A double-circuit gas boiler does not heat water well. The boiler does not heat or heats hot water poorly: cause and solution. Use a recirculation pump

When problems arise with the preparation of hot water in a double-circuit boiler, it is necessary first of all to determine according to which scheme the boiler operates in the DHW mode. There are two options: bithermic heat exchanger and secondary heat exchanger.

In the first case, the heating circuit and the hot water circuit are combined in one heat exchanger - the primary one. When water preparation is required, the heating circulation pump stops and the entire boiler output is given to the passing tap water.

In another case, the boiler is equipped with an additional (second) plate heat exchanger and a switch (three-way valve). When it becomes necessary to prepare water, the heat carrier from the heating circuit is directed to the second heat exchanger, through which heat is transferred to the flowing tap water. At the same time, the pump continues to work - to drive to pump the coolant in a small circle.

Therefore, for different schemes, problems with hot water should be diagnosed differently.

The most common problems:

Baksi boiler does not heat hot water well

baxi boiler does not heat water (hot water does not turn on)

If the boiler does not turn on as needed

You open the mixer valve, but the boiler does not react and does not try to ignite the burner, and no errors occur. Regardless of the scheme of operation of the DHW circuit of the boiler, a sensor is installed on the outlet pipeline, which determines that the water has begun to be parsed. It is also called a DHW flow sensor. There are different types of sensors: some simply detect the presence of water movement in the pipeline, others can quantitatively measure the flow. The latter are used to provide greater comfort due to precise control of the burner power depending on the flow rate.

In both cases, at the beginning of the water flow from this sensor, a signal must be sent to the control board. If for some reason this does not happen, the boiler will be idle.

The sensor type is easiest to determine by the number of contacts. Two means it is a closing microswitch. Three - a sensor with a flow meter.

Sensor Diagnostics

If the flow sensor is a microswitch, then for diagnostics it is enough to check the contact closure with a tester. To do this, disconnect the contacts from the sensor, connect the tester in the “ringing” mode, turn on the water tap. If the circuit does not occur, then the sensor is faulty and requires inspection and, if necessary, replacement. It happens that the accumulated dirt interferes with the circuit and it is enough to clean it. Poor quality of tap water and lack of pre-filters is the most common problem. Reed sensors contain a magnet, so they attract rust microparticles and quickly fail.

Sensors with a flow meter register the amount of water flow, which can usually be displayed on the boiler display. For BAXI boilers you need:

hold the “i” button to access the information menu for 5 seconds

use the DHW temperature adjustment buttons to scroll to parameter A08 (actual water flow through the sensor, liters per minute * 10)

Now it remains to compare the actual water flow from the tap with the sensor flow. If the actual flow does not match the value of the sensor, then most likely it needs to be replaced.

Since the mechanical part of the flow sensor is a turbine, in case of contamination, it can wedge and the signal from the sensor disappears. No signal from the flow sensor - the boiler stops heating water.

The three-way valve is installed in boilers with two heat exchangers. When a signal is received from the flow sensor, the electronics give a signal to the valve and the heated water from the first heat exchanger is sent to the second heat exchanger, where heat is transferred to the passing tap water. If, for example, actual switching does not take place (valve defective), then the heating medium will continue to circulate in the heating circuit and there will be no heat transfer to the hot water circuit.

If, for example, a valve closes the heating circuit only partially due to a malfunction, then there will be problems with insufficient heating of hot water, since part of the heat will go to the heating system.

Burner modulation errors

To heat running water, in most cases, a boiler power close to maximum is required. In modern boilers, the burner power is regulated over a wide range. Adjustment occurs by changing the amount of gas supply by the gas valve. The amount of adjustment is determined by the control board, depending on the logic of operation and settings. The process can be observed visually by the height of the flames on the burner.

If the boiler settings are set to 100% boiler power in DHW mode, but visually the flames on the burner are weak, or obvious interruptions are visible, then you should check:

gas valve setting (static and dynamic gas pressure)

control board

Such checks may only be carried out by a qualified technician.

Temperature sensor malfunction

The boiler determines the actual temperature of hot water according to the readings of the temperature sensor. Therefore, if for some reason incorrect readings are received from it, the boiler may not work correctly in the hot water preparation mode. The temperature sensor is a thermistor with resistance versus temperature. Checking such a sensor is to measure its resistance at a known temperature. Baxi boilers are equipped with NTC sensors with an inverse dependence of resistance on temperature. At room temperature, the sensor resistance should be approximately 10 kOhm, at a temperature of 45 degrees 4.3 kOhm.

