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Gas boiler does not heat hot water heating works. We solve the main problem of gas boilers with hot water No hot water in the wall-mounted boiler

Constructive and modification solutions of modern gas boilers are aimed at uninterrupted and efficient work. Ariston boilers, popular in Russia, are no exception. But sometimes failures occur when the unit ceases to properly perform its main function - heating water to provide hot water and space heating. To understand what is the cause of the malfunction, why the Ariston boiler does not heat hot water need to understand how the system works.

Read in the article

Work principles

Gas boilers, as a rule, have two circuits - heating and water heating. Double-circuit devices are a combination of several blocks responsible for a certain functionality of the system. Thus, the gas block is responsible for the ignition and combustion of the burner, which allows the heat-conducting fluid to heat up, water is supplied in the water unit and the necessary pressure is provided in the line, the smoke exhaust unit throws into environment combustion products, the control unit controls the operation of all boiler systems.

When the unit is started using a pump, water is pumped into the system, passing through the pipes of the heat exchanger. As soon as the liquid has entered the water unit, the gas supply valve opens and the burner is ignited. The process of heating the body of the heat exchanger occurs evenly and is controlled by temperature sensors.

Important! Heating cycles are controlled by sensors. When the water temperature drops to certain temperature it is the sensors that transmit the impulse to the control module to resume heating.

When hot water enters the faucet, a flow sensor is connected. A signal is sent from it to the board, after which the three-way valve is activated and switches to heating the water supply.

The main problems why the boiler does not heat water

More often, malfunctions at the boiler are detected during the heating season, when both circuits of the device are working. There are two main problems faced by owners of wall-mounted gas boilers such as Ariston:

  • all boiler systems work, the device turns on, but heats the water weakly or does not heat at all;
  • the boiler does not start, and, as a result, there is no hot water supply.

Each of these problems has its own causes and solutions. To troubleshoot, you need to figure out what caused and caused them.

Before finding out the causes of a malfunction of the unit, you should look into the instruction manual, read the instructions and check the correct settings and connection of the device.

Note! Modern gas boilers equipped with a diagnostic system that detects malfunctions and displays an error code on the display. The instructions for the unit will help decipher the codes.

If all requirements and conditions are met, the most common causes of malfunctions should be considered:

  • blockage. Experts say that the use of unfiltered working fluid increases the risk of clogging of the heat exchanger tubes. The resulting scale reduces its thermal conductivity, which makes the unit work with an excessive consumption of energy. In this case, the optimum temperature regime is not achieved even with continuous operation of the device. Due to the heat exchanger settled inside the pipes limescale the metal undergoes corrosive changes, which can lead to its rupture.
  • Faulty pump. The circulation of the coolant can be stopped due to the accumulation of air, the so-called air plug in the pump. The second cause of a pump failure may be a rotor that is jammed. A circulation pump that has ceased to function can lead to overheating of the gas boiler.
  • The flow sensor is stuck. Inside the boiler is a sensor in the form of a turbine, resembling a small fan. When the turbine rotates inside the sensor, an electrical impulse is generated due to the fluid current, which is fed to the control unit. Thus, the electrical system understands that it is necessary to warm up the coolant.
  • Stuck three-way valve. Such a malfunction will not allow switching the water supply from heating to DHW. A valve stopper can occur due to blockage, both of the part itself and of the gas hose or filter.
  • Insufficient pressure. If the volume of liquid in the system does not create the desired pressure, the water supply valve does not open, which leads to burner ignition failure.

Possible nuances

Today on the market there are many gas wall-mounted boilers from various manufacturers. The principle of operation of the units for all models is essentially the same, but each brand has its own nuances that may be related to the causes of malfunctions and, as a result, poor water heating.

  • "Ariston" is an Italian brand that is distinguished by reliability. Brand boilers are adapted to domestic utilities and operating conditions. The most common cause of malfunctions is hard water, which contributes to the formation of blockages in the heat exchanger and circulation pump.
  • "Navien" - Korean autonomous gas boilers. They are easy to operate and efficient. A feature of the modification is the presence of two heat exchangers and the absence of a control panel on the body. The reason why the Navien boiler does not heat hot water well can be a stoppage of the equipment. This is due to the air pressure sensor, which, in the presence of reverse draft in the chimney unit, sends a signal to the control board, due to which the gas supply valve to the burner closes.
  • "Wailant". German quality is fully reflected in the units under this brand. Since the device is of European origin, its heat exchangers most often suffer, which become clogged due to inadequate quality of the conductive heat fluid.
  • Baksi is another representative of Italian manufacturers of autonomous heating equipment. He has simple and reliable boilers. The main reason why Baksi does not heat water, as experts in servicing such units note, is a factory defect, which is sometimes found in the model line of this company.
  • Arderia is a South Korean manufacturer. He provided a certain algorithm for controlling heating equipment. Incorrect settings may be the answer to the question of why the boiler stopped heating water.
  • Proterm is a subsidiary of the German company Vaillent. When operating these boilers, it is necessary to monitor the quality of the heat-conducting fluid, use cleaning filters to prevent clogging of the heat exchanger.
  • "Buderus" is another "German" in the domestic market of autonomous heating equipment, which has proven itself on the positive side. Like all Europeans, malfunctions can be caused by the formation of limescale inside the heat exchange system, as well as clogging of the working fluid flow sensor.

Possible Solutions

When the reason why the boiler does not heat water is known, you can try to eliminate it yourself. Manufacturers often make mechanical assemblies available for self-service.

