Why the boiler does not heat water

The main causes of malfunctions of water heaters

Many consumers, referring to the service center for warranty, ask the question. the boiler works but does not heat water the reason why? If the water heater fails suddenly, the causes of breakdowns can be hidden in the malfunction of one of the following parts:

  • To answer the question of why the water heater does not heat water, it is necessary to check the condition of the main working body of the unit. TEN, a tubular element immersed in the inner tank. The detail can have direct contact with water or installed in a special dry chamber. The work of the heating element is connected with the impact of extremely high temperatures, which over time leads to its burnout and failure. In addition to terminal failure, lime scale can deposit on the surface of the heating element, which reduces its performance.
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Diagnostics of water heater breakage https://www.way2location.com

  • The second reason why the water heater heats badly, can hide in the physical deterioration of the magnesium anode. The element is a rod coated with a special metal. magnesium, which is constantly in the aquatic environment and prevents corrosion of the internal surface of the tank by attracting solid particles.
  • If the temperature relay or sensor on the control panel burns out or fails, the heating regulation becomes impossible, and the water heater generates an error.
  • If the water heater has stopped heating, the cause can also be found in the wear of gaskets, oxidation of contacts, short circuits or leaking connections on the connectors.

The most likely reasons why the water heater does not heat water, hidden in the failure of the heating element. When any of the above problems are detected during equipment diagnosis, it is necessary to carry out repair or preventive maintenance for further normal operation of the boiler.


Below you can see the main steps to repair the water heater:

Gas boiler does not heat water. causes and ways to fix the problem

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

  • the first thing to do is to check if the air has accumulated in the radiators. It is necessary to remove air from the system with the help of taps. Install an air vent to avoid air leaks. The tap to vent the air from the battery

It functions on the principle of the expansion tank, without reducing the head in the system. After a long downtime of the unit check the valve, it can get clogged with scale;

Connect the pump hoses to the inlet and outlet with a filtration system and flush the heat exchanger with a special liquid for cleaning. After be sure to rinse the boiler with clean water to remove chemical residues, otherwise the remaining particles of the agent can lead to corrosion of the heat exchanger, pipes and heating batteries.

Heat Exchanger Flushing

Use of chemicals as additives for the coolant significantly reduces scale formation. But not all models are allowed to use antifreeze. Manufacturers Ariston, Arderia, Navien, Buderus, Viessmann, Electrolux prohibit the use of antifreeze, recommending the use of distilled water.

In the instructions to Rinnai, Baxi, Vaillant, Celtic, Ferroli, AOGV 11 6, Beretta, Bosch, Neva Lux, Protherm, Junkers, Koreastar, DAEWOO models it is allowed to use antifreeze. Please note that not all antifreeze is suitable for these boilers.

Ways to avoid the problem

Today there are many gas wall hung boilers from different manufacturers on the market. The principle of operation of units in all models is essentially the same, but each brand has its own nuances, which may be relevant to the causes of failure and, as a consequence, poor water heating.

  • “Ariston” is an Italian brand that is characterized by reliability. Boilers of the brand are adapted to local engineering and operating conditions. The most common cause of malfunction is hard water, which causes blockages in the heat exchanger and circulation pump.
  • “Navien” Korean autonomous gas boilers. They are easy to operate and efficient. The peculiarity of this modification is the presence of two heat exchangers and no control panel on the body. The reason why the boiler “Navien” bad heats hot water can be a stop of the equipment. The cause of these problems is the air pressure sensor, which sends a signal to the control board if there is a reverse draft in the chimney and the gas valve closes on the burner.
  • “Vaillant”. German quality is fully reflected in the units under this brand name. Since the device is of European origin, most often suffer from its heat exchangers, which are clogged due to the improper quality of the conductive heat-liquid.
  • “Baksi”. another representative of Italian manufacturers of autonomous heating equipment. It has simple and reliable boilers. The main reason why “Baksi” does not heat water, as noted by experts on maintenance of such units, is a factory defect, which is sometimes found in the model line of this firm.
  • “Arderia”. a South Korean manufacturer. It provided for a certain algorithm of control of heating equipment. Incorrect settings can be the answer to the question of why the boiler stopped heating water.
  • “Proterm”. a subsidiary of the German company “Weilent”. When operating these boilers, you need to monitor the quality of the heat transfer fluid, the use of cleaning filters to prevent clogging of the heat exchanger.
  • “Buderus”. another “German” in the domestic market of autonomous heating equipment, which has proven itself on the positive side. As with all Europeans, malfunctions can be caused by the formation of lime scale inside the heat transfer system, as well as clogging of the working fluid flow sensor.