Clogged heat exchanger (reduced capacity)

Often scale or dirt build-up on the inside walls of the heat exchanger is the cause of problems with hot water. If tap water does not undergo preliminary filtration (coarse cleaning) and the temperature of hot water is too high, the heat exchanger walls become overgrown with scale and dirt over time, their thermal conductivity and flow area decrease. Each time the user increases the DHW temperature on the boiler more and more to get the desired result on the mixer. With an increase in temperature, scale forms even faster and, as a result, the DHW temperature of the boiler is at its maximum, and the water is not heated enough. This process has a particularly negative effect on a boiler with a bithermic heat exchanger. Plate heat exchangers lend themselves well to flushing.

Control board errors

The control board should be considered as the cause of hot water problems when all other checks have failed. The cause may be a malfunction in the flame modulation circuit. The boiler control unit constantly adjusts the burner power depending on the conditions, and if there is a malfunction on the board, the boiler may spontaneously reboot or turn off when reaching the maximum power, which in most cases is required in the hot water preparation mode.

As board errors, it is still possible to incorrectly configure it. But this only applies to those cases when problems appeared after its replacement. BAXI boards are universal and require customization for a specific boiler.

Installing a gas boiler allows you to forget about cold water in batteries and taps. Double-circuit models are able to simultaneously work for heating and hot water supply (DHW) of the room. But what if the boiler does not heat water? If you are faced with a similar problem, our recommendations will help you find the cause and fix the problem yourself.

The principle of operation of the boiler

To understand the causes of the breakdown, you need to understand how the boiler works. Double-circuit devices "Ariston", "Baksi" and other models have several blocks. Ignition and combustion take place in the gas node, the water node is responsible for the water supply and pressure in the line. The chimney block brings combustion products to the street.

As soon as you start the boiler, a pump is activated that pumps water into the system. The gas valve opens. The liquid circulates through the tubes of the heat exchanger, and the burner evenly warms up its body. Sensors control the heating process. As soon as the temperature reaches the set temperature, the gas supply is turned off, heating stops.

When the temperature begins to decrease, the sensors will send a signal to the control module - the heating cycle will start again.

When the mixer is opened, the flow sensor is triggered. It gives a signal to the board to switch the three-way valve to DHW heating. When the mixer closes, the valve switches to the heating system. Some models are equipped with a "quick start" mode. Then the valve periodically switches, heats up both the first and the second heat exchanger.

Why does the boiler heat poorly, does not gain temperature

No hot water? Why is the technology not working? Sometimes it's about external factors. Let's consider in more detail.

The appliance works, but does not heat up or heats up weakly

Airlock. Check if air has accumulated in the batteries. Use faucets to remove excess air. If you do not have an air vent on the radiators, then you need to install one. Adjusting its faucet, you can release the accumulated air in the system.

Also inspect the valve for blockage. Most of the time it gets clogged up.

Clogged radiators. After cooling, drain the water from the pipes. If it is very dirty, run it through the batteries until a clean one flows.

Wrong connection. If there is no hot flow, make sure that the diameter of the pipes corresponds to those stated in the instructions. Are the hoses connected correctly, shut-off valves installed?

Low line pressure. It is not enough to open the valve and ignite the burner. Add water.

Accumulation of scale in the heat exchanger. You may notice that the equipment heats up the liquid for a long time, the batteries heat up slightly. Clean the radiator tubes from deposits. To do this, it is better to remove the knot, but this can not be done in all models. Therefore, remove the casing, disconnect the device from gas and water. Connect the pipes from the pump to the heat exchanger, run the cleaning liquid through the system. Special tools can be picked up in the store. Then rinse the parts with running water.

The addition of reagents to the heat transfer fluid helps to reduce the formation of salts on the parts.

When buying, it is important to pay attention to the brand and model of the boiler. For example, manufacturers of "", "", "", "", "" prohibit the use of a reagent. It is recommended to install cleaning filters or use distilled water.

Antifreeze can be applied to models, "", "", "", "", "". But for each manufacturer, a separate reagent is produced.

Filter clogged. Another reason for poor battery warm-up. The mesh filter is clogged with small debris, so it is periodically removed and cleaned under running water. In case of severe blockage or wear, it is better to replace the part.

Incorrect adjustment. Check the set values ​​on the panel. Perhaps the temperature is too low, so the gas does not heat hot water.