Important! When troubleshooting on their own it is necessary to disconnect the unit from the power supply before starting work and free the internal components from the coolant

  • If the heat exchanger is clogged, you can clean it with special liquids, or by using proven home remedies for descaling. In the future, it is better to use filtering devices at the inlet of the coolant to the boiler.
  • If the cause is a faulty pump, you should disassemble it and inspect the rotor. If foreign particles are found that block free movement, it is necessary to remove them. The filter should also be inspected for clogging.
  • When the water flow sensor became the cause of the malfunction, it is necessary to remove the part from it, inside which the turbine is located. If, when rotated with a finger, it starts to click or slow down in the direction of travel, this means that there are foreign particles in the case. You should try to flush the turbine and clean each of its blades with a cotton swab dipped in cleaning fluid.
  • The three-way valve, if it caused a malfunction of the boiler, must also be cleaned, and at the same time the gas hose and filter must be checked.
  • Under reduced pressure, check all fittings and valves on the device, the pressure with which water flows from the mixer. If there are no leaks, and the pressure is weak or absent, then simply replenishing the water in the expansion tank will help solve the problem.

One of the main tips is to follow the operating rules and follow the recommendations of manufacturers. It is important to remember that prevention is always more profitable and better than repair. Timely maintenance, checking the main components of the system will extend the life of an autonomous heater.

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 fuel, use electric heating elements. 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. AT electronic circuits no moving parts at all. 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 into 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 electrical 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 problem of scale on long 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, boiler equipment can be equipped modern system remote control. Some manufacturers offer turnkey 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 check will help to identify problems on early stages. 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 technologies water treatment.

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 protective technology, which appeared recently, although it has been known for more than a hundred years. The fact is that previously only permanent magnets. They lose their beneficial features with 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 domestic 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 suitable 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.

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:


Faucet to vent their battery

It functions according to the principle 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;

  • clogged batteries what to do in this case? It is necessary to drain the water from the cooled batteries. If you see that water is flowing out with debris, and sometimes black liquid may pour out, you need to flush the system to clean water;
  • incorrectly made connection and piping. The pipe diameter may be incorrectly selected, shut-off valves are incorrectly installed, the heat exchanger is incorrectly connected. Check the manufacturer's recommendations in the instructions and correct the errors;
  • under reduced pressure, the unit also heats poorly, add water to the system;
  • the appearance of scale in the heat exchanger. It is necessary to flush the heat exchanger from plaque. Not in all models it is easy to remove the heat exchanger from the device. Where this is problematic, you can clean it without removing it. To do this, the boiler must be turned off, cool.

    Connect the pump hoses with the filtration system to the inlet and outlet and flush the heat exchanger with a special cleaning fluid. After that, be sure to flush the boiler clean water to remove chemical residues, otherwise the remaining particles of the product can lead to corrosion of the heat exchanger, pipes and radiators.

    Flushing the heat exchanger

    The use of reagents as additives to the coolant significantly reduces the formation of scale. But not all models are allowed to use antifreeze. Manufacturers Ariston (Ariston), Arderia (Arderia), Navien (Navien), Buderus, Viessmann (Vismann), Electrolux (Electrolux) prohibit the use of antifreeze, recommending the use of distilled water.

    In the instructions for the models Rinnai, Baxi (Baxi), Vaillant (Vaillant), Celtic (Celtic), Ferroli (Ferolli), AOGV 11 6, Beretta (Beretta), Bosch (Bosch), Neva Lux, Protherm (Proterm), Junkers, Koreastar (Koreastar), Daewoo is allowed to use antifreeze. It should be noted that not all antifreeze is suitable for these boilers.

  • filter clogging heating water also becomes the reason why the boiler heats the batteries poorly - clean the filter under a strong stream of water, after turning off and cooling the boiler. If the contamination is strong and cannot be cleaned, replace the filter;
  • heating medium temperature set too low, increase the temperature;
  • incorrect work circulation pump or its overheating also becomes the reason why your unit began to heat up the batteries badly, adjust its power;
  • 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 opening a faucet with hot water 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.

    How to eliminate the clocking of a gas boiler in hot water mode

    For heating and hot water supply of apartments and small private houses with one bathroom, double-circuit gas boilers are usually used. The owners of such boilers are often faced with the fact that either cold or hot water flows from the tap. As people say, the boiler is clocking, the DHW mode of the boiler periodically turns off and then turns on again.

    The principles of adjustment described in this article, setting up the hot water supply system suitable for double-circuit gas boilers of many brands and manufacturers, as well as gas water heaters.

    Why is the boiler either cold or hot water?

    A double-circuit gas boiler in hot water supply (DHW) mode operates in the power range from minimum to maximum. For example, in the instruction manual for the Protherm Gepard 23 MTV boiler, it is indicated that with factory settings the maximum power is 23.3 kW., the boiler provides water heating for temperature difference dT=30 about C, at the maximum consumption of hot water 11.1 l/min.

    Minimum boiler power in DHW mode 8.5 kW. It is not difficult to calculate that this minimum power is enough to heat water by the same temperature difference, for example dT=45-15=30 about C, with hot water consumption 4 l/min And for heating water flow 1.5 l/min, at which the boiler burner is turned on, it is necessary to operate the boiler with a power less than the minimum - only 3.15 kW.

