Service life of outdoor gas boilers. The best gas heating boilers. Why do people prefer cast iron over steel?
Any heating equipment has its own lifespan. Therefore, when choosing equipment, we pay attention to the quality of materials, strength and place of production. Every customer wants their heater to last as long as possible. To do this, it is important to understand what the standard service life of gas boilers depends on. On average, he works 7-12 years.
What factors negatively affect performance and contribute to wear? How to prevent breakage? This article will help you understand how to choose and operate a gas boiler correctly in order to avoid rapid wear and tear.
What affects the life of a gas boiler
It is believed that the duration of the unit depends on its class. So, economy-class models serve on average from 7 to 12 years. In this case, the device is repaired as needed. Models of the middle class (middle price category), as the manufacturers promise, will work for 10-15 years.
Why is class taken into account? Because cheap devices use lower quality materials, mechanical control, often there is no display. They are not as efficient in operation and are not equipped with the latest features.
Boilers of the middle and highest price category are supplied with units made of quality materials. They have built-in sensors, automation, self-diagnosis and useful functionality. Electronic control and the presence of the display make the use comfortable. But at the same time, the price of these devices is often "wound up" on the name of the manufacturer.
For example, such well-known brands as "", "", "", are much more expensive than less well-known ones. This is used by dishonest firms that, instead of expensive components, use lower quality Chinese ones. As a result, you overpay, and the life of the premium boiler is the same as in the economy segment.
What factors should be considered
In addition to the class and price segment, other aspects also affect the duration of operation of gas equipment.
Heat exchanger material
Why is the service life of a wall-mounted appliance shorter than a floor-standing one? Perhaps the type of placement matters? No, just floor units are equipped with cast-iron or steel heat exchangers. For the same period of operation, their percentage of wear is significantly lower than that of copper radiators, which are installed in mounted boilers.
Copper is thinner than steel, and during operation it lends itself to oxidation and corrosion. Backlash in the heat exchanger can be soldered, but the unit will not last long. The average term of work is from 5 to 10 years maximum. Practice shows that copper radiators serve no more than 7 years, after which they must be repaired or replaced. They are more sensitive to the quality of tap water.
Wall-mounted appliances are less powerful than floor-mounted ones. This leads to constant operation at maximum power and rapid wear.
The type of heat exchanger also matters. An ordinary coil can be descaled on its own, and the boiler will continue to work. Bithermic radiators are not subject to cleaning, and the replacement of the node is almost equal to the cost of a new device.
Burner type
Gas appliances have two types of burners:
- Atmospheric - take air from the room to maintain the flame. Combustion products are discharged naturally with the help of traction.
- Supercharged or forced (turbocharged chambers) - clean air is taken from the street through a coaxial chimney. The power of the flame can be adjusted, the smoke is removed by a fan.
What about operating time? Forced removal of combustion products is more efficient. The boiler works with greater efficiency, which increases the efficiency and reduces the load on its units.
In devices with an atmospheric combustion chamber, a lot of soot accumulates in the holes and on the elements. As a result, the equipment spends more power to maintain operation, heating temperature, so the nodes fail faster.
Electronics and automation
Electronic models are equipped with control sensors, self-diagnostics and require connection to the network. Instability in the network, power surges lead to damage to the elements. We recommend installing a voltage stabilizer.
Operation features
The service life of heating equipment initially depends on the right choice. To do this, it is necessary to select the boiler, taking into account the characteristics of the room in which it will work, and the planned peak loads. It is recommended to choose a boiler with a power reserve of 15-20%.
Choose a room for the installation of equipment in accordance with the regulations. It shouldn't be damp inside. Corrosion quickly destroys the heat exchanger, so install an air vent to bleed excess air.
Install magnetic filters to prevent scale formation. They soften water by attracting heavy salts.
Also, the pressure affects the life span of the unit. To keep the performance stable, include in the expansion tank.
- Devices with steel and cast iron radiators have the maximum service life.
- Devices with forced draft burner are more efficient.
- With a voltage stabilizer, the equipment will last a longer time.
It does not depend on the manufacturer's forecasts how many years the boiler will work. Its maintainability is of great importance. Therefore, it is better to choose so that, if necessary, it is easier to find service centers and spare parts.