Problems with the operation of the circulation pump. Overheating, the pump turns off when hot water is turned on. Its power may not be enough for normal circulation. Adjust settings.

Battery design does not match your equipment. Each design has its own permeability and heat transfer. The wrong choice leads to a decrease in heating due to the permeability of the system.

Non-compliance with the slope of the highway. The problem is typical for systems with natural circulation, which is ensured by compliance with installation standards. According to the documents, the slope of the pipes for each linear meter must be at least 10 mm. No slope - no heating. The coolant stagnates, the batteries remain cold.

The gas boiler does not turn on, does not provide hot water for domestic hot water

The main cause of malfunctions is salt deposits. The larger the scale layer in the heat exchanger, the worse the conductivity. The water heats up for a long time, a thin, slightly warm stream flows at the exit. Also, a piece of scale could break off and block the passage to the mixer. What to do in this situation, we described above.

Flow sensor problems. The part works on the principle of a fan, which rotates due to the movement of the flow. The sensor may not work if it is clogged. For cleaning without dismantling, open and close the tap located near the circulation pump.

If the procedure did not help restore operation, you will have to remove the sensor, clean it and reinstall it.

Three-way valve malfunction. If the valve is stuck or broken, it will not be possible to switch the water supply from the heating system to DHW. The cause of the problem could be a clogged part, gas hose or filter. Clean all elements.

There are many reasons for failures. To determine what problem has arisen in your circuit, the signs we have described will help. Pay attention to the operation of the technique and compare with the indicated problems. If you cannot fix the problem yourself, contact a specialist.

If gas boiler does not heat water for hygienic or general technical needs, the problem can be solved by heating the required amount of liquid in a saucepan. Much more problems will arise in winter when the heating system is blocked. With a long absence of hosts, freezing of the system is possible. The subsequent restoration of its performance is associated with significant financial and time costs. To eliminate such negative situations, it is necessary to select and apply a set of effective preventive measures.

Design features of the gas boiler Baksi (baxi), Navien, Ariston

In any case, familiarization with the technique of this class and the features of modern models is useful. This knowledge will help to choose the right equipment, not to make mistakes during operation.

In household boilers Baxi (baxi), Navien and Ariston, gas, diesel and solid fuels are burned to heat water, electric heating elements are used. For a more complete use of the potential of energy resources, heat exchangers are being improved. They make long ducts of complex shape to ensure that the liquid remains in the working area for a long time.

Compactness is the current trend. Manufacturers offer gas boilers with square bodies of relatively small thickness. Some models, due to their aesthetic characteristics, deserve to be placed in a conspicuous place.

The next feature is the introduction of automated control systems. They control the combustion process, change operating modes, taking into account the readings of temperature sensors on the street and in separate rooms. When overheating, the equipment turns off without user intervention.

It is necessary to carefully consider situations when the Baksi gas boiler does not heat water. This happens, for example, when the supply of energy resources is interrupted. It is not difficult to make an appropriate check even without special professional training.

Circulation pumps, valves, other typical components and assemblies rarely fail. Their designs are designed for many years of operation without mandatory maintenance. There are no moving parts in electronic circuits. Their breakdowns are due to marriage. Subject to the rules established by the manufacturer, the resource of modern gas heating boilers is more than 10 years.

Voltage surges in the power supply network can damage the electrical part of the equipment. To exclude such influences, an external stabilizer is installed. Checking the grounding system will come in handy. This completes the set of preventive measures for this group of problems.

It is much more difficult to provide protection against the most common cause of breakdowns in gas boilers - scale. It is she who will be studied in detail in this article. When heated, calcium and magnesium salts are converted to a solid state. It is these impurities that clog narrow technological holes in heat exchangers. They also form a porous structure on the surface of electric heating elements. With a significant violation of the normal heat dissipation, their cases are damaged.

To prevent the formation of scale and lime inside the boiler, it is advisable to install non-chemical filters (water converters), magnetic and electromagnetic, which will ensure a long "life" for your boiler and an uninterrupted supply of hot water, as well as protect the heating circuit.

Such filters (scale converters) as AquaShield or MWS do not use chemical reagents and replaceable cartridges in their work. Once you install such a device in front of the boiler, you will forget about the scale problem for many years!

Troubleshooting: why does a gas boiler not heat hot water well?

If the gas boiler does not heat hot water well due to clogging or rupture of the tube in the heat exchanger, repairs are necessary. It is performed by replacing a failed node. Threaded connections are not used in this case, so it will be difficult to independently disassemble and subsequent installation. To create a high-quality soldering connection, it is better to invite an experienced craftsman. A qualified specialist will provide the necessary level of quality, provide written guarantees.