    The design of modern mixers is done taking into account the need to save water. In addition, boilers and columns have hot water flow limiters. For example, in a house with a boiler connected to the central water supply, the following results of measuring the maximum hot water flow were obtained: through the horn of the bath faucet 6 l/min., in washbasin 4 l/min., in the kitchen sink 5 l/min. It is convenient to measure the water flow in the taps if you call line d.36 of the service menu of the Protherm Gepard (Panther) boiler, or measure the time it takes to fill a 3-liter jar with water (there is a stopwatch in the smartphone).

    Usually, in order to save money, users do not open the water taps for full flow. In addition, to obtain a comfortable temperature, hot water is always mixed with cold.

    The burner of the boiler in the DHW mode turns on at a water flow of 1.5 l/min Turns off at 1.1 l/min This hysteresis is a protection against periodical switching on/off of the burner due to fluctuations in the flow rate.

    Considering all these circumstances, the actual amount of water that the boiler should heat per minute will be approximately equal to - 1.5-4.5 l/min.

    It is obvious that the difference between the factory settings of the minimum and maximum boiler power, designed for heating 4-11.1 liters per minute, and the power required to heat the actual flow in the tap, will be significant. Boiler burner power within the minimum and maximum power settings (8.5 - 23.3 kW) is controlled automatically. It is obvious that there is a huge difference between the boiler power settings and the power required to heat the actual water flow (3.15 - 9.4 kW), leads to the fact that the boiler automation is not able to bring the boiler output in line with the needs of the DHW system.

    A large excess of the gas boiler power set at the factory in the DHW mode over the power required to heat hot water in the taps of the users leads to cycling (clocking) of hot water heating. The burner of the boiler in the DHW mode periodically turns on and off. Accordingly, from the tap comes either cold or hot water.

    Setting, adjusting the temperature of hot water in the DHW system


    heating diagram tap water double-circuit gas boiler depending on temperature ( T about C) and consumption ( Q l/min) hot water. The thick line shows the borders of the Working area. Gray zone, pos. 1 — boiler clocking zone (switching between ON/OFF).

    For normal water heating by the boiler, on the diagram the point of intersection of the temperature and hot water flow lines (working point) must always be inside the working zone, the boundaries of which are shown on the diagram with a thick line.

    If the hot water consumption mode is selected so that the operating point will be in the gray zone, pos. 1 in the diagram, the boiler will cycle. In this zone, with a small flow of water, the boiler power is excessive, the boiler is switched off from overheating, and then switched on again.

    It can be seen from the diagram that the boiler can normally heat water only when the hot water flow from the tap is in a limited range, 4-9 l/min. With a low flow rate, the boiler power is excessive and it cycles. And with a large one, the boiler power is not enough to heat the water to the required temperature.

    As mentioned above, there is no need to prepare large streams of hot water in the house. It is much more important to ensure comfortable use of hot water at a low consumption. To this end, the working area on the diagram must be moved to the left. It can be done if you reduce the power of the boiler burner by reducing the gas supply by adjusting the gas valve.

    How not to deal with clocking

    Some "experts" advise setting the hot water temperature lower, less than 45 o C, in order not to dilute the water in the mixer when parsing water, and open the taps to full passage. Thus, it is proposed to get rid of clocking, increasing the flow of heated water to the maximum. In many cases, this really helps, since the water flow and temperature fall into the working area on the diagram.

    In DHW systems with a double-circuit boiler or with a gas water heater I don't recommend doing that, and that's why. With this method, you have to spend water, and hence gas, much more than necessary. In addition, it is necessary to always keep a large flow of water from the tap, it is impossible to regulate the temperature of the water with a mixer - all this creates discomfort in using hot water.

    In addition, the display of a double-circuit boiler with a secondary DHW plate heat exchanger does not show the temperature of the hot water at the outlet of the boiler, but the temperature of the heating water at the outlet of the heating circuit of the DHW heat exchanger (return temperature from the DHW heat exchanger).

    In systems with a double-circuit boiler, in which water is heated in the secondary DHW heat exchanger, the automation controls and maintains a constant temperature of the heating water at the outlet of the primary circuit of the DHW heat exchanger (return temperature from the DHW heat exchanger), and the temperature of the hot water at the outlet of the secondary circuit of the DHW heat exchanger is not controlled.

    The temperature of the hot water at the outlet of the boiler will be as it turns out, depending on the degree of opening of the tap, on the temperature and pressure of the water in the water supply, on the thickness of the scale layer. That is, each time the tap is opened, the temperature of the hot water will be different.

    Therefore, the required hot water temperature at the outlet of the boiler cannot be pre-set on the display. If you set the heating water temperature on the display, for example 50 about C, then the temperature of hot water from the tap will always be less, and less each time in different ways.

    In a DHW system with a double-circuit boiler, it is more convenient to regulate the water temperature directly on the tap at the time of disassembly, mixing in the mixer with cold water. To make this possible, it is necessary to have some margin for the temperature of the water at the outlet of the boiler.

    For comfortable use of hot water from a double-circuit boiler or column, I recommend set the temperature on the display in DHW mode to 52 about S.

    Temperature value 52 about C chosen for the following reasons:

    • At a temperature of 54 about C and higher from tap water, an intensive release of hardness salts begins, which accumulate in the heat exchanger in the form of scale. Heating the water to a lower temperature protects the heat exchanger from scale deposits.
    • Temperature 52 about C remains high enough to allow adjustment comfortable temperature water in the mixer, mixing hot water with a small amount of cold. In rare cases, when more than heat(e.g. when filling a bath), it is more advantageous to increase the DHW temperature setting on the boiler display.

