European] Vaillant[/anchor] is well known to specialists and users of heating equipment.
Founded more than 100 years ago, the company has accumulated vast production and technological experience and has developed a lot of its own patented components and parts.
Gas boilers manufactured by this company are known far beyond Europe and are exported not only to Russia, but also to most countries of the world.
The units are famous for their reliability and resistance to external loads, and are adapted to the technical conditions of the country where they will be used.
Emerging problems are immediately diagnosed by a system of sensors that send a signal to the display about the occurrence of a particular problem.
Let's take a closer look at this issue.
Popular malfunctions of Vaillant gas boilers
During the operation of equipment, situations constantly arise when one or another component is under increased load and may fail.
A variety of situations can arise, but most of them can be systematized and classified as the most typical. The manufacturer cares about the reliability of its units.
The design of each installation contains a set of special sensors that monitor the condition of certain parts and notify the user when mode failures or failures of a particular element occur . These sensors constitute a self-diagnosis system that sends signals to the electronic control board.
The presence of such a system greatly facilitates the process of localizing a fault that has arisen and allows it to be detected at an early stage. The error code takes precedence over other system messages and is displayed in any situation.
This facilitates repairs and ensures the safety of expensive equipment.
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 f75
Unlike other boilers, the vaillant self-diagnosis system checks whether the circulation pump is running. Since it is able to quantitatively register its change, at the moment the circulation pump is started, the program checks for the presence of a pressure surge of 50 mbar for 20 seconds. The circulation pump is designed to pump coolant through the system, but at the moment of start-up it briefly creates a slight excess pressure. The absence of such a jump can be regarded as a malfunction of the circulation pump, and in order to prevent further overheating of the system and improper operation of the boiler, the automation blocks operation with error F75.
In fact, error F 75 can also be caused by side effects, for example, clogged sensor, air in the heating system, borderline pressure level in the circuit (low, but within the acceptable limit). If the sensor itself is faulty, status codes F73 and F74 are provided (when the voltage at the sensor is too low or too high).
The boilers are also equipped with analog pressure gauges, so for diagnostics, the sensor readings can be compared with the readings on a mechanical pressure gauge. The accuracy of a mechanical pressure gauge is about 0.2 bar.
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 ones:
| Code | Decoding |
| F00 | Supply thermistor circuit open |
| F01 | Open return thermistor circuit |
| F02-03 | Opening the temperature thermistor or storage sensor |
| F04 | Return thermistor break |
| F10 | Supply thermistor short circuit (exceeding 130°) |
| F11, F14 | Short circuit of the return thermistor (exceeding 130°) |
| F22 | Dry running (pump fault) |
| F23 | Lack of water. Determined by the temperature difference between the forward and return lines |
| F27 | Parasitic Flame |
| F28 | Ignition lock |
| F29 | Failure in operating mode (occurs when the flame goes out and the ignition attempt fails) |
| F35 | Error in gas outlet |
| F37 | Unstable or abnormal fan speed |
| F72 | Error in forward and/or return line sensor readings |
| F75 | The pump is unable to raise pressure |
| F76 | Primary heat exchanger overheating |
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.
Vaillant boiler - error f28
Features of operation and diagnostics
During connection, operation and maintenance of the Vaillant heating gas boiler, some malfunctions may occur.
Models that have an electrical control system with a screen make it possible to understand what exactly does not work in a given situation. To understand what to do in certain cases, let’s look at the common error codes for the Vailant gas boiler, and what needs to be done if they occur. If several errors occur at once, they are displayed alternately for approximately 2 seconds.
The icons may begin with the letter F (error) or S (status). Technical characteristics and codes that are specific to each specific model are specified in the operating instructions.
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:
- Gas is not supplied.
- The valve has fallen out.
- No grounding.
- The electrodes are broken.
- 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.
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:
- There is a “reset failure” button.
- Equipment dismantling.
- Carrying out diagnostics.
- 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.
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.
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.
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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.
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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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:
- air abundantly mixed with gas;
- low pressure in the gas pipeline;
- grounding errors;
- broken cables;
- improper connection to the gas pipeline.
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.
Sometimes the boiler hums when turned on - there is no need to be afraid to open it. You need to make sure that no tubes or other parts are in contact with the body. Then there will definitely be no problems with extraneous noise.
You should also check the following reasons:
- saturation of pipes with air;
- oxygen content in water;
- the appearance of scale;
- Difficulties in fan operation.
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:
- turn off the boiler, supply and return valves;
- open the drain fitting until it is completely drained;
- connect the pump unit via a spool, under no circumstances blocking the fitting.