Knowing about the problem in advance is not easy. The scale layer grows slowly, so it will not be possible to register a clear decrease in power. Extraneous noise can be caused by the passage of sand and other mechanical impurities through the pipes. Technological openings are too small for visual inspection. For its implementation, dismantling is required.

This information explains why these types of emergencies occur unexpectedly. To prevent their development into a more complex problem, it is possible to equip boiler equipment with a modern remote control system. Some manufacturers offer ready-made solutions in the form of an additional electronic unit and specialized software.

The corresponding application is downloaded to the smartphone. The advantage is the ability to remotely change settings, check the readings of temperature sensors. If the Navien gas boiler does not heat hot water due to scale, replacing the heat exchanger is not enough. These same contaminants reduce the inner diameter of the pipes, narrow the ducts in the radiators. A complete system cleanup is required.

This procedure is performed according to the following method:

• Drain water into drain.
• Rinse all circuits sequentially, or simultaneously with a special solution.
• It is also used to clean the heat exchanger, if it is only clogged and can be further operated.
• After assembly, the performance of the system is checked under pressure.
• Eliminate identified defects (cracks, loose connections).

Aggressive chemical compounds are used to remove calcium solutions. The duration of a standard procedure for one household object is several hours. Appropriate corrections are made taking into account the real state of the system. Strong acids can damage metal parts, solder joints of the Ariston double-circuit boiler. For this reason, experienced teams take repair tools to fulfill orders.

Independent implementation of such procedures is possible. But for many ordinary users, it is not advisable for several reasons:

• You have to purchase expensive equipment for pumping liquids that will be used.
• Independent selection of the optimal composition of the solution will cause difficulties.
• During this procedure, there are no mechanisms for operational control of processes within the pipeline system. This increases the likelihood of breakdowns.
• In case of personal performance of operations, an official warranty obligation of a third-party contractor will not be received. All future problems will have to be solved at your own expense.

In addition, it should be noted that careless handling of aggressive chemical compounds can cause harm to health.

Preventive actions

Specialists of enterprises offering flushing recommend doing it every heating season. It is combined with a general inspection of the equipment. The frequency is adjusted taking into account the level of rigidity, the intensity of operation of gas double-circuit boilers Baxi (baxi), and other significant factors.

These tips are really helpful. Regular cleaning will prevent more complex procedures. Simultaneous checking will help to identify problems at an early stage. However, it is necessary to emphasize the main drawback of this technology - it can damage the equipment itself. It is especially unpleasant if defects appear during the heating season. It will be quite difficult to prove the guilt of the workers who did the cleaning.

Instead of using potentially dangerous techniques, effective protective measures are used. They are based on modern water treatment technologies.

So that scale does not form in the Navien or Ariston heating boiler, they are installed in front of it. They dissolve during the passage of a stream of water, create dense shells around microscopic scale particles (at the first stages of growth). After such a "modification" harmful impurities are not able to join the walls and each other. They pass freely along the contour, are removed into the sewer.

The second method is the replacement of harmful compounds with sodium ions. This procedure is carried out using special resins. They fall asleep in two large containers that work alternately. As contaminants accumulate, flushing is performed using an inexpensive saline regeneration solution. Such equipment is used for general protection of apartments, cottages, and other real estate objects.

The next reason why a gas boiler does not heat hot water and its solution is a protective technology that has appeared recently, although it has been known for over a hundred years. The fact is that previously only permanent magnets were used for descaling. They lose their useful properties over time. Moreover, the effect of "addiction" was experimentally found, when calcium and sodium compounds cease to respond to the corresponding influences.

Today, the technique has been improved! Today, electromagnetic converters with high-frequency oscillation generators are used. With minimal energy consumption (5-20 W per hour), they operate at a distance of up to 2 km along the length of the pipeline from the installation site of the Baksi or Proterm heating boiler. This technique retains its initial efficiency throughout its entire service life.

Ultrasound can grind scale particles, eliminate old formations. But this technology is rarely used. Like acids, it can destroy the structural components of the water supply system. It should also be noted the probability of occurrence of harmonic oscillations in the sound range.

Membrane technologies provide a high level of purification from various impurities, including hardness salts. But standard household installations process no more than 200 liters. liquids per day. This is not enough for the needs of the Vailant heating boiler and hot water supply.

