The gas boiler does not heat the water - causes and remedies. Why the gas boiler does not heat the water The double-circuit boiler does not heat hot water the reason

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

Boiler working principle

To understand the reasons for 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 unit, the water unit is responsible for the water supply and the pressure in the line. The chimney unit removes combustion products outside.

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

When the temperature starts to decrease, the sensors will send a signal to the control unit - 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 is closed, 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 second heat exchangers.

Why the boiler does not heat well, does not pick up the temperature

No hot water? For what reasons does the technique not work? Sometimes it's about external factors. Let's take a closer look.

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

Airlock. Check for trapped air in the batteries. Remove excess air using taps. If you do not have an air vent on the radiators, then you need to install it. By adjusting its faucet, you can release the accumulated air in the system.

Also inspect the valve for blockage. Most often it gets clogged with scale.

Clogged radiators... After cooling down, drain the water from the pipes. If it is heavily dirty, run it over 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 and the shut-off valves installed?

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

Scale build-up in the heat exchanger. You can see that the technology heats up the liquid for a long time, the batteries are not very hot. Clean deposits from the radiator pipes. For this, it is better to remove the node, but this can not be done in all models. Therefore, remove the cover, 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 means can be picked up in the store. Then rinse the parts under running water.

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

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

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

Clogged filter... Another reason for poor heating of the batteries. The mesh filter becomes clogged with small debris, so it is periodically removed and cleaned under running water. In case of severe clogging or wear, it is better to replace the part.

Incorrect adjustment... Check the set values on the panel. Possibly chosen too low temperature therefore 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 capacity may not be sufficient for normal circulation. Adjust the settings.

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

Failure to comply with the slope of the highway... The problem is typical for systems with natural circulation, which is ensured by adherence to installation standards. According to the documents, the slope of the pipes for each running 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 DHW

The main cause of malfunction 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 chip off and block the passage to the mixer. We have described above what to do in this situation.

Flow sensor problems... The part works on the principle of a fan that 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 does not help to 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 items.

There are many reasons for malfunctions. The symptoms we described will help determine what problem has occurred in your circuit. Pay attention to the operation of the technique and compare with the indicated problems. If you cannot eliminate the problem yourself, contact a specialist.

Water heaters are used as the main or additional source of hot water supply in apartments and country houses. A complex device can fail for various reasons, breakdowns cause a lot of domestic inconvenience and require urgent elimination. Let us consider in more detail why cold water does not enter the water heater, for what reason the pressure may decrease and why there are difficulties with heating.

Water heater

Why the water heater does not work

First of all, you need to figure out the cause of the problem. Most often, the owners of water heating equipment are faced with the following malfunctions:

The water pressure at the outlet of the water heating equipment decreases.
The boiler collects water and heats it, but there is no water at the outlet.
Water does not enter the boiler tank.

A boiler is a complex system consisting of many pipes of various diameters, filters, valves and valves. Failure of any unit can lead to malfunction of the entire system.

Boiler design

Here are the main causes of malfunctions:

Precipitation of insoluble carbonate salts (scale) on pipe walls, valve parts or valves.
Ingress of rust particles.
Blocking the flow of water by an air bubble.
Failure of a valve or valve (jamming of parts).

First of all, you need to find the problem node. To do this, sequentially disconnect the parts from the inlet and see after which unit the water stops flowing into the system. When problem area will be found, you can start repairing.

Important! Any actions related to opening the casing of the water heater will void the right to warranty service. Only proceed to work if the warranty has expired. Otherwise, it is advisable not to violate the warranty rules, but to contact the service center.

Trouble-shooting

Having found the problem node, you need to start restoring the boiler's performance. The order of action depends on the specific cause that interferes with the normal operation of the device. Let's consider the most common situations.

Limescale clogging

Scale clogging up the water heater

Scale is a deposit of insoluble carbonate salts on the walls of water heating devices. She is found in teapots washing machines, water heaters.

The amount of lime scale depends on the hardness of the water. In regions with hard water, even after a year of boiler operation, the amount of salts deposited on the walls may be enough to completely block the lumen of the heating element tubes or significantly narrow it.

If scale has become the reason for the failure of the water heater, repairs must be carried out in the following order:

Open and remove the protective cover from the water heater.
Unscrew the nuts holding the heating element in place and remove it.

Dismantling the heating element

Wash the walls of the boiler and the heating element coil from carbonate deposits. Organic acid - lemon or oxalic acid - will help dissolve the hard crust. You can also use industrial means - antiscale. Soak the part in an acidic solution to loosen any accumulated deposits.