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

Important! When fixing the problem by your own forces, you need to disconnect the unit from the power supply and free the internal nodes from the coolant before starting the work

  • If the heat exchanger is clogged, you can clean it with special liquids or by 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, you should disassemble it and inspect the rotor. If you find foreign particles that stop the free movement, you must remove them. The filter should also be inspected for blockages.
  • When the cause of the malfunction was the water flow sensor, it is necessary to take out the part inside which is the turbine. If it starts to click or brake as you turn with your finger, it means that there are foreign particles in the body. You should try to wash the turbine and clean each of its blades with a cotton swab dipped in a cleaning liquid.
  • The three-way valve, if it caused the failure of the boiler, should also be cleaned, and at the same time check the gas hose and filter.
  • If the pressure is low, you should check all the fittings and valves on the device, the pressure with which the water flows out of the mixer. If there are no leaks and the head is weak or absent, simply topping up the water in the expansion tank will help solve the problem.

No hot water from your boiler? What to look for and how to fix it.

However, there is a less expensive, but very productive way. tie-in electric storage heater in the hot water circuit. And, for this purpose, quite suitable any standard heater with a volume of 30 liters, regardless of the manufacturer.

In any case it will be useful to get acquainted with the technique of this class and the features of modern models. This knowledge will help to choose the equipment correctly and not to make mistakes during its operation.

In domestic boilers Baxi, Navien and Ariston for water heating burn gas, diesel and solid fuel, use electric heaters. For more complete use of energy resources potential the heat exchangers are improved. They make long passages of a complex shape to ensure the long stay of the liquid in the working area.

The current trend is compactness. Manufacturers offer gas boilers with square bodies of relatively small thickness. Some models, in terms of their aesthetic characteristics, are well worth placing in a prominent place.

The next feature is the introduction of automated control systems. They control the combustion process, change the modes of operation, taking into account the readings of temperature sensors in the street and in individual rooms. In case of overheating, the appliances shut down without any intervention on the part of the user.

It is necessary to consider carefully a situation when a gas boiler Baksi does not heat water. This occurs, for example, when the energy supply is interrupted. Appropriate checks can easily be carried out even without special training.

Circulation pumps, valves and other typical components and assemblies rarely fail. Their designs are designed to operate for many years without mandatory maintenance. In electronic schemes there are no moving parts at all. Breakdowns occur because of defects. When complying with the rules established by the manufacturer, the resource of modern gas-fired heating boilers is more than 10 years.

Voltage jumps in the power supply line can damage the electrical part of the equipment. To eliminate such effects, an external stabilizer is installed. Checking the grounding system comes in handy. This is the only preventive set of measures in this group of problems.

Much harder to protect against the most common cause of breakdowns of gas boilers. Limescale cartridges. That is what we will study in detail in this article. When heated, calcium and magnesium salts are converted to a solid state. It is these impurities clog the narrow technological holes in the heat exchangers. They also form a porous structure on the surface of electric heating elements. If the normal heat dissipation is disturbed considerably their casings are damaged.

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

Not heating DHW. causes and troubleshooting.

The most common reason why the DHW does not heat is the heavy buildup of limescale inside the heat exchanger. Scale not only narrows the water flow in the heat exchanger, it significantly reduces the water temperature.