Features of different boiler cleaning technologies and conclusions

If the gas boiler has stopped heating water, you have to repair it. To extend the life of the Buderus or Ferroli heating boiler and prevent accidents, different methods are used. To choose the right option, you need to pay attention to the following details:

• Rinsing with aggressive chemical compounds does not eliminate the problem, but eliminates the scale that has already formed.
• Polyphosphates pollute water, so this protection is used only for the heating circuit.
• Sodium compounds are harmless (this is ordinary, well-purified edible salt). However, after appropriate treatment, the water will acquire a pronounced taste.
• Ion-exchange fillers are sensitive to temperature, humidity, various impurities. It is necessary to clarify the requirements that are set out in the official instructions of the manufacturer of the Navien double-circuit boiler.
• To connect electromagnetic transducers, you need a current source of appropriate power. To ensure its continuous operation in difficult conditions, autonomous emergency power circuits are used.

When determining the reason why the Navien gas boiler does not heat or does not heat hot water well, these are 3 protection methods that must be taken into account: water hardness, architectural characteristics of the property.

Cats on cold batteries do not sleep.

Boiler malfunctions

Typical problems with the operation of heating equipment:

• malfunction of the built-in pump;
• the heat exchanger is clogged;
• three-way valve does not work.

If the boiler is working, the radiators are cold, experts recommend, first of all, to assess the technical condition of the main heating element. More specifically, to establish whether the built-in device works . This detail is an invariable attribute of modern equipment and is designed to increase the efficiency of its work. Very often, after a long period of inactivity in the summer, the pump may become clogged or covered with a layer of limescale. As a result, it is untimely to remove the heated coolant from the heat exchanger. The boiler is boiling, and the batteries are cold.

It is strictly forbidden to independently repair such complex equipment as a boiler. In this case, either a specialist from the service center is called to the house, or a repairman who has the appropriate certificate or permission.

Experts do not recommend using ordinary tap water as a coolant, as it is hard. Dissolved salts, when the temperature of the coolant rises, settle on the heat exchanger. As a result, the following problem arises: the boiler is working, and the batteries are slightly warm. Scale reduces the thermal conductivity of the heat exchanger, so the water in the circuit does not heat up, although the heating element constantly works with an excessive consumption of energy. You can fix the problem by changing the coolant and cleaning the heat exchanger. How to clean the heat exchanger correctly, the video will help you figure it out:

A double-circuit boiler heats water, but does not heat batteries. Here you need to pay attention to the serviceability of the three-way electric valve. It is responsible for switching the bypass from heating circuit service mode to DHW and CO mode.

Problems with the heating circuit

The pump must be selected according to the requirements of the heating circuit.

Failures in the operating mode of the heating circuit are not always associated with a malfunction of the main heating element. If the boiler works, but does not heat the batteries, the reason must be sought in the wiring itself.

The list of the main malfunctions of the heating circuit:

• the filter on the return line or the needle valve (Mayevsky's crane) is clogged;
• insufficient power of the circulation pump;
• the rules for installing a heating circuit with natural circulation are not observed.

Any of the above problems should be addressed before the start of the heating season. Otherwise, the room may be left without heat for several days, since the repair involves the complete draining of the coolant.

So, why does the boiler not heat the batteries if everything worked fine over the previous years? The reason is a mud plug, which has formed on the filter of the heating circuit and by itself completely blocks the flow of the coolant. It is solved simply - the water is drained from the pipes or with the help of bypasses its circulation is blocked, the filter is cleaned. To prevent the recurrence of such a situation, it is necessary to make a complete replacement of the coolant with parallel .

In a gravity system, the slope of the pipes is of key importance.

The second reason why the boiler is working and the batteries are cold is the insufficient power of the circulation pump. The performance of the device is not enough to timely and efficiently pump the entire volume of coolant. Or in the house, the heating system has branches that are at a significant distance from the pump. As a result, the circulation pump overheats, the heating equipment works with excessive energy consumption, and the radiators remain cold. The solution is to change the coolant pumping device to a more powerful one.

If the house has a two-pipe heating circuit with natural water circulation, and during the heating season it is often noticed that the boiler is on and the batteries are cold, then the reason lies in the non-compliance with the slope of the main. According to regulatory documentation, only a pipe slope of 10 mm per linear meter in a heating system with natural circulation will ensure the normal movement of the coolant. As a result - uniform heating of the batteries throughout the house. If there is no slope, the coolant stagnates, which negatively affects the temperature of the radiators. You can solve the problem by completely redoing the wiring.