Cleaning the heating element from scale

Using a tester, make sure that the heating element coil has not burned out due to a violation of heat dissipation by scale.
If the coil is intact, assemble the device in the reverse order of dismantling.

If the heating element is out of order, you will have to look for a new one or buy a new boiler - you need to choose the most economical solution. If repairs require large financial costs, it is more profitable to immediately purchase new equipment.

Failure of the pressure reducer

The pressure drops of the incoming water in the system can be from 2.5 to 7 atm. To compensate for surges, a special unit is installed at the boiler inlet - a reducer. Its task is to ensure equal pressure at the outlet from the boiler and from the tap. If it fell due to the failure of the gearbox, it is necessary to adjust its operation or replace the broken part.

Low pressure in the main water supply also leads to a drop in pressure at the outlet of the water heating boiler or in instantaneous water heater... Unscrew the hose and check the pressure level: if water comes from the main water supply in a thin stream or does not come at all, it is worth waiting out, as the problem may arise due to renovation works... If the pressure has not recovered within a few hours, it is worth contacting Vodokanal.

Broken thermostat

If the water leaving the boiler does not heat up enough or does not heat up at all, the reason may be the failure of the thermostat - it is he who is responsible for maintaining constantly high temperature... To carry out diagnostics, turn off the power to the boiler and remove the thermostat from the housing.

Press the thermostat button.
Heat the copper tip of the thermostat. If the node is healthy, the button should be disabled.
Ring the electrical circuits of the thermostat with a tester.

Typically a thermostat malfunction is caused by an overheating protection trip. As a result of the operations carried out, the device should work, and the malfunctions will disappear after it is installed in place. If the tester shows an open circuit, you will have to replace the burned out thermostat.

Mixer clogged

If water comes out of the boiler with sufficient pressure, but runs slowly from the tap, the reason lies in the faucet clogging with scale or rust. You will need to turn off the water, disassemble the mixers and thoroughly clean the filter mesh. You should also inspect all rubber seals to ensure that the crane trailers are working properly.

If water does not flow into the boiler

If the described causes are eliminated, the water pressure is present, and the boiler still cannot be filled, the reason may be incorrect connection (inlet and outlet pipes are mixed up) or clogging of the mesh filter pad. Fixing these problems is easy: unscrew the hoses, rinse the filter and put everything back in the correct order.

Water heater operation diagram

Another reason for the malfunction is a breakdown. check valve... It is installed at the entrance to storage tank and prevents water from returning to the mains. It can also release excess pressure when it overheats. Over time, the valve spring becomes clogged with scale and rust particles, causing the valve to jam. Disassembly and thorough cleaning will help eliminate the problem. If it was not possible to clean the part and restore its performance, you will have to look for a replacement.

Having figured out why the boiler can stop working normally and how to eliminate the most common malfunctions, it is worth focusing on preventive measures.

Most breakdowns can be avoided by performing simple recommendations for care:

Do not overheat the water. Less temperature - the slower the formation of scale, leading to breakdowns.
Many boilers are designed to use softening cartridges. Do not skimp on water softening, as this will help avoid repair costs.
When leaving for a few days, turn off the device without draining the water. But turning it off at night to save energy is impractical due to the high wear and tear of the electrical part.

During the operation of a double-circuit gas boiler, each user will encounter certain problems associated with the operation of the hot water supply circuit. These problems are inevitable. They always appear, regardless of the manufacturer of the boiler and its heat exchanger, on the design features of the boiler; it does not matter whether the boiler is wall-mounted or floor-standing. Often the boiler starts to heat hot water poorly or does not heat it at all. Especially when you are using multiple points at the same time. Let's talk in this article on how to get rid of this problem forever.

In any room where a double-circuit gas boiler is installed, be it an apartment, Vacation home or office, there are certainly several places that are points water intake: washbasin in the toilet, shower in the bathroom, sink in the kitchen. All these points are connected to the hot water supply of the boiler.

What happens when hot water is turned on at one point of the intake

The double-circuit boiler is set to maintain a certain temperature in the hot water supply circuit. When you turn on hot water at one of the points:

for some time, cold water continues to flow from the tap, which was in the pipe before it was opened,
the boiler is heated, and it takes a certain time for it to reach the set temperature,
after a few seconds, the heated water enters the pipe and begins to move to the point of intake,
a few more seconds are needed for hot water to reach the intake point,
an additional few seconds are necessary due to the fact that the incoming water seems too hot to the consumer, and he regulates the water supply with the mixer.