The reason is the thermal conductivity of scale salts is many times less than the thermal conductivity of the metal of which the heat exchanger is made. The unit does not give (does not deliver) hot water, or it weakly flows, if a piece of scum broke off and blocked the flow of fluid.

Hot water does not come to the tap when the flow sensor does not work. It is a fan, which operates when water flows through it. The signal from it goes to the control board, it gives the command to heat water. It can be clogged and can be cleaned without disassembling it.

The sensor is a cylinder located near the circulation pump. To clean, simply open and close the faucet in front of the unit. If this procedure did not work, you will have to dismantle it, clean it and put it back in its place. If the sensor is not working, you will have to replace it.

If the three-way valve is defective, the unit does not produce hot water. The purpose of the three-way valve. to shut off the heating system when you open the tap with hot water. When the valve does not switch, the boiler continues to heat water for heating.

The cause of a faulty valve can be an elementary clog, such as a piece of rust. If the problem is more serious, replace the valve with a new one. Also, one of the simple reasons why no hot water comes out of the faucet can be a clogged gas hose or gas filter.

Three-way valve in sectional view

In heating it will not be so unnoticeable, but the temperature of water from the faucet will be felt more significantly. Clean the hose and filters. Some of the points listed above can also be causes of heating and hot water problems in wood-fired, electric, and solid fuel (TT) boilers, provided the design details are similar.

Causes of frequent gas boiler shutdowns

The boiler does not heat water to the desired temperature, if it constantly turns on and off without human intervention. Such a problem indicates both simple setup failures and serious problems:

  • How the unit works. Most modern units are equipped with an external temperature sensor that responds to changes in room temperature. Depending on the set minimums and maximums, the equipment turns on and off, and the gas boiler heats badly. The problem is easily solved by changing the limit settings on the thermostat, which are set by both the temperature limits and the intervals of switching on, idle. Too frequent tapping explains why the gas boiler does not heat hot water, heating works. Especially dangerous are frequent cycles in changing modes of operation for units with automatic ignition.
  • Malfunction of the device’s automatics. In this case, if an individual element fails, the entire system will be disrupted. If it is not immediately clear why the gas boiler does not heat water well, you should pay attention to the operation of pressure sensors, temperature, ignition, draft and other systems.

Programming module of boiler unit https://www.invoz.ru/upload/resize_cache/iblock/0d7/1500_1500_1/tsifrovoy_kontroller_kromschroder.jpg

  • If the intensity of the flame of the burner is weak and a two-circuit gas boiler does not heat hot water, the reasons may lie in the weak pressure of the main gas. In such situations you should contact gas service or management company.
  • In some situations, it is necessary to trace what power is set on the control panel regulator of the boiler equipment. If the indicator is too high, the coolant can overheat, heat exchangers automatically switch to cooling mode, and the gas boiler badly heats hot water for the next 15-30 minutes. If such an incident occurs regularly, you should reduce the capacity of the unit.
  • If there is a strong wind outside, the chimney may back draft because of the overturning air currents. In such cases, automatic triggers, the unit turns off, resulting in a gas boiler does not heat water. If it happens one time, it is not necessary to do anything, but if the situation is recurring you need to replace the deflector or lengthen the chimney pipe. According to the rules of arranging gas installations the chimney must be at least 0.5 m higher than the ridge of the pitched roof.

Scheme of tilting of air flows in the chimney https://1-teplodom.ru/wp-content/uploads/7/d/2/7d2595cbde4da2a6ccf34442232add93.jpg

  • The same occurs when too much condensate collects in the coaxial chimney and icing appears in severe cold weather. This makes it difficult to remove the exhaust gases, which explains why a two-circuit boiler does not heat the heating well.