    The intensity of scale deposits in hot water depends on the temperature and speed of water movement near the heating source. According to studies, in still water, when the water in the tank is heated, the stone begins to form already at a temperature of 40 °С. With a high flow rate of hot water in the flow heat exchanger, the stone begins to form at temperatures above 54 °С.

    Setting the boiler burner output in DHW mode

    In order for the boiler in the DHW mode to heat the water evenly, not to cycle even with a minimum water flow, it is necessary to reduce the burner power, by reducing the gas supply by adjusting the gas valve. Thus, the entire work area on the diagram will move to the left. To do this, on the gas valve, reduce the factory settings for the minimum and maximum pressure at the gas outlet from the valve, in front of the burner.

    As a result of adjusting the gas valve, there will be no signs of cycling of the burner in the DHW mode when the hot water flow changes over the entire range, from the maximum (6 l/min) to the minimum specified in the instructions (1.5 l/min). The temperature of hot water can be regulated by a mixer, changing the flow rate of water and mixing it with cold water within limited, but quite comfortable limits.

    Adjustment, adjustment of the SIT gas valve

    SIT gas valve.

    SIT gas valve. 1 - measuring fitting of gas pressure at the outlet of the valve, in front of the burner; 2 - adjusting nut for maximum pressure (flow) of gas; 3 - adjusting screw for minimum pressure (flow) of gas; 4 — cover of the adjusting device; 5 - measuring fitting of gas pressure at the valve inlet, in the gas network.

    Manufacturers of double-circuit gas boilers of many brands install a gas valve from the Italian company SIT on the boilers. The settings for the maximum and minimum power of the boiler burner are made by turning the gas pressure adjusting screws located on the valve body.

    A U-shaped pressure gauge is connected to the measuring fitting (1) to control the gas pressure in front of the burner. The gas pressure value corresponding to the minimum and maximum boiler power is indicated in the factory instructions. For example, for a Protherm Gepard 23 MTV boiler with a minimum power of 8.5 kW corresponds to pressure 15 mm w.c.(millimeters of water column). For maximum power 23.3 kW gas pressure at the fitting should be 85 mm w.c.

    Adjustment of gas pressure in front of the burner in DHW mode

    about C.

    We remove the cover from the boiler and provide access to the gas valve and the ability to observe the height of the flame in the burner. We recommend connecting a U-shaped manometer to the measuring socket (1) of the gas valve.

    On the gas valve, remove the cover of the adjusting device (pos. 4 in the figure). The initial position of the adjusting devices - nuts and screws, relative to the body, mark with a colored marker, if it is necessary to restore their position.

    with maximum water flow(horn in bathroom 6 l/min).

    Adjust (reduce) the gas pressure in front of the burner using the nut for adjusting the maximum gas pressure (pos.2). When turning to the right, the gas supply increases, and when turning to the left, it decreases. The purpose of the adjustment is to find the limit when further rotation of the adjusting nut leads to a decrease in the height of the flame in the burner, to a decrease in the temperature of hot water from the tap and to a decrease in gas pressure at the measuring point (1). Leave the nut in a position close to the boundary found.

    As a result, the maximum power of the boiler will be less, and right border the working area on the diagram will shift to the left, to the point with coordinates, for our example, 60 about C and 6 l/min.

    Set the hot water temperature on the boiler display to 52 about C. (see above for setting the DHW temperature)

    On the gas valve, disconnect the modulator power cable. The boiler will go into minimum power mode.

    Turn on the DHW mode on the boiler by opening for the minimum flow hot water tap with sufficient water flow to turn on the boiler burner.

    Adjust (reduce) the gas pressure in front of the burner using the minimum gas pressure adjustment screw (pos.3). When turning to the right, the gas supply increases, and when turning to the left, it decreases. Visually observe the height of the flame in the boiler burner. The purpose of the adjustment is to reduce the gas supply to the burner (flame height) so that the burner works continuously and the temperature of the hot water from the tap remains constant, the boiler does not clock.

    As a result, the minimum boiler output will be reduced. The left border of the working area on the diagram will shift further to the left, to the point with coordinates, for our example, 52 about C and 2 l/min.

    Do not attempt to reduce the minimum pressure at the outlet of the gas valve too much. A very small gas pressure on the burner can lead to a violation of the stability of combustion, to the breakdown and extinction of the flame.

    Reconnect the modulator power cable and replace the modulator cover.

    We control the gas pressure in the network

    The gas pressure in the gas network may drop below that allowed for the operation of the boiler. It is necessary to periodically control the pressure, especially in cold weather, when the gas flow in the network is maximum.

    Static pressure and dynamic pressure are measured at the boiler inlet. Static pressure is when the boiler does not consume gas. The dynamic pressure is measured at the maximum gas flow rate of the boiler.

    The pressure in the gas network, at the inlet of the gas valve, is measured by attaching a tube of a U-shaped pressure gauge to the fitting pos.5. To measure the dynamic pressure, open the hot water tap to the full passage.

    The normal dynamic gas pressure at the gas valve inlet should be between 1.3 - 2.5 kPa (13 - 25 mbar or 132 - 255 mm. water. Art.). If during the measurement the value of the dynamic pressure goes beyond the specified limits, then it is necessary to contact the gas service.

    How to measure the gas inlet pressure and adjust the minimum and maximum gas pressure at the outlet of the SIT gas valve, see this video.