Any type of pump is useful for the job; You can take a car gauge and a pressure gauge from the car too. The air pump is pumped until water flows out of the outlet fitting. Next, release the air and repeat its introduction, continuously monitoring the pressure gauge readings. It should show 1.1–1.3 bar; more precise information is provided in the technical documentation. Now you can close the pouring fitting, open all the previously closed taps, feed the boiler in the normal way to 1.2–1.5 bar, and then start warming up.
It is especially important to monitor internal pressure if the house or other structure is visited only periodically. It is no secret that the stability of power supply is now far from ideal. And if the power stops, the boiler stops working, so the pressure inside the tank can drop due to cooling below what is required for the boiler to operate. Even after the power supply is restored, the boiler cannot warm up the house, because soon the uncontrolled house presents a sad sight - pipes and radiators torn from ice everywhere. Therefore, the pressure in the expansion tank must be constantly monitored. No less bad is the situation in which the pressure level continuously increases. Of course, a well-chosen and correctly installed safety valve corrects the matter to some extent, but it is better not to rely on it, since this is still more of an emergency measure. It is always worth remembering that pressure control deserves increased attention.
Malfunctions and how to fix them
The appearance of one or another error on the display does not mean that serious problems have arisen. Electronics sometimes perceive sensor readings as signals about the failure or breakdown of a particular component. Therefore, usually the first action is to reset the error and restart the boiler.
If the error appears repeatedly several times in a row, there is no longer any doubt about the malfunction.
Let's look at ways to solve the most common problems:
F 22
The lack of water may indicate that the pump has stopped (check the contacts or condition of the wire, replace the pump), problems with the feed tap or with the sensor itself.
F 28
Ignition blockage occurs due to the lack of a positive result when the device attempts to ignite the gas on the burner. The most likely reason is failure of gas fittings, lack of gas in the pipeline, air entering the gas pipeline and other problems with the gas supply system.
F 29
The reason for the cessation of gas combustion is most often the cessation of supply from the gas pipeline, the recirculation of exhaust gases, which reduce the ability of the gas to ignite, or the failure of the ignition transformer. Alternatively, you should check the condition of the ground electrode.
F 36
This error occurs only on boilers with an atmospheric burner and indicates that exhaust gases have entered the living room atmosphere. The predominant reasons are poor condition of the chimney, lack of draft (reverse draft due to external conditions), too short chimney pipe . Often the reasons are too high a room temperature or a small distance from the walls made during installation of the unit.
F 75
After 5 attempts, the pressure in the system does not rise. The cause may be either the presence of air in the pipelines or pump failure . Alternatively, the expansion tank may be mistakenly connected to the supply pipeline or the overall water pressure in the main line may be weak.
Gas boiler Vailant: operating instructions
At the same time, double-circuit boilers do not operate in heating and water heating modes. By default they work for heating. But when the hot water tap opens, the boiler switches to heating mode. It is worth knowing that water is heated in limited quantities - for domestic needs. The boiler switches to heating mode automatically after the hot water tap is closed.
Experts strongly do not recommend installing a double-circuit wall-mounted gas boiler Vailant yourself. Errors in installation will lead to the fact that it will not meet your expectations. Most of the complaints made by users are based on improper operation and errors during installation. Problems can occur due to poor quality of gas and energy supply, which is not uncommon in our country.
If you are using a Vailant gas boiler, the instructions for it are very simple and understandable; each malfunction or malfunction is indicated by a specific code that is displayed on the control panel monitor. Some problems can be fixed on your own, while others will require calling a professional.
Boiler Vailant error f75
This error code occurs if, after starting the pump 5 times, a pressure increase of >50 mbar does not occur. There may be several reasons for this error:
- The heating system is filled with air.
- The water pressure sensor has failed.
- The pump is faulty.
- Boiler has low water pressure
- An expansion tank is connected to the supply line.
Some reasons can be eliminated yourself by reading the instructions. But some can only be handled by a master.
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.
Pressure is rising
An increase in pressure can be caused by an open make-up tap. This can be determined simply - continuous replenishment sharply reduces the possibility of heating the coolant, causing the outlet temperature to decrease.
At the same time, the valve should operate, releasing excess heating agent pressure into the sewer system . It is possible for the heating agent to boil in the heat exchanger, which also causes an avalanche-like increase in pressure due to a sharp expansion of volume.
Alternatively, the control board may have failed. The issue can be resolved by resetting to the settings made at the factory during manufacture.
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.
How to fix error f22 of a Vaillant gas boiler (Vailant)
Modern heating installations eliminate the need for the user to contact a service organization if a problem occurs after the warranty expires, wasting time and wasting money. The reasons causing error f22 of the Vaillant boiler can be eliminated independently. The article tells you what to do in this situation.