Why are the batteries cold when the boiler is running?

The low efficiency of the heating system can be the result of malfunctions of both the circuit itself and the main heating element. In the case of a heating device, it is necessary to pay attention to the three-way valve, the functionality of the pump and the technical condition of the heat exchanger. Typical problems for heating distribution are clogging of the filter, insufficient power of the circulation pump and lack of slope of the pipes of the circuit with natural water circulation.

2017-06-07 Evgeny Fomenko

Why the boiler does not heat water for the heating system

There can be many reasons why a gas boiler does not heat water for heating. The main ones and ways to eliminate these causes will be discussed below.

The boiler turns on, but the heating does not heat.

Possible causes and their elimination:

It functions on the principle of an expansion tank, without reducing the pressure in the system. After a long downtime of the unit, check the valve, it may become clogged with scale;

wrong battery design. Batteries must correspond to a specific heating mode, since each type of radiator has an individual heat transfer value depending on this mode.

The principle of operation of a double-circuit heating boiler

Using the example of a gas unit, consider the principle of operation of a double-circuit boiler. The design of the unit is a system of blocks, the operation of which is interconnected and controlled by a security system, which includes various sensors. The main blocks are the gas block, where ignition and combustion take place, the hydraulic block, which regulates the supply and pressure of the liquid, the smoke exhaust block, which removes the products of gas combustion.

When the boiler is turned on, the circulation pump is initially started, then gas is supplied using the gas valve. Automatic ignition ignites the gas, in the process of gas combustion the heat exchanger heats up, heating the coolant passing through it. In this mode, the unit will work for some time until the parameters that are controlled by the sensors change.

The sensors monitor the temperature in the room, in the return flow, gas pressure, system pressure, draft flow, flame presence. Temperature sensors can control the temperature at the inlet or outlet of the heating circuit. If there is a sensor on the return, when the set temperature is reached, the thermostat sends a signal to the electronic board, which, having processed it, turns off the gas supply.

In this case, the circulation pump will work for some more time in order to cool the heat exchanger. This is done so that the remaining heat in the heat exchanger does not bring the coolant to a boil. After cooling to the set temperature of the water in the system, the electronic board will start the pump, the gas valve will open the gas and the entire cycle of operation of the double-circuit boiler will be repeated.

When a hot water tap is opened, the flow sensor is triggered and the control board switches the three-way valve to heat the secondary heat exchanger. The heating of hot water in the system is a priority, i.e. immediately after you open a hot water tap, the entire system will only work to heat this water.

When the tap closes, the reverse process occurs - the board transmits a signal to the three-way valve, it closes the DHW system and the unit again starts working on the heating circuit. It should be remembered that the unit will take some time for hot water to flow from your tap.

Some appliances are equipped with a "quick start" or "comfort" function. This function allows the boiler to switch the three-way valve from time to time and heat the water in the secondary heating medium.

DHW does not heat up - causes and troubleshooting.

The most common reason why the DHW is not heated is the strong formation of scale inside the heat exchanger. Scale not only narrows the flow of water in the heat exchanger, it significantly reduces the temperature of the water.

The reason for this is the thermal conductivity of scale salts is many times less than the thermal conductivity of the metal from which the heat exchanger is made. The unit does not give (does not supply) hot water or it runs weakly if a piece of plaque has broken off and blocked the fluid flow.

Hot water does not flow to the faucet when the flow sensor does not work. It is a fan that works when water flows through it. while the signal from it goes to the control board, it gives a command to heat the water. the sensor can become clogged, it can be cleaned without dismantling.

The sensor is a cylinder located near the circulation pump. To clean, simply open and close the tap in front of the appliance. If this procedure does not work, you will have to dismantle it, clean it and put it in its original place. If the sensor is not working, you will have to change it.

If the three-way valve is faulty, the unit will not produce hot water. The purpose of the three-way valve is to shut off the heating system when a hot water tap is opened. When the valve does not switch, the boiler continues to heat water for heating.

The cause of a valve malfunction may be an elementary blockage, for example, a piece of rust. If the problem is more serious, replace the valve with a new one. In addition, one of the simple reasons why hot water does not run from the tap may be clogging of the gas hoses or gas filter.

Three-way valve in section

On heating, this will not be so imperceptible, but on the temperature of the water from the tap it will be felt more significantly. Clean hose and filters. Some of the points listed above can also cause problems with heating and hot water in wood, electric and solid fuel (TT) boilers, provided that the design details are similar.