How to fix error f75 of a Vaillant gas boiler (Vailant)

Under the Vailant brand, several modifications of gas heating systems are produced, differing in design, operating principle, and installation method.

Error f75, typical for all versions, is rarely caused by a breakdown of the Vaillant boiler - German equipment is famous for its reliability.

Mostly, the reasons for the appearance of a fault code are external factors, but in any case, you can restore the unit’s functionality yourself.

1. Indication of the current filling pressure of the heating system, heating flow temperature or indication of a status code or error.2. Green indicator lamp for hot water is off: No hot water is being drawn up. Flashing: Hot water is being drawn off.3. The yellow indicator lamp lights up continuously: Burner on.

4. Red indicator lamp lights up continuously: The device is in a fault state and an error code is displayed.

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, the same table shows codes f73 and f74. 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.

Water pressure acts on the sensor membrane, which changes stroke when the pressure changes.

The peculiarity of the Vaillant electronic circuit is that it not only controls the operation of the pump, but also the moment it reaches 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.

First steps

Reset.
This is done with a button on the Vaillant boiler panel or by turning off/on the power. Error f75 caused by power surge disappears.

Vaillant TEC pro-turbo8 boiler controls. “Troubleshooting” button to reset certain faults.

Heating circuit recharge.
When the pressure in the system is below a critical value, fault code f22 is displayed. But if the coolant level is “on the verge” (minimum permissible), there will not be a difference of 50 bar when the pump starts working. Therefore, error f75 will appear.
Bleeding air
. When bubbles accumulate in the coolant, the channel is not blocked, but the circulation speed decreases. This affects the correct operation of the flow switch, which issues a corresponding signal to the electronic board. And now it generates error f75 and stops the Vaillant boiler. Models of the TEC series are equipped with a special deaeration program (P.0): after its start, the fault code disappears.

Bypass valve

Its task is to protect the circulation pump mechanism from powerful hydraulic shocks. The valve has a spring, and in case of contamination it does not completely close the channel (half-open position). When the pump starts operating, the relay does not respond to a surge in pressure, which leads to error f75 Vaillant. There may also be deposits in the bypass itself: check, rinse.

Vaillant bypass valve

Expansion tank

Few people associate the correct operation of this device with error f75. But if the special tank is periodically not properly maintained, the pressure in the air chamber is below normal, it becomes one of the reasons for the appearance of such a fault code.

Rubber rubber gradually loses its elasticity, and deposits deposited from the system accumulate in the container body. The direct connection of the expansion tank with the hydraulic circuit of the boiler leads to the fact that part of the dirt gets into the Vaillant, to the pump.

The device of a closed expansion tank

Advice

When servicing, the tank must be dismantled after draining the coolant from the system. If the membrane is replaceable, its suitability for further use is assessed and a decision is made. The vessel itself is thoroughly washed, air (or nitrogen) is pumped into it (after installing the flask), and only then the device is connected to the heating system.

Strainer

Vaillant boilers have a miniature cleaning element installed in front of the pressure sensor to protect its cavity from sediment. During maintenance, it must be changed annually, like any consumable. Gradual contamination of the mesh leads to the fact that the sensor does not respond to changes in pressure in the pipe, and the automation periodically issues error f75.

Vaillant boiler strainer

Pump

Vaillant circulation pump

To accurately diagnose the condition, it should be removed from the Vaillant boiler. Error f75 indicates no shaft rotation or low speed. The result is the same - there is no coolant circulation or it is weak, and the sensor does not detect this. Testing the pump is quite simple.