    A simple manometer for measurements on a gas valve can be made from a transparent plastic tube, filled with water and bent in the shape of a U. One end of the tube is put on the valve fitting, and the other is left open. The ruler measures the difference in water levels in the branches of the tube. The measured distance will be equal to the pressure in millimeters of the water column - mm w.c..

    On the gas valve fitting, you can tightly pull the tube with an internal diameter of 8 mm. For a tube of a different diameter, you will have to select an adapter.

    At the end of the measurement, do not forget to carefully tighten the locking screw on the measuring nipple and check its tightness.

    Adjustment, adjustment of the Honeywell gas valve

    Gas valve Honeywell gas boiler. The yellow wired connector is mounted on the stepper motor.

    Some modern boilers, such as Protherm Gepard and Protherm Panther, have Honeywell gas valves.

    The gas pressure setting at the outlet of the Honeywell gas valve is changed using a stepper motor. The stepper motor of the gas valve is controlled from the boiler control panel through the service menu.

    We will consider setting up a gas valve with a stepper motor through the service menu using the example of Protherm Gepard and Protherm Panther gas boilers.

    Access to the Protherm boiler service menu

    The electromechanical devices of the boiler (electrovalves, stepper and conventional electric motors, sensors) are controlled by the microprocessor of the electronic control board in accordance with the programmed program.

    The settings of the boiler operation program can be changed on the control panel using two menus - a public user and hidden service menu.

    Access to the service menu of the Gepard boiler

    The Protherm Gepard boiler is controlled from the control panel through the public user menu. How the owner manages the boiler is written in the instruction manual.

    On the control panel, you can call up another hidden menu - a service menu intended for specialists. The service menu becomes available on the display screen after entering the code.

    Press and hold the mode button (1) for about 7 seconds; the display will change - a number will appear 0 . - With buttons + or - (2), enter code, number 35 . - Confirm the code entry by pressing the mode button (1). After that, the display will show the 1st menu line in the form of symbols interspersed on the screen: d. 0.

    Buttons + or - d.**.

    Press the "mode" button to change from menu bar number designation " d.**” to the parameter value (the display alternates between the “=” symbol and the parameter value). - Change the values ​​of the displayed parameters using the + or - buttons (3) on the boiler panel. - 3 seconds after the change, the new values ​​are automatically confirmed. To reset the display, press the "mode" button for 3 seconds. After 15 minutes of inactivity, the display returns to normal on its own.

    Access to the service menu of the Panther boiler (Panther)

    The control panel of the Protherm Panther boiler has some differences from the Protherm Gepard boiler. The boiler control panel has a hidden service menu, which becomes available when entering the code.


    To access the service menu of the Protherm Panther boiler (Panther), you must: Press and hold the mode button (1) for about 7 seconds; the display will change. - By using buttons on the left + or - (2), enter the access code in the service menu - the number 35 in the left half of the display. - Confirm the code entry by pressing the mode button (1).

    After that, the display will show the 1st line of the menu in the form of symbols d.00 with the menu line number in the left half of the display, and the numeric value of the line parameter in the right half of the display. - By using buttons on the left + or - (2), enter the number with the required menu line number: d.**.

    To change the value of a parameter in the menu bar:- Change the values ​​of the displayed line parameters with buttons on the right + or - (3) on the boiler panel. - 3 seconds after the change, the new values ​​are automatically confirmed. To reset the display, press the "mode" button for 3 seconds. After 15 minutes of inactivity, the display returns to normal on its own.

    The service menu commands and the procedure for setting the power of the Protherm Panther boiler (Panther) are similar to those given for the Protherm Gepard boiler.

    Description of some service menu commands

    Line d.36- shows on the display the hot water consumption measured by the flow sensor, l/min. when dispensing hot water (read-only).

    Let's determine the consumption of hot water in our apartment (in the house). Line d.36 of the service menu shows on the display the hot water consumption measured by the flow sensor, l/min. We display the line parameter d.36 on the display, then open the DHW taps in the apartment (in the house) one by one for full flow and record the water consumption readings from the display.

    Line d.52- setting the minimum power of the boiler burner by shifting the minimum position of the stepper motor of the Honeywell gas valve. The range of possible parameter values ​​is from =0 to =99. The smaller the value of the parameter, the weaker the intensity of gas combustion.

    Line d.53- setting the maximum power of the boiler burner by shifting the maximum position of the gas valve stepper motor Honeywell. The range of possible parameter values ​​is from =0 to =-99 (negative values ​​with a minus sign). The smaller the value of the parameter, the weaker the intensity of gas combustion.

    Line d.88- Protection against water hammer in the distribution of cold water (for boilers KTV and KOV) . The ability to change the parameter leads to the elimination of the reaction to water hammer, which occurs in some cases in cold water pipelines. For example, at the moment of closing the automatic valve in the toilet flush tank (or washing, or dishwasher), a pressure surge (water hammer) may occur in the water pipes. The consequence of this may be a false operation of the tap water flow sensor (turbine), which will lead to a short-term unwanted activation of the boiler's DHW mode. Factory setting 0 = activation of the ignition process for heating tap water at a flow rate of 1.5 l/min. Changing the parameter to value 1 = activation of the ignition process for heating tap water at a flow rate of 3.7 l/min. In this case, the duration of the flow must be at least 2 seconds.

