device has occurred due to the fact that the STB temperature limiter has tripped. It is triggered when the maximum permissible temperature is exceeded.

This can happen due to the fact that the ground contacts of the wiring harness with the housing are incorrect, or the NTC of the return or supply line is broken (weak contact). A breakdown through the ignition wire, electrode or ignition plug is also possible.

F21

Error F21 means an emergency shutdown of the GFA flame control machine.

F22

Error F22 (F22) indicates that a protective shutdown has occurred due to insufficient water. The reasons for this are a malfunction of the pump cable or toggle switch, insufficient water, the pump does not work or is blocked, or its power is too low.

Error F32

Characteristic exclusively for Vailant condensing boilers. Diagnoses a malfunction of the fan responsible for removing combustion products. In this case, check the fan and connecting wires. Sometimes the culprit is the electronic board that controls the equipment.

Errors F35 and F36

When these codes appear, open the windows and ventilate the room, check for any foreign odors. It is quite possible that combustion products go directly into the room instead of the chimney. Codes are also displayed on the display if the flow of fresh air is disrupted. The situation is typical exclusively for Vailant atmospheric boilers.

Code F39 is not found in Vailant heating boilers - it is typical for Ferroli boilers, indicating problems with the outside temperature sensor.

F23

Error F23 detects an emergency shutdown due to too large a temperature difference between sensors located on the supply and discharge lines.

This happens for the following reasons:

• Very low pump power, why pressure drops on one side;
• the pump is blocked;
• The return and forward line NTC sensors are not in the right places.

Error F.28

Does the Vaillant boiler give error f28? This means that there are some problems with ignition during startup.

How to fix Vaillant boiler error f28 and what to do first:

• Check the serviceability of gas fittings; • Check the gas meter and gas pressure switch. The pressure may be too low. • Check the boiler grounding. • Check the electronic board. Perhaps the problem is its malfunction.

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Error F.11

Error F.11 means a short circuit in the return temperature sensor.

What to do:

• Check the sensor plug • Check the sensor itself

F24

Error F24 signals an emergency shutdown if the temperature rises too sharply. This means the presence of air in the device, reduced pump performance, blockage, or very low pressure in the heating system. The gravity valve may be incorrectly connected or blocked.

F26

Error F26 means that the flow of the stepper motor gas valve is not detected due to a breakdown of the gas fittings. Perhaps the servomotor of the gas valve is not connected or broken, the connector is incorrectly inserted into the board, or there is a break in the wiring harness.

Error F.67

Error F.67 indicates that the input signal to the flame control device has exceeded the limits (from 0 to 5V)

How to fix error F.67:

• Check the serviceability of the electronics

Error F75

Another common sign of breakdown. Error F75 in Vailant boilers indicates problems with pressure in the heating system. It occurs after starting the circulation pump . Usually in this case the pressure rises by about 0.2-0.4 atmospheres. If this does not happen, the problem may lie in improper installation of the system. First, you need to check the functionality and correct connection of the expansion tank (expansomat), and then de-air the circuit.

After this, we check the functionality of the pump - it should drive the coolant along the circuit. A faulty pump must be replaced; they are usually not repaired.

Code F62

The boiler “sees” the flame for longer than four seconds after closing the gas valve. Possible reasons:

• The valve is broken - it needs to be repaired, or better yet completely replaced (it can lead to leakage).
• The burner needs to be cleaned.
• There is a malfunction in the system board - we reboot or test it at the nearest Vailant service.

Please pay special attention to this error.

Error F.70

Error F.70 indicates that the Vaillant boiler version numbers for the display and electronics are different. This happens when the display and electronics are replaced at the same time, and the boiler version number is not re-entered.

How to fix error F.70:

• Enter the boiler version number again for the display and electronics.

Error F.71

Error F.71 means that while the boiler is operating, the readings of the supply line sensor do not change.

How to fix error F.71:

• Check the serviceability of the electronics

Error F.72

Error F.72 indicates that the supply or return line sensor reading is incorrect

How to fix error F.72:

• Check the serviceability of the flow and return line sensor

Error F.27

Error f27 Vaillant means that a flame signal is received despite the closing of the magnetic gas valves.

What to do:

• Check the serviceability of the flame control device • Check the serviceability of the magnetic gas valves

Error F.74

Error F.74 indicates that the water pressure sensor signal is (too high). The water pressure in the system is more than 4.5 bar. Most likely, the signal is incorrect and this is an internal error in the water pressure sensor.