Electrical part

Vaillant circulation pump wires are damaged

Presence of voltage at the terminals. If it is not there, you need to assess the condition of the lamellas and wires: breaks, oxidation, short circuits.
Under the cover there is a capacitor of 2 or 2.6 microfarads (check the value according to the inscription on the case). It provides the starting current. “Breakdown” or loss of capacity is one of the causes of error f75 Vaillant (the boiler pump will not start). A characteristic hum will be heard (when voltage is applied to the motor), but the shaft will remain in a static position.
Winding problem. To determine integrity, you need to measure its resistance: the norm is 275 Ohms. The ∞ symbol on the multimeter display indicates a break, when the deviation from the nominal value is downward (R

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 experimenting

Common mistakes of Vailant gas heating boilers

Gas autonomous heating systems are the most common and optimal from an ergonomic point of view today. But due to not the best operating conditions, they are often subject to various breakdowns, regardless of the country of origin and the price of the unit.

For example, a Vaillant boiler, the malfunctions of which are often associated with poor gas purification, may not last even one season, although it costs a lot of money. And this is not the fault of the manufacturers, because the equipment is designed for optimal conditions and cannot always effectively deal with problems arising due to the fault of public utilities.

Features of operation

Particular attention should be paid to the gas burner, since it is the one that clogs most often, which leads to the inability to fully control the flame level. Carbon deposits must be removed from the internal surfaces of the working chambers. When using gas, there will be little of it, so the user will not experience any particular difficulties. It is very important to maintain the chimney so that it fully copes with its functions.

Malfunctions of the Vailant double-circuit gas boiler differ from the single-circuit model due to its more complex design. The device simultaneously acts in two capacities, so it has a double load. Let's face it, if the boiler operates only during the heating season, then the water heater has to work all year round without breaks. But it is still necessary to allocate one day during which the system will be turned off and receive appropriate service.

It is better to do this in a timely manner and save yourself from problems that may occur at the most inopportune moment. The most common problem with this category of heating equipment is water leakage at the joints. Therefore, you need to pay special attention to sealing and use the most modern means for this. The connection must be reliable in order to serve for many years and not create any problems for the owners.

Common Mistakes

It is also a fairly common problem when exhaust gases are not completely released into the atmosphere. A smoke exhauster can be of great help here, as it can even correct a not entirely correct chimney installation. The gas burner also needs to be cleaned at least once a year, and more often on the water heating circuit. To resolve more serious issues, it is better to contact the service center.

Every modern boiler is equipped with an automatic system that monitors the status of all systems and, in the event of emergency situations, quickly stops gas leaks. Therefore, there is no need to worry that an explosive concentration may occur if the boiler breaks down when no one is home.

However, it is also worth considering that the computerized control unit operates on electricity, so it is necessary to ensure an uninterrupted supply of voltage to it so that all systems continue to function as normal. For this purpose, UPSs with different battery capacities are used. It would not be superfluous to install a voltage stabilizer.

Decoding the main error codes

1. Error f20 on a Vaillant boiler is quite rare and indicates overheating of the equipment. This may be a consequence of the heat exchanger being clogged with various debris, as a result of which the coolant is not able to circulate fully and is heated to a critical temperature.
2. Error f22 is much more common. It means insufficient water in the system or its complete absence.
3. Error f28 of the Vaillant boiler - the electronic board burned out. This can happen as a result of a sudden voltage surge, which is why a stabilizer is needed.
4. Error f29 of the Vaillant gas boiler - the gas burner does not light up. After three unsuccessful ignition attempts, the boiler automatically turns off. There can be quite a few reasons, from insufficient gas pressure to a stuck valve or clogging of the holes with various debris. You will have to carry out diagnostics yourself, since automation only gives a general idea of the problem.
5. Vaillant boiler error f36 - release of gaseous combustion products into the room. It may occur as a result of a leak in the pipeline or insufficient draft in the chimney. The solution is described above.
6. Error f75 on the Vaillant boiler means a lack of water pressure in the pipeline. The solution method is described a few paragraphs above.

A list of other errors with decoding can be read in the instructions that come with each model.

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Source: https://promplace.ru/kotly-otopleniya/kotel-vailant-neispravnosti-1929.htm

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 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.