A gas boiler of even the simplest design works perfectly only if the components work smoothly. When the equipment is set up and debugged, the result is always perfect, the house is warm, and the equipment does not require constant attention from the residents. However, any device over time spends a resource of strength and reliability, therefore, maintenance of gas boilers is required with a complete check of the performance of the units of the unit, cleaning, adjustment, etc.
Do not trust the maintenance of gas equipment to a non-specialist. The first and most important reason is the preservation of the guarantee for boiler equipment. The manufacturer agrees to comply with the warranty obligations only if the installation and maintenance of the boiler equipment is carried out by one of the service centers with the appropriate license and permission to carry out installation and operational activities.
The main advantage of a service contract in a licensed service center is a guarantee of the quality of work performed and a reduction in operating costs over the period of operation of the boiler. Service workers are trained by manufacturers and are supplied with all the necessary diagnostic and repair equipment. This means that the visits of service workers will not be delayed, and the boiler will always be in excellent condition.
Breakdowns in a gas boiler can be due to a defect that was not detected during the standard production testing procedure or due to improper operation, lack of proper care, when accumulated problems lead to a breakdown. Warranty and post-warranty service protect against both problems, and the house is provided with high-quality heating for many years.
List of works
To understand what exactly should be cleaned, checked and adjusted in the boiler, with what frequency, it is enough to look at the instructions and technical documentation, which must be attached to the boiler upon purchase. These documents provide a complete list of components and elements involved in the equipment, maintenance requirements and the frequency with which to check the status, perform service and update settings if necessary.
It is absolutely impossible to focus on this information for self-cleaning of a gas boiler. This information gives a clear idea of what to expect from a service company with which to conclude a contract for the maintenance of gas equipment.
Works are conditionally divided into three groups:
- Regular work carried out before the start of the heating season and after it, preparing the boiler for summer inactivity.
- Capital service. Works carried out every few years and aimed at servicing elements with an initially long service life (flushing the heat exchanger, replacing seals and valves, maintenance of fans, etc.).
- Repair in case of breakage. The procedure for actions and mandatory work in the event of an emergency, breakdown or consequences of external factors.
Seasonal maintenance schedule
Before the start of the heating season, the boiler should be brought into proper working condition, the operation of the sensors responsible for safety should be checked. Only after that the boiler is switched on for operation.
If the manufacturer is allowed to carry out routine maintenance only once a year before starting, then in addition to commissioning, the main elements of the boiler are cleaned, with the exception of flushing the heat exchanger and a complete overhaul of the control units. If MOT (maintenance) is carried out after the season, then cleaning is assigned to this stage.
Required list of works:
- General inspection, removal of dirt from internal and external surfaces.
- Cleaning filters (air, gas, coarse cleaning for water).
- Cleaning and checking the burner.
- Cleaning the fire section of the combustion chamber.
- Checking the tightness of the internal gas channels.
- Checking the ignition electrodes (piezoelectric element and burner).
- Test and diagnostics of the electronic control unit.
- Test and diagnostics of sensors and automation responsible for safety.
- Boiler parameters adjustment, combustion adjustment. The process is accompanied by the analysis of off-gases. According to the composition and concentration, the master judges the accuracy of setting the boiler.
- Checking the condition of the shut-off valve.
- Checking the supply gas pipeline in the section from the main to gas equipment.
- Checking and adjusting the pressure in the expansion tank.
Overhaul
In addition to routine maintenance carried out every season, during the overhaul of a gas boiler, elements with a limited warranty period are replaced, the internal surface of the heat exchanger is cleaned, seals and valves are flagged. The main task is to replace elements that are not subject to maintenance during routine maintenance, but still have a service life.
In the event of a breakdown
In an emergency situation, when a breakdown occurs during operation, it is very important to react to the problem as soon as possible and return the boiler to working condition. Breakdowns, if they appear, then just in the heating season, for example, if the boiler operates for a long time at maximum power in the coldest period of the year. At this time, it is extremely difficult to find a specialist for a quick repair, but with a service contract, all you need is to leave a request so that the repair team arrives in a short time to fix the problem. Since the service center keeps records of boilers, a specialist already arrives at the customer with a set of necessary tools and spare parts for a specific model of a gas boiler.