How to fix error F.74:

• Check the serviceability of the water pressure sensor

Errors F0, F1, F2, F3 and F4

The first two occur in Vailant heating boilers if the coolant temperature sensor (NTC sensor) fails. It must be replaced with a sensor of a similar model. Despite the absence of vibrations, the connecting conductors may also fail - check their integrity with a multimeter. You should also evaluate the quality of the connections, inspect the connecting plugs - codes often appear due to oxidation of the contacts. Codes F2, F3 and F4 are caused by the accumulator sensor.

Errors F5 and F6 (and F15 and F16)

This code is typical for Vailant Atmo series boilers with atmospheric burners. It indicates a breakdown of the traction sensor or a break in the connecting wires. We recommend checking the integrity of the conductors and testing the sensor itself. If a breakdown occurs after disassembling and reassembling the equipment, we check that all connections are correct. In turbocharged units, codes F15 and F16 occur.

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.

Codes F10 and F11

Their appearance means a short circuit in the supply and return temperature sensor circuits. Not only the wires need to be checked, but also the temperature sensors themselves. We test detachable connections in the same way.

Error F25

In Vailant boilers, it indicates that the temperature of the combustion products in the chimney is too high. When overheating is detected, the equipment turns off. If the gas equipment and heat exchanger are working properly, we test the sensors and electrical connections.

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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.

Gas path diagnostics

When connecting a building to a main pipe

If we are talking about a residential building, and “blue fuel” is chosen as the main energy resource, in the house, in addition to Vaillant, there is a gas stove. After the pipes have been laid, there are no devices in the section of the circuit up to the boiler. Therefore, you can control the flow of gas without leaving the kitchen.

The check comes down to igniting all the burners on the stove at maximum mode. Flames with a characteristic shade will indicate the absence of problems with the fuel supply, and their intensity and stability will indicate the constancy of the pressure and its normal value. If the stove does not light up or does not work correctly, you need to look for a fault in the section between the main line and the place where the gas pipes are laid (the method is described below).

With autonomous gas supply

Check what

• Shut-off valve. If the Vailant boiler is taken out of service at the end of the heating season, the owner of the property, as a rule, blocks the main line and then forgets about it. Perhaps it is the gas valve that is causing the f28 Vaillant error.
• Shut-off valve. Triggered when the voltage is turned off; A “normally closed” type device is installed on the gas pipeline. It must be moved to the working position manually.
• Gearbox. Insufficient insulation of the head of a gas tank or an outdoor cabinet with a cylinder group causes icing of this device - the pipeline is blocked. Contamination of the channel is reflected in the pressure - when its value is below the response threshold of the gas valve of the Vaillant boiler, error f28 appears.
• Filling the tank. As the “blue fuel” is consumed, the pressure in the pipe also gradually drops. The most typical case of error f28. The igniter fires, the Vailant boiler starts, but the burner goes out. And so several times, as if she was missing something. Namely, normal gas flow.

Another option is the formation of an ice jam on one of the sections of the highway outside the building. But this defect must be dealt with (and eliminated) by specialists.

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.

Installation recommendations

The Vailant gas boiler may issue error F28 due to incorrect installation of the unit. Therefore, the installation of the device must be coordinated with the gas distribution company.

It is also necessary to correctly determine which hole in the wall the chimney will go through. Some parts of the home's structure may be too strong and thick for this type of equipment.

When connecting the boiler for the first time, it is necessary to use a voltage stabilizer. It is important to pay attention to the polarity.

In order not to encounter the fact that the Vailant boiler displays error F28, it is necessary to make the connection correctly. You need to understand that only professional specialists will be able to carry out this procedure in accordance with all requirements.

If the installation is carried out independently, then it is necessary to draw up a design for the heating system and have it certified by the relevant authorities. Do-it-yourself or poor-quality installation can cause serious problems.

Diagnostics and boiler failures

It should be noted that Vaillant equipment is one of the safest among all others. The number of settings, parameters, and checks here is significantly greater than in boilers of other brands. Boilers with displays can display status codes, diagnostics (two levels), faults and setup programs. The average user will only be interested in error codes, so everything else is mainly intended for service specialists.

The Vailant automation also stores a history of all errors, this makes it very convenient to diagnose and troubleshoot the boiler. At any time you can view the last 10 errors that occurred on the boiler (use the “info” and “-” buttons to display the list).