Error f 75 in a Vaillant gas boiler - How to fix error f75 in a Vaillant gas boiler (Vailant)

alexxlab05.12.2017
: 0

Vaillant gas heating systems are available in various versions. The most popular are wall-mounted double-circuit boilers Vailant VUW of three series: Turbo FIT, TEC Plus and Pro.

Vaillant ecoTECplus control panel
Vaillant ecoTECpro control panel
Vaillant turboFIT control panel

An analysis of the error tables in their instructions shows the identity of the problems that arise, and for the last two models the instructions are common. The article will help you understand the reasons for incorrect operation or stopping of equipment due to an emergency signal and give recommendations for eliminating them.

Vaillant boiler error f75 Leave

Under the Vailant brand, several modifications of gas heating systems are produced, differing in design, operating principle, and installation method.

Error f75, typical for all versions, is rarely caused by a breakdown of the Vaillant boiler - German equipment is famous for its reliability.

Mostly, the reasons for the appearance of a fault code are external factors, but in any case, you can restore the unit’s functionality yourself.

1. Display of the current filling pressure of the heating system, heating flow temperature or display of a status code or error. 2. Green indicator lamp for hot water is off: No hot water is being collected. Flashing: Hot water is being collected. 3. Yellow indicator lamp lights up continuously: Burner on.

4. Red indicator lamp lights up continuously: The device is in a fault state and an error code is displayed.

Error interpretation

Water pressure acts on the sensor membrane, which changes stroke when the pressure changes.

First steps

Reset. This is done with a button on the Vaillant boiler panel or by turning off/on the power. Error f75 caused by power surge disappears.

Control elements of the Vaillant TEC pro-turbo 8 . Button “Reset faults” to reset certain faults.

Heating circuit recharge. When the pressure in the system is below a critical value, fault code f22 is displayed.
But if the coolant level is “on the verge” (minimum permissible), there will not be a difference of 50 bar when the pump starts working. Therefore, error f75 will appear.
Bleeding air .
When bubbles accumulate in the coolant, the channel is not blocked, but the circulation speed decreases. This affects the correct operation of the flow switch, which issues a corresponding signal to the electronic board. And now it generates error f75 and stops the Vaillant boiler. Models of the TEC series are equipped with a special deaeration program (P.0): after its start, the fault code disappears.

Bypass valve

Vaillant bypass valve

Expansion tank

The device of a closed expansion tank

Advice

Strainer

Vaillant boiler strainer

Pump

Vaillant circulation pump

Electrical part

Vaillant circulation pump wires are damaged

Presence of voltage at the terminals. If it is not there, you need to assess the condition of the lamellas and wires: breaks, oxidation, short circuits.
Under the cover there is a capacitor of 2 or 2.6 microfarads (check the value according to the inscription on the case). It provides the starting current. “Breakdown” or loss of capacity is one of the causes of error f75 Vaillant (the boiler pump will not start). A characteristic hum will be heard (when voltage is applied to the motor), but the shaft will remain in a static position.
Winding problem. To determine integrity, you need to measure its resistance: the norm is 275 Ohms. The ∞ symbol on the multimeter display indicates a break, when the deviation from the nominal value is downward (R

Source: https://fixbroken.ru/oshibka-f75-kotla-vaillant/

Practical recommendations

The Vaillant boiler should not be connected to the network directly, but through a UPS. A unit is a complex device consisting of a group of batteries, their charging and voltage stabilization circuits. Even if the power line is disconnected or the backup electric generator breaks down, the heating installation will continue to function for several hours (depending on the total battery capacity).

The “weak link” of the pressure sensors of any imported boiler, and Vaillant is no exception, is the sensitive element (membrane). Foreign developers focus on their customers, without taking into account our specifics. This concerns the quality of the water filling the heating circuit. Over time, with increased rigidity of the coolant, the rubber rubber becomes “oaky” and loses sensitivity to changes in the pressure of the circulating liquid. In fact, the sensor (flow switch) is working, but boiler error f75 appears periodically. The reason is that the membrane does not respond to slight changes in pressure.

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.

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.