How often
Without fail, routine maintenance is carried out before the heating season in order to check the performance of the boiler and its elements, if necessary, clean and adjust. The manual for many imported boilers also indicates the procedure for the conservation of equipment in the off-season to eliminate the risk of corrosion of materials and save the life of key components.
The terms of major service maintenance are set by the manufacturer, moreover, separately for each model range. Often flushing of the heat exchanger is scheduled for every fourth or fifth year of operation. However, the service center where the service contract is signed may change the terms, for example, based on the actual characteristics of the coolant or gas used.
Service organization selection
It is expensive for a boiler manufacturer to open a branded service center in each region of the country. Instead, existing maintenance firms are licensed to carry out the necessary work on equipment installed in the area of responsibility of the service center. Licensing implies a certificate for a certain range of work, full access to technical documentation for the manufacturer's products, the ability to obtain new boiler components for warranty replacement.
The information itself voiced determines the choice of a service center in which it is worth concluding a contract for servicing a gas boiler:
- It should be located in the same region or city as the house with the installed boiler in order to reduce the response time of service employees.
- The center must be certified by the boiler manufacturer.
- The presence of an agreement that clearly spells out the obligations and rights of the parties, indicating all the necessary work performed by the service center in relation to a specific model of the boiler.
The list of certified service centers is available on the manufacturer's website, and any visitor can see it. This is the best option to check the appropriate approvals and certificates with your local service center.
Heat exchanger BEFORE and AFTER flushing and maintenance average cost
Service centers usually provide the following options for cooperation:
- One-time visit for inspection and repair of the boiler, diagnostics.
- One-time maintenance of equipment during the first start-up or before the start of the heating season.
- Annual maintenance, including preparation for the heating season, optionally scheduled visits for inspection and diagnostics, as well as a prepaid visit in case of a breakdown.
The cost of each type of work includes payment to the employee, payment to the service center, as well as overhead costs. If the first two aspects are approximately the same across regions and depend on the model of the boiler, its capacity and manufacturers, then the overhead costs often vary significantly. It depends on the distance between the service center and the client, working conditions, the number of specialists in the center and many other factors, which introduces a large difference between the price tags of various service companies.
The table shows the average prices for various types of work, depending on the capacity of the gas heating boiler.
Basically, the table takes into account the maintenance of imported gas heating boilers by service centers with the appropriate certificate from manufacturers. Domestic boilers, both in acquisition and maintenance, are cheaper; spare parts are easier to find and replace. However, their main feature is simplicity and unpretentiousness, so you can’t expect comfortable heating or extensive functionality from them, in fact, as well as trouble-free service.
Heating for houses and apartments is inevitably associated with material costs. Consumers know that the price range for gas boilers, installation and service assistance is quite high. For this reason, many seek to minimize the cost of acquiring, installing and operating boiler plants.
But not very expensive gas heating boilers can be unreliable and lead to serious problems during the operational period, and, consequently, additional costs. In the worst case, inexpensive boiler installations can lead to the fact that the home will always be warm. That is, when choosing economical gas heating boilers, the principles of reasonableness should be used.
Economical gas-fired boilers
The most economical are Navien gas boilers, which have an efficiency close to 100%. The efficiency of an economical gas boiler, which has a premium class, has a maximum value of 94-96 percent.
The efficiency of a middle class gas heating boiler is much lower and is approximately 70 - 90 percent. As for the cost, the premium and middle class have a difference of almost half. For this reason, savings is a very tempting factor. But experts are not recommended to purchase very cheap Russian gas boilers. The whole problem is that in a few seasons the difference in cost will be neutralized. And in the next few decades, owners will have to overpay significant amounts for the operation and maintenance of a gas installation.
Fuel types: which one to choose
A kilowatt of thermal energy will cost depending on which type of fuel is chosen. It is a well-known fact that natural gas is the cheapest type of fuel. If your household has gas, then the question of choosing an economical boiler for space heating should not arise before you. If you do not yet have gas, but in the near future it will be supplied, then it is worth buying a double-circuit gas boiler. The systems can operate on diesel fuel as well as on natural gas. And during the transition from one fuel to another, it will be possible to avoid additional costs. Lemax gas heating boilers require only a burner change, and the installation itself will operate on gas.