    Line d.96- Setting the boiler to the parameters set from the factory. In case the setting leads to incorrect operation or failures, it is possible to restore the factory settings of the boiler. Setting: 0 - replacement with factory settings will not be performed; 1 - will return to the factory settings Note: when you enter the setting of this parameter, the display always shows the parameter "0".

    Setting, adjusting the minimum power of the boiler with a Honeywell gas valve

    The boiler manufacturer Protherm Gepard (Panther) on some versions of the boilers, instead of the Honeywell gas valve, installs the SIT 845 Sigma gas valve. The setting of this valve is described above. There are no lines d.52 and d.53 in the service menu of Protherm boilers with SIT valve.

    Setting the maximum gas pressure:

    On the boiler display, set the maximum hot water heating temperature to 60 about C.

    We remove the cover from the boiler and provide access to the gas valve and the ability to observe the height of the flame in the burner. I recommend connecting a U-shaped pressure gauge to the measuring fitting at the valve outlet.

    Turn on the DHW mode on the boiler by opening the hot water tap to full flow with maximum water flow(horn in bathroom 6 l/min).

    d.53, press the “mode” button and see on the display the value of the gas valve stepper motor position parameter in the maximum power mode. For example, on a new boiler, the factory setting of the maximum power parameter in the line d.53 was = -17 .

    Decrease the value of the parameter in line d.53 step by step and fix the result. For example, set the line to =-30 (minus 30 is less than minus 17) and press "mode" for the changes to take effect. We look at the height of the flame in the burner and the value of the gas pressure. They haven't changed.

    The purpose of the adjustment is to find the limit when a further decrease in the parameter in line d.53 leads to a decrease in the height of the flame in the burner and to a decrease in gas pressure at the measuring point. In our example, the flame height and pressure began to decrease when the parameter in line d.53 was set to less than = -70 (remember, factory setting = -17)

    As a result, the right border of the working area on the diagram will shift to the left, to the point with coordinates, for our example, 60 about C and 6 l/min. The maximum power of the boiler will be reduced.

    Setting the minimum gas pressure in front of the burner:

    To adjust the gas valve, the boiler is switched to DHW mode. For this, we open for the minimum pass hot water tap with a flow rate sufficient to turn on the boiler burner.

    In the service menu, select the line d.52, press the “mode” button and see on the display the value of the gas valve stepper motor position parameter in the minimum power mode. For example, on a new boiler, the factory setting of the minimum power parameter in the line d.52 was = 72 and the burner cycled in DHW mode.

    We carry out experiments - reduce the value of the parameter in the line d.52 =60 , press "mode" to make the changes take effect, and check the result. If the clocking has not stopped, then we also reduce the parameter in the line d.52 = 50 and observe the change in the temperature of the hot water in the tap. So, step by step, we reduce the parameter in line d.52 until we achieve the absence of temperature fluctuations at a comfortable water flow.

    We reduce clocking to an acceptable comfortable level. Do not attempt to reduce the minimum pressure at the outlet of the gas valve too much. A very small gas pressure on the burner can lead to a violation of the stability of combustion, to the breakdown and extinction of the flame.

    For example, on a new boiler, the temperature of hot water in the tap reached 52 about C, after setting in line d.52 parameter =30 (remember, the factory setting was =72). There were no signs of burner cycling in the DHW mode when the flow rate changed over the entire range, from the maximum (6 l/min) to a minimum of 1.5 l/min. The temperature of hot water can be adjusted with a mixer, changing the flow rate of water and mixing it with cold water within limited, but quite comfortable limits.

    How will the settings of the gas valve for domestic hot water affect heating

    Reducing the pressure setting at the outlet of the DHW gas valve will also lead to a slight decrease in the boiler output in heating mode. But in most cases, the maximum output of a combi boiler is chosen to cover water heating requirements that exceed the required output for the heating system.

    For our example, the maximum boiler power will decrease from 23.3 kW. up to 12-14 kW. This power will be enough to heat a house with a heated area of ​​up to 140 m 2.

    The maximum power of a double-circuit boiler is usually more than is necessary for heating operation. Therefore, after setting the DHW mode, in most cases, it is enough to increase the maximum power setting when the boiler is operating in heating mode. How to do it

    If the boiler power in heating mode is still insufficient, you will have to restore the factory settings of the gas valve. In this case, to eliminate DHW clocking, I recommend connecting a boiler to the boiler.

    About the disadvantages of reducing the boiler power settings

    The service manual for the Protherm Gepard 23 MTV boiler indicates its efficiency in heating mode: 93.2% at maximum heat output (23.3 kW.) and 79.4% when operating at minimum power (8.5 kW.) Imagine how the efficiency will decrease even more if this boiler has to work with a minimum power of 4 kW. Please note that a double-circuit boiler during the year most of the time operates in heating and hot water mode with a minimum power. At least 1/4 of the consumed gas will literally fly uselessly into the pipe. But clocking, as already mentioned above, also reduces the efficiency of the boiler, leads to excessive consumption of water and gas, and makes the use of water uncomfortable.

    In the comments to the article, the reader Sergey writes:“The manufacturer did not just set the minimum and maximum power of the boiler. According to you, if it were all so simple, then the manufacturer, with the help of its service representatives, would reconfigure the boilers as you are talking about it. But the manufacturer in these cases insists to deal with the pressure and not with the boiler. As I understand it, this is due to the fact that changing the minimum / maximum range on the burner is dangerous, for the boiler in the first place. If the pressure of the gas supplied to the burner is lowered, the flame will go down, in which case the burner will be damaged over time?