Next, we will consider the most common errors of Vaillant boilers and recommendations for eliminating them.

What checks are carried out before the first start-up of the boiler?

For further normal and safe operation, as well as maintaining the warranty, any equipment requires compliance with a number of conditions:

• voltage in the network according to the PUE standards and mandatory grounding of the boiler (ideally there should be no potential between zero and “ground”, Vaillant allows no more than 1.5 Volts)
• compliance of the system as a whole with the power of the installed equipment (lack of heating or hot water capacity prohibits start-up). Constant operation of the boiler at maximum power will quickly lead to failure of the unit.
• checking compliance with chimney installation standards (for atmospheric boilers, presence of draft, for coaxial chimneys, pipe extension and slope towards the street)

The installation manual also requires installing a coarse filter on the cold water supply to the boiler and on the return pipe of the heating system, as well as a gas filter.

It is better to study the commissioning process in more detail in the instructions for a specific boiler model.

The selection of the test program (airing, filling the system) is started by turning on the boiler and simultaneously holding the “+” button for 5 seconds. The selected program is activated with the “i” button. For TEC series boilers, five programs are preinstalled.

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.

Useful tips

In order not to rack your brains over how to resolve error F28 in the Vailant gas boiler, you must carefully study the instructions before starting to operate the device. It is quite simple and intuitive even for a novice user. Additionally, the device is equipped with a special display, which displays all codes with the name of certain problems.

If any error occurs, you must check its number and read the annotation in the instructions. Some of the problems can be fixed on your own, but in most cases only specialized assistance may be required. To avoid troubles, before each heating season, it is recommended to call a technician who can check the boiler for leaks, as well as for proper performance.

Incorrect pressure in the unit is the most common cause of error F28 in the Vailant gas boiler. What to do in this situation? First of all, experts recommend maintaining the pressure level on the middle gray strip of the sensor. If the arrow moves into the red zone, this indicates that the indicator is decreasing very much. This can seriously affect the operation of the system.

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.

Download instructions

Download instructions for Vaillant boilers.

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 completely protect itself.

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.

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.

Vaillant boiler: error F28

If we talk about this code, it can indicate several malfunctions at once. For example, the cause of this phenomenon may be a breakdown of the gearbox, which is responsible for gas pressure. The meter could also be faulty.

In some situations, the Vailant gas boiler generates error F28 when the gas is oversaturated with air. It is also necessary to monitor your blood pressure. To change these values, you must check the settings yourself.

Some users accidentally close the gas valve, which can also cause an error. In addition, the cable often breaks. The gas magnet can also fail. Additionally, you need to check the ignition transformer and make sure that there is no carbon deposits inside the system.

Most rarely, this error occurs when there is a breakdown in the control board. Therefore, regardless of whether the 24 kW Vailant boiler or another model produces error F28, it is recommended to check some components and make sure that the unit is being operated in the correct mode.

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.

Vaillant boiler error f28 what to do?

This error can occur either randomly or require the intervention of a service technician. Error f28 occurs when unsuccessful attempts are made to ignite the gas burner.

What could be the reasons for error f28 of the Vaillant boiler:

• no gas is supplied to the burner
• low gas pressure at the gas valve outlet
• gas valve is faulty
• problem with the ignition electrodes and the flame presence electrode
• incorrect grounding of the boiler
• malfunction of the electronic board (repair of the boiler board is possible)

To begin with, you can use the Failure Reset button (flame with a cross). Perhaps the ignition failure was accidental and the boiler’s operation is returning to normal.

If error f28 appears again, we recommend calling a service technician because further checks will require special equipment and knowledge. It is not recommended to disassemble the gas valve yourself.

You can check the integrity of the wires coming from the electrodes to the control board and, during the next start-up attempt, check visually that the electric spark strikes the burner body and not somewhere else.

Service specialists check the reliability of the boiler grounding and the serviceability of the electrodes, as well as the pressure at the outlet of the gas valve. If all components are normal and there are no violations, then diagnostics of the electronic board will most likely be required.

There is no need to change the control board right away. In most cases, it can be successfully repaired. Repairs will cost significantly less.

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.

Adjustment features

Boilers from this manufacturer are easy to control. However, this does not mean that every person can cope with such a task on their own. It is best to make adjustments together, when one person turns the tap and the other monitors the position of the pressure arrow. To adjust the water or heating temperature, you can use special valves located on the control panel. In this case, how hot the water is will be displayed on the display. Thanks to this, you can increase or decrease the temperature by turning the tap to the desired position.