Service life of gas equipment
Economical gas heating boilers have one very important criterion - service life. Economical gas boilers continue to live for about half a century, while middle-class equipment will last about 10-15 years. But it is important not only the service life itself, but also how long it can work smoothly. At the same time, it is directly related to the terms of the general operation. If you thoughtlessly save money and buy a low-quality Mimax gas boiler, then in a few years you may encounter an unpleasant need to repair or replace equipment in the midst of the heating season.
Boilers that run on gas can have two types of burners: atmospheric and inflatable. In an atmospheric burner, the process of formation of gas-air mixtures is carried out in a natural way. And in a pressurized or fan burner, gas is first pre-mixed with air, and then this mixture enters the combustion chamber. Economical Korean gas boilers have two forced-air burners. In fan burners, natural gas is burned more completely, which makes it possible to achieve the highest possible efficiency. This means that operating costs will be reduced by 25-30 percent.
Arrangement of a place for a boiler and gas equipment
If your house does not have an area of 350 square meters, then you can safely refuse to install an expensive chimney. After all, the cost of buying a gas boiler Ross and its installation can be about 100 thousand rubles. It is also not necessary to allocate a separate room for the boiler room in order to reduce the useful area of \u200b\u200bthe house. It is worth buying chimney-free economical gas boilers. They will help you save on installation, maintenance of the chimney, which will also not take up much space in the house.
Automatic type control system
Automatic boiler control
Economical gas boilers must be equipped with automatic control systems. Modern systems are very easy to use, they are reliable, they provide comfortable control of the temperature in the house, which, if properly configured, can save about 10-20 percent of fuel. That is, by reducing operating costs, the installation of a control system on a gas boiler will pay off in the first year and in the future it will help save your money.
Service maintenance
Unfortunately, among consumers who install autonomous heating systems for the first time, they try to save on service maintenance. Indeed, if you abandon it, you can save 10-15 thousand rubles a year. But even after one season has passed, the focus of the burner may shift, soot may appear, deviations in the operation of the automation and the pump from the passport mode may appear. The error of work, at first glance, is not great. But it leads to an unjustified risk, a decrease in efficiency, and in connection with this, the cost of operating a gas boiler also increases. It is worth saying that it is still worth saving when purchasing a gas boiler, but this must be done competently and carefully so that you do not have to regret it later.
Places for installing a gas boiler
Before you install the boiler, you should carefully approach the question of where it can be installed. It can be mounted on residential floors in separate rooms and on the basement, annex or basement. The area for installation of the boiler must be at least fifteen square meters, and the ceiling must have a height of at least 2.5 meters. A fire door with a third type must be installed. The walls must have a fire resistance of at least 0.75 hours and, in accordance with the design features, zero limits for determining open flames. In the room where the installation of a gas boiler is planned, a sewer pipe is laid, with a diameter of 5 centimeters or more. If the room is located on the ground floor or lower, then it is necessary to make a separate exit to the street.
Installation of a wall-mounted boiler
wall-mounted boiler
Due to its small size, the place for installing a gas boiler can be determined quite easily. Installation of a wall-mounted boiler can be done directly in the kitchen or in any other room. Wall-mounted boilers do not require free space and can be installed using wall mounts above other types of equipment or furniture that is located on the floor.
Installing a floor boiler
The installation of a gas floor boiler is as follows: a place is selected for installing a gas boiler, the pipes for chimneys are prepared to the outside, heating equipment is installed, connected to the water supply, to the electrical network, gas pipeline network, chimney pipe. The place where the boiler will stand must be flat and made of non-combustible material. All filters that are included in the kit, as well as pipes that must be installed in the process of connecting to the city gas service. When connected, a ball valve, a thermal shut-off gas valve, a gas meter and a room gas indicator are installed.
How to correctly install the boiler in the house
If you want to do the installation of the heating system yourself, then the installation of a gas boiler must be taken very carefully. Since, if even minor errors are made during installation, the consequences can be very serious, and you will have to spend a lot of money to eliminate them. Therefore, during installation it is better not to rush. All the main tasks should be carried out gradually in compliance with all stages. If we talk about what time the installation will have, then experts recommend installing the boiler in the summer.
Location of the floor gas boiler
If your choice would be stopped on a floor-type boiler, then you should immediately think about where it will be located. After that, it is required to bring gas pipes and mount a chimney. In order to comply with safety standards, the boiler must be installed on special stands. To do this, it is necessary to prepare a wooden formwork with a tedious area, pour