    And this is my answer to Sergey:“My boiler has been working for the fifth year. Every summer I clean and inspect the burner. I don't see any signs of damage or overheating. I do the same for others. There is no protection against low gas pressure on the boilers. This means that the manufacturer believes that it is not dangerous.
    Low pressure is dangerous for boilers with burners, in which the gas is pre-mixed with air and already ready mix comes out of the burner. Then yes, at low pressure, the flame can even slip into the inside of the burner and really damage the burner.
    Most household boilers do not have a burner like this. There is a danger of extinguishing, blowing out the flame, but the boilers have protection that will turn off the boiler and give an error.
    The choice is up to the owner - either live with clocking, or change settings, or buy a boiler or another boiler.
    Manufacturers, sellers and specialists actually deceive buyers, with rare exceptions, they do not inform them about the cycle time of a double-circuit boiler at low water consumption. Buyers think that there will be normal hot water at the minimum flow rate specified in the instructions, and then it turns out that this is not the case. Reconfiguring greatly reduces the efficiency of the boiler. This information is not in the instructions and descriptions for users. If all this was explained to buyers, they would buy other boilers.”

    We choose the power of a gas boiler for the house correctly

    Most gas-fired double-circuit boilers that are commercially available are designed to operate with a minimum heat output. over 8 kW.

    Some manufacturers began to "cunning". In the boiler control program, limit maximum thermal power in heating mode. And indicate its value in the designation of the brand of the boiler. Boilers appeared on sale with an indication of the power in the brand of the boiler, for example - 12 kW. At the same time, in the boiler passport, the maximum power in the DHW mode remains 20 - 24 kW., and the minimum in all modes is more than 8 kW.

    On sale you can also find double-circuit gas boilers with a maximum heat output of 20 - 24 kW. and minimum less than 5 kW. Such boilers the best way meet the needs of heating and hot water systems of small private houses and apartments. At maximum power, the boiler operates in DHW mode. At minimum power - in heating mode.

    For the preparation of hot water and heating houses and apartments with a heated area up to 120 m 2, with one bathroom, I recommend installing double-circuit gas boilers with an extended operating power range:

      • with a maximum power of 20 - 24 kW.
      • and minimum less than 5 kW.

    Filter at the heating water inlet to the DHW heat exchanger

    Problems with hot water heating sometimes arise and are aggravated due to clogging of the filter installed at the heating water inlet to the DHW plate heat exchanger. The filter protects the DHW plate heat exchanger from dirt from the heating circuit.

    If the filter is heavily clogged with dirt, then in DHW mode this most often manifests itself as an error: “overheating of the primary circuit at the supply (NTC2)”. The overheating protection is activated and the boiler is turned off.

    For all brands of boilers, the filter is removed in different ways. But this procedure usually does not present any particular difficulties. No special tool is required. But it would be better to find instructions, a website, pictures or videos on the Internet on this topic. For the first time, you can invite a service specialist and see how he removes the filter.

    Cleaning the hot water filter of double-circuit gas boilers Protherm Gepard and Panther (Panther)

    1 - mounting rails, heat exchanger holders; 2 - holder screw; 3 - gasket; 4 - heating water filter at the inlet to the heat exchanger; 5 - DHW heat exchanger of a gas boiler;

    To clean the DHW heat exchanger filter:

    1. Close the taps on the supply and return of heating water.
    2. Open the drain valve on the boiler, on the right under the pump, and drain heating water from the boiler.
    3. Close the tap at the cold water inlet and disconnect the cold water tube from the boiler. Water will drain from the boiler through the open cold water pipe. Open the hot water taps to completely empty the DHW tract from the water.
    4. Remove screws (2) and holder (1) from both sides of the plate heat exchanger.
    5. Remove the DHW plate heat exchanger (5). Frame plate heat exchanger fastened with mounting rails to the base. After the tires are removed, pull the heat exchanger up and remove it.
    6. Remove spacers (3).
    7. Remove the filter (4) from the hydro group.
    8. Clean the filter and put everything back.

    It is recommended to change the gaskets between the heat exchanger and the base (3) every time during installation. DHW heat exchanger gasket, rubber ring: 22.2x13.5x5 mm. From the inside - an annular recess. Article number: 0020014166 (10 pieces).

    When reinstalling, check the correct location of the heat exchanger - the markings on its side wall should look forward. I encourage you to take a moment and descale the heat exchanger removed from the boiler. How to do this - read the following article on this topic.

    Reading time: 2 min

    Gas boilers are designed to create comfortable living conditions. Double-circuit units provide the living space with heat and hot water in the tap. But it happens that a working boiler heats water poorly and does not provide the necessary comfort.

    The degree of efficiency of the entire heating system depends on how the boiler works. If there are malfunctions in the gas boiler itself, then this can adversely affect the efficiency of the entire system and cause excessive consumption of energy resources.

    What happens when the boiler stops heating water? Let's analyze the causes and ways to solve this problem.

    How does a boiler work?

    For a clearer understanding of the situation, you need to understand the principle of operation of the boiler. Such double-circuit gas wall boilers, like "Baksi" or "Ariston" consist of several components. In the gas part, the incoming fuel is burned, the water part provides the supply of heated water from the heat exchangers to the heating system, the smoke removal part is responsible for the removal of combustion products outside the dwelling.