Thus, at least a few seconds elapse from the moment the hot water tap is opened until the moment the water at a comfortable temperature begins to be dispensed. The farther the water intake point is from the boiler, the longer this period of time.

All this time, the user cannot fully use the water and it will be that the boiler does not normally heat hot water. He waits for the moment the water arrives at a comfortable temperature. Meanwhile, the water, which is not at a comfortable temperature for the user, simply goes into the sewer system.

Unproductive water consumption can range from several liters to ten liters, depending on how far the water intake point is from the boiler.

What happens when hot water is turned on at two points of intake at the same time

The scheme becomes more complicated if, while using hot water at one point of the intake, it becomes necessary to turn it on at another point, for example: with the shower turned on in the bathroom, it became necessary to wash your hands in the toilet sink. In this case:

the rate of use of hot water increases sharply, its consumption increases,
a weak pressure of hot water appears;
the flow of cold water into the boiler increases,
a drop in the temperature of the boiler heat exchanger leads to the fact that the water temperature at the first intake point ceases to be comfortable,
a few seconds are needed to turn on the boiler automation for heating,
a few more seconds - so that both users can use water at a comfortable temperature at two points of the intake.

During this time, both users cannot fully use the hot water. She arrives intermittently. The unproductive consumption of water that is uselessly going down the drain increases dramatically.

What if one of the users turned off the water? In this case, the hot water consumption drops sharply. A temperature jump occurs on the heater of a double-circuit gas boiler. As a result, the temperature of hot water rises sharply at that point of intake, which continues to work. The user cannot fully use the water, it goes into the sewer until the boiler is automatically activated and the water of the required temperature begins to flow to the user in a stable mode.

Since such situations are repeated several times every day, the unproductive consumption of hot water increases every day. At the same time, one should not forget about the discomfort that users experience at moments of unstable hot water supply.

Ways to solve the problem

The problem can be solved in ways that require significant investment, for example:

use with a boiler,
purchase of a new boiler with a built-in boiler.

However, there is a method that is less costly, but very productive - inserting an electric storage heater into the hot water supply circuit. Moreover, for this purpose, any standard heater with a volume of 30 liters, regardless of the manufacturer, is quite suitable.

Use a water heater

A water heater embedded in the hot water supply circuit acts as a buffer tank. Its purpose is to equalize the temperature of hot water and smooth out possible temperature fluctuations. The storage water heater and the gas boiler heater are set to the same operating temperature.

Even if hot water taps are simultaneously turned on at different points of its intake, all users will receive water from the storage device at first. The time spent waiting for a comfortable water temperature is reduced. Waste water consumption is reduced.

Turning on and off the hot water supply at any point of the intake causes a drop in the temperature of the water leaving the gas boiler. However, this water enters the lower part of the water heater, and when it leaves the upper part, the temperature jump is completely smoothed out.

Connecting the water heater via ball valve allows you to switch to the usual system of gas boiler operation at any time, which can ensure uninterrupted hot water supply in the event of a water heater breakdown.

The use of a bypass jumper with a tap in close proximity to the boiler allows the boiler to be excluded from the hot water supply system. If the boiler is on maintenance, the use of an existing water heater will ensure the smooth operation of the hot water supply system.

Use expansive tank

V winter period when the boiler has a heating circuit, any switching on of hot water leads to the fact that it is turned off so that the hot water circuit can be turned on. During the summer period, when the boiler is not connected to the heating circuit, each hot water activation leads to the switching on of the gas boiler.

Often the user turns on the hot water tap just to rinse their hands. The boiler turns on or switches, hot water flows through the pipes. But the user may simply not wait for it, having washed their hands with cold water.

Meanwhile, frequent and useless switching on and switching of the boiler "eat up" its service life. A possible way out is to install a small expansion tank. It is installed in front of the water heater. In the presence of such a tank, at the first time after turning on the tap, hot water enters the pipe exclusively from the water heater due to the increase in pressure in the tank. Thus, in the case of a short use of hot water, there is no need to turn on and switch the boiler.

Use recirculating pump

The best option - the water heater is located in the immediate vicinity of the hot water intake points. The closer it is, the faster hot water enters the tap, the more efficiently it is used. If this option for installing a water heater is not possible, then it is recommended to install a recirculation pump.

The pump is installed between the water heater and the hot water intake points, providing a slow movement of hot water through the pipes. In addition, if you cut in a heated towel rail in this section, then it will perform its direct function at any time of the year, regardless of the operation of the boiler heating circuit.