If the unit is turbocharged and the air is supplied to the closed combustion chamber by a fan, it is an energy dependent device. In such conditions, when the boiler does not heat water in the faucet, the cause may be poor quality wiring of the cable core. When installing electricity in the boiler room, install a separate circuit breaker for the unit, check the resistance on the phase-zero loop and the RCD tripping threshold in case of short-circuit. If the boiler does not heat water, it is also worth checking the earthing of the boiler installation and the correctness of this operation.

Frost on the coaxial chimney https://i.ytimg.com/vi/lrcoxcwZIdk/maxresdefault.jpg

The video voiced the main causes of frequent equipment outages in the boiler room

Why the boiler does not heat water for 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 critical fouling of the heat exchanger.

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

It is also possible when a piece of salt deposit has come off, blocking the flow completely, which leads to a complete stoppage of hot water supply.

The next cause of the boiler not heating water is a malfunction of the flow sensor.

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

The device is shaped like a cylinder and is located near the circulation pump. To start cleaning you have to open and close the tap on the sensor. In case this does not help, it should be unhooked and removed, cleaned by hand and reinstalled. If this does not help, then the sensor is most likely defective and must be replaced.

The cause of 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 you open the hot water tap on the faucet. If the valve does not work, the boiler does not switch to DHW heating from heating water. The first cause of its failure can be clogged with corrosion products, from which you need to get rid of.

If this does not help, the valve should be replaced. It is also possible to contaminate the hose system and filter. This defect is barely noticeable on the heating circuit, but on the hot water circuit it will be more noticeable. You need to clean these elements.

How to fix it with your own hands

Before you buy a boiler, properly calculate the appropriate capacity for your room volume. If the problem is a bad draft, you need to clean the chimney, clean the chamber where the air supply comes from, directly the furnace chamber. If these manipulations did not give results, install the draught regulator.

In case of poor operation due to fuel, you should first carefully study the manual and clearly determine what exactly can heat your model. Buying a reserve for the heating period, first buy a small batch for a couple of days, and, having checked the quality, you can make a purchase for the season. If the cause is the volume of the chamber, make the charge incomplete.

Problems with the gas boiler “Navien” and methods of their solution

Boilers Navien. gas water-heating equipment from the manufacturer from South Korea, widespread among consumers in our country. When the heating boiler does not heat well, the reasons may lie in one of the following situations:

  • If the Navien equipment does not start, the problem could be the lack of electricity in the network or a faulty gas supply line. If such a situation occurs, it is worth checking the voltage, and if the reason is the gas supply, contact specialized services.
  • If the boiler has stopped heating hot water, you should clean the heat exchanger, following the algorithm described above.

The video tells how to clean the internal parts of the unit from scale

  • In the case where the internal parts of the unit are cleaned of scale and other deposits, but the boiler still does not heat, you need to look at the condition of the strainers, the performance and settings of the pump group, as well as to check the system for air lock formation. As a rule, when there is aeration, the device first gets the temperature, but then slowly resets it to its original values.

Navien Gas Boiler Equipment https://otoplenie-expert.com/wp-content/uploads/2019/03/kotel-gazovy-dvuxkonturny-nastennyy-6.jpg

  • If the boiler is not heating water, the causes may lie in a malfunction of the turbocharger in the closed combustion chamber. In such cases, you should check the fan, replace the bearings, clean the axle, and if necessary, buy a new device.

The video lists probable reasons why the boiler equipment does not heat water

Any water heating unit, which operates in the heating system, must be serviceable and sealed. If the boiler “Baksi” does not heat water or the same problem is identified for the equipment “Navien” or another brand, but when opening the lid tank leaks, you should look for the causes in the device itself. As a rule, the problem is solved by calling the service department on the warranty card.

When the gas boiler “Solly” does not turn on the hot water, it is necessary to further inspect its built-in circulation pump. If you find a solid deposit on the impeller of the device when you open the housing, it should be cleaned or the pump should be replaced.

Baxi Gas Boiler Equipment https:///upload/iblock/4ea/4ead7eb3e4d52cffa45b3b226c346cd6.jpg

In the video about the problems that can arise during the operation of the boiler Navien

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