    After the boiler is started, the pump is turned on, providing the necessary water level in the system and the gas supply valve opens. The coolant moves in the heat exchanger, which is heated by the flame of the burner. The thermostat monitors temperature regime in the room, temperature sensors monitor the readings on the supply and return pipelines. Also, indicators of fuel pressure, coolant in the circuits, the presence of traction and combustion are taken.

    Depending on user settings temperature sensors set the water heating mode. The sensor on the return pipe turns off the boiler, depending on the achievement of the required temperature set for the return. However, the system pump does not stop running until the heat exchanger temperature drops.

    This is to prevent the water from boiling in it. As soon as the coolant cools down to the limit level, the electronics will send a signal to turn on the water pumping and the gas valve. The whole process will start over.
    When a tap is opened in the mixer in a double-circuit boiler, a flow sensor reacts, which informs the electronics about the need to switch three-way valve to DHW heating mode.

    Turning off the hot water tap switches back to heating mode. Some manufacturers provide for the heating of both heat exchangers during periodic switching.

    The boiler does not heat water for heating

    So, let's consider the main reasons why a gas boiler does not heat water for a heating system and what to do about it:

    • airlock. It is necessary to examine the heating system for the presence of air in the radiators. To eliminate this problem, you need to install an air vent. The principle of its operation is similar to the operation of an expansion tank, but it is able to maintain pressure in the system. Use an air vent to bleed air from the system. It is important to inspect the valve itself for mechanical blockage - scale may be present there;
    • corrosion in radiators. You can determine the blockage of heating devices by draining water from the system. If the water flowed dirty, then it is necessary until visually clean water appears;
    • connection errors. Hot water may not flow if the diameter of the pipes is not the same as provided for by the project or instructions. It is necessary to check the compliance of the pipeline, the correct connection and the quality of the installation of valves;
    • insufficient network pressure. You should try to add water to the heating system, as there may not be enough pressure to trigger the automatic ignition of the burner;
    • the presence of scale in the heat exchanger. The first sign is the prolonged heating of the coolant and the heating of the batteries. It is necessary to get rid of deposits and carry out boiler water treatment. To do this, you need to disassemble the boiler, and dismantle the heat exchanger assembly.

    Before this, you need to shut off the flow of gas and water to the device. Then, flexible connectors from the pump are connected to the heat exchanger and it is washed with a composition with a special cleaning agent, which can be purchased commercially. After that, the parts are washed with water.

    It is important to understand that adding chemical reagents into the coolant prevents and reduces the appearance of deposits on parts. But before using the reagents, you need to read the instructions for the boiler, since some manufacturers, such as Ariston, Electrolux, Buderus, Navien or Arderia, do not provide for the use of chemical additives in the coolant. In this case, you can use water purification filters or distilled water.

    Some manufacturers allow the use of antifreeze instead of water in the heating system. This substance can be used in the following boilers: Baxi, Vaillant, Proterm, Beretta, Korea Star. However, it should be understood that each manufacturer recommends using their own antifreeze;

    • filter clogging. If the filter screens are clogged with mechanical debris, the radiators can also warm up poorly. Therefore, the filter should be regularly checked and cleaned by rinsing with water. If clogging occurs too often, then such a part must be replaced;
    • wrong setting. First of all, with little or no heating, it is necessary to check the settings of the control unit. Insufficient temperature may be set and the gas does not heat the water;
    • malfunctions pumping equipment. If the pump power is not enough to ensure good circulation, then it may turn off when it overheats. This can happen when the DHW circuit is turned on;
    • improperly selected heating devices. If radiators with inappropriate heat transfer parameters and design are installed in the system, this can also lead to weak heating;
    • incorrect slope of pipelines. Most often this problem occurs in systems with natural circulation. Regulatory documentation specifies that the slope of the pipes should be from 10 mm per meter of pipe. In case of non-compliance with these requirements, circulation may be disturbed and, as a result, there will be no heating due to the low coolant flow.

    The boiler does not heat hot water

    In addition to the lack of heating of the heating system, it happens that the gas boiler does not heat the hot water circuit.

    The most common cause of this negative phenomenon is the critical formation of scale in the heat exchanger.

    After all, the scale has a structure that limits the passage of the coolant, as well as taking away its heat. This is due to the thermal conductivity of salt deposits - it is much lower than the thermal conductivity of the metal from which the heat exchanger is made. Therefore, the boiler does not heat hot water well.


    It is also possible that a piece has moved away from the salt deposit, blocking the flow completely, which leads to a complete cessation of the supply of hot water.

    The next reason that the boiler does not heat water is the malfunction of the flow sensor.

    Structurally, the sensor is a bladed device through which water flows, which is a condition for its operation, because it sends a signal about the presence of a flow to the electronics, which, in turn, starts heating the water again. It happens that the sensor is clogged, but it can be cleared of blockage without removing it.

    The device has the shape of a cylinder and is located near the circulation pump. To start cleaning, open and close the tap near the sensor. In case this does not help, then it should be unfastened and removed, manually cleaned and replaced. If this does not help, then the sensor is most likely defective and needs to be replaced.

    The reason for the lack of water in the DHW circuit may be a faulty three-way valve.

    It is designed to shut off the heating system when the hot water tap on the mixer is opened. If the valve does not work, the boiler does not switch to DHW heating from heating water to heating. The first cause of its failure may be a blockage of corrosion products, which must be disposed of.

    If this does not help, then the valve should be replaced. It is also possible that the hose system and filter are contaminated. This problem is barely noticeable on the heating circuit, and on the hot water circuit it will be more noticeable. These items need to be cleaned.