The effectiveness of the proposed method

At relatively low financial costs, the installation of a water heater, expander and pump allows:

save up to 25 thousand liters of water per year if a family of four lives in the apartment,
use water of a comfortable temperature even in the case of simultaneous operation of several points of water intake,
reduce gas and electricity consumption,
extend the service life of the double-circuit boiler.

Reading time: 2 minutes

Gas boilers are designed to create a comfortable living environment. Double-circuit units provide the living space with warmth and hot water in the tap. But it happens that a working boiler does not heat water well 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 reasons and solutions to this problem.

How does the boiler work?

For a clearer understanding of the situation, you need to understand the principle of the boiler. Such double-circuit gas wall-mounted boilers like "Baksi" or "Ariston" are composed of several parts. 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, part of the smoke exhaust is responsible for the removal of combustion products outside the dwelling.

After starting the boiler, the pump is switched on, providing the required water level in the system, and the gas supply valve opens. The heat carrier moves in a heat exchanger, which is heated by the burner flame. The thermostat monitors the temperature in the room, temperature sensors monitor the readings on the supply and return pipelines. Also, readings of the pressure of the fuel, the coolant in the circuits, the presence of traction and combustion.

Depending on the user's settings, temperature sensors adjust 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 temperature of the heat exchanger has dropped.

This is provided so that the water does not boil 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 to the gas valve. The whole process will start over.
When you open the tap in the mixer in a double-circuit boiler, a flow sensor reacts, which informs the electronics about the need to switch the three-way valve to the hot water heating mode.

When you turn off the hot water tap, it switches back to heating mode. Some manufacturers provide for both heat exchangers to be heated with 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 the heating system and what to do with this:

airlock. It is necessary to inspect the heating system for the presence of air in the radiators. To eliminate this problem, you need to install an air vent. Its principle of operation is similar to that of an expansion tank, but it is able to maintain the pressure in the system. Using an air vent, you need to bleed air from the system. It is important to inspect the valve itself for the presence of mechanical blockage - the presence of scale is possible there;
corrosion in radiators. It is possible to determine the blockage of heating devices by draining the water from the system. If the water flowed out dirty, then it is necessary until visually clear water appears;
connection errors. Hot water may not flow if the diameter of the pipes is not the same as provided by the project or instructions. It is necessary to check the conformity 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 prolonged heating of the coolant and heating of the batteries. It is necessary to get rid of deposits and conduct boiler water treatment. To do this, you need to disassemble the boiler and dismantle the heat exchanger assembly.

Before that, 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. Then the parts are washed with water.

It is important to understand that the addition of chemicals to the coolant prevents and reduces the appearance of deposits on parts. But before using the reagents, you need to familiarize yourself with the boiler instructions, 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;

clogged filter. If the filter screens are clogged with mechanical debris, the radiators may also not warm up well. 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;
incorrect setting. First of all, if there is little or no heating, it is necessary to check the settings of the control unit. An insufficient temperature can be set and the gas does not heat the water;
malfunctions of pumping equipment. If the pump power is not enough to ensure good circulation, then it can shut down if it overheats. This can happen when the DHW circuit is turned on;
incorrectly selected heating devices... If the system has radiators with inappropriate heat transfer and design parameters, this can also lead to poor heating;
wrong slope of pipelines. This problem most often occurs in natural circulation systems. Normative documentation specifies that the slope of the pipes should be from 10 mm for each meter of the pipe. In case of non-compliance with these requirements, circulation may be disturbed and, as a result, there may be no heating due to the low flow of the coolant.

The boiler does not heat water for hot water supply

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

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

After all, scale has a structure that restricts the passage of the coolant, as well as taking away its heat. This is due to the thermal conductivity of the 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 deposits, blocking the duct completely, which leads to a complete cessation of the hot water supply.

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

Structurally, the sensor is a paddle device through which water flows, which is a condition for its operation, because it signals the presence of a flow to the electronics, which, in turn, starts heating the water again. It happens that the sensor becomes clogged, but it can be cleaned from the clogging without removing it.

The device is in the form of a cylinder and is located near the circulation pump. To start cleaning, open and close the tap near the sensor. If this does not help, then it should be unfastened and removed, cleaned by hand and reinstalled. 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 over to heating water for DHW from heating water for heating. The first reason for its breakdown may be clogging by corrosion products, which must be removed.

If this does not help, then the valve should be replaced. The hose system and filter may also be dirty. This malfunction is hardly noticeable on the heating circuit, but it will be more noticeable on the hot water circuit. It is necessary to clean these elements.

Constructive and modification solutions of modern gas boilers are aimed at smooth and efficient operation. The 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 supply and heating the room. To understand what is the cause of the malfunction, why the Ariston boiler does not heat hot water, you 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 collection of several blocks responsible for a specific functionality of the system. So, the gas block is responsible for the ignition and combustion of the burner, which allows the heat-conducting liquid to warm up, water is supplied in the water unit and the required pressure in the main line is ensured, the chimney block is thrown into environment combustion products, the control unit controls the operation of all boiler systems.

When the unit is started with the help of a pump, water is pumped into the system, passing through the pipes of the heat exchanger. As soon as liquid enters the water unit, the gas supply valve opens and the burner ignites. The process of warming up the heat exchanger body occurs uniformly and is controlled by temperature sensors.

Important! The heating cycle is controlled by sensors. When the water temperature drops to a certain temperature, it is the sensors that transmit an impulse to the control module to resume heating.

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

The main problems why the boiler does not heat water

More often, boiler malfunctions 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 are working, the device turns on, but heats the water weakly or does not heat at all;
the boiler does not start and, as a result, hot water is not supplied.

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

Before finding out the reasons for the malfunction of the unit, you should look in the operating manual, read the instructions and check the correct settings and connection of the device.

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

If all the 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 blockage in the heat exchanger tubes. The formed scale reduces its thermal conductivity, which forces the unit to operate with excessive consumption of the energy carrier. In this case, the optimal temperature regime even with continuous operation. Due to limescale deposited inside the heat exchanger pipes, the metal undergoes corrosive changes, which can lead to its rupture.
Defective pump. The circulation of the coolant can be stopped due to the accumulation of air, the so-called air lock in the pump. A second cause of pump malfunction may be the rotor, which is seized. A circulating pump that stops functioning can lead to overheating of the gas boiler.
Flow sensor stuck. Inside the boiler is a turbine-shaped sensor that resembles a small fan. When the turbine rotates inside the sensor, an electrical impulse is generated due to the fluid flow, which is fed to the control unit. Thus, the electrical system understands that it is necessary to warm up the coolant.
The 3-way valve is stuck. Such a malfunction will not allow switching the water supply from heating to DHW. A valve stopping can occur due to a 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 required pressure, the water supply valve does not open, which leads to the failure of the burner to ignite.

Possible nuances

There are many wall mounted gas boilers from various manufacturers on the market today. 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" - Italian trademark, which is reliable. The brand boilers are adapted to domestic engineering communications and operating conditions. The most common cause of malfunctions is hard water, which contributes to the formation of blockages in the heat exchanger and the circulating 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 poorly may be the equipment shutdown. This is due to the air pressure sensor, which, in the presence of a reverse draft in the chimney unit, sends a signal to the control board, which closes the gas supply valve to the burner.
"Vilant". German quality fully reflected in the units under this trademark. Since the device is of European origin, most often its heat exchangers suffer, which are clogged due to the inadequate quality of the conductive heat fluid.
Baksi is another representative Italian manufacturers autonomous heating equipment... He has simple and reliable boilers. The main reason why "Baksi" does not heat water, as noted by the maintenance specialists of such units, is a factory defect, which sometimes occurs in the model line of this company.
Arderia is a South Korean manufacturer. He provided for a certain algorithm for controlling heating equipment. Incorrect settings can be the answer to the question of why the boiler stopped heating water.
"Proterm" - subsidiary German firm"Vilent". 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 established itself with 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 to the problem

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

Important! When troubleshooting on their own before starting work, the unit must be disconnected from the power supply and the internal components must be freed from the coolant

If the heat exchanger is clogged, you can clean it with special fluids, or using proven home remedies for descaling. Subsequently, it is better to use filtering devices at the inlet of the coolant to the boiler.
If the cause is a faulty pump, disassemble it and inspect the rotor. If foreign particles are found that impede free movement, they must be removed. The filter should also be inspected for clogging.
When the water flow sensor has become the cause of the malfunction, it is necessary to remove the part inside which the turbine is located. If, when rotating with a finger, it begins to click or slow down in the direction of travel, this means that there are foreign particles in the body. An attempt should be made to rinse the turbine and clean each blade with a cotton swab dipped in cleaning fluid.
The three-way valve, if it has caused a boiler malfunction, must also be cleaned, and at the same time the gas hose and filter must be checked.
At reduced pressure, check all fittings and valves on the device, the pressure with which water flows out of the mixer. If there are no leaks, and the pressure is weak or absent, then a simple replenishment of water in the expansion tank will help solve the problem.

One of the main tips is to follow the operating rules and follow the manufacturer's recommendations. 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 service life of the autonomous heater.

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