Also, the fact that the time has come to figure out how to eliminate error F28 in the Vailant boiler can be signaled by special light sensors on the device panel. The green light comes on when heated water is being used. A yellow indicator indicates that gas is burning. If the red LED lights up, this indicates a problem with the system. It is also worth paying attention that only water is poured into the boiler. There is no point in doing experiments.

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.

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

Prevention

Like any other equipment, the boiler requires timely prevention.

Cleaning the boiler

Cleaning of soot from the boiler is carried out with a soft brush from the outside. The use of harsh cleaning is unacceptable, since the boiler plates are made of copper, with an anti-corrosion coating that cannot be removed. The disadvantage of the heat exchanger design is that it cannot be internally washed, and the use of antifreeze or feeding the circuit with hard water shortens the service life of the unit.

We recommend: What is a gas tank and why is it needed in a country house?

Fighting deposits and scale

The problem of deposits is even more important when operating secondary hot water boilers, due to the constant circulation of hard water through its circuit. This means that it becomes even more clogged with deposits and scale. The manufacturer took care of this situation and created conditions for periodic washing of the heating surfaces of the DHW circuit. This can be done using a booster with the addition of special agents to the circulation coolant.

Next, the solution is run for several hours, dissolving and washing away the scale.

Note! In addition, it is recommended to maintain a low temperature for hot water supply, which does not require dilution with cold water. In this case, the intensity of scale formation, which begins at 60 °C, will be practically reduced to zero.

Expansion tank maintenance

Expansion tanks are subject to annual maintenance. To do this, the boiler is filled with water to the operating level in the system of 1–1.2 bar. If water appears from the control output of the expander, then the tightness of the tank membrane is broken and it will need to be replaced.

Burner and filters

The filters on the gas line are made in the form of a mesh; for maintenance they are removed and washed with water. The gas burner also becomes clogged with combustion products over time; it should be cleaned with a soft bristle brush and a vacuum cleaner.

Pressure check

This is another procedure that you can perform yourself if a problem occurs. In order to check the pressure, it is necessary to remove the unit casing. After this, you need to fold back the junction box and close the gas shut-off valve. The next step is to loosen the sealing screw located on the gas valve. After this, a digital pressure gauge is connected. Next, you can open the gas shut-off valve and put the device into operation. After this, the pressure is measured. If these manipulations do not help, then you can try other methods.

Checking and setting the minimum amount of gas

Particular care must be taken during the initial connection and commissioning of gas equipment. To check the minimum amount of gas and avoid subsequent errors, you need to perform several simple manipulations:

• turn off the boiler;
• loosen the sealing screw located on the gas valve;
• connect the pressure gauge;
• press the button with the plus symbol on the display and, while holding it, set the assignment switch “i”;
• continue to hold “+” until the value “P.0” appears on the device screen;
• press the button with the “+” sign again and wait for “P.2” to appear;
• press the “i” button and start the automatic diagnostic system, then the boiler can be switched to the minimum gas supply;
• press the “i” button and wait for a digital value from 0 to 99 to appear;
• Press the “+” or minus button several times until the pressure is set to the correct value.
• To save the changes made, to do this you need to hold down the “i” button for about 5 seconds.

In this case, the unit will automatically exit the diagnostic mode. After this, you can turn off the device, remove the pressure gauge and reinstall the sealing screw.

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.

Checking the functioning of the boiler

And after the unit has been installed, it is also necessary to perform several manipulations to ensure that the performance of the unit is at the required level. To do this, you need to connect the device and check the gas supply lines, heating installations and other pipelines for leaks.

You also need to make sure that the burner flame indicators are in the correct position.

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.

Briefly about the main thing

When operating Vaillant boiler equipment, malfunctions sometimes occur, which the unit signals by the appearance of an error on the screen. The instructions will help you find out whether the signal indicates a minor failure or a serious breakdown. Some problems can be solved on your own. You should start by rebooting the boiler, since the cause of the message is often a system failure.

If rebooting does not help, pay attention to the external sign of the problem. They may be unusually loud noise when the boiler is operating, or low temperature of hot water. Overheating of the system causes an emergency stop; pressure surges indicate leaks. Sometimes a Vaillant gas boiler produces errors (for example, f8) due to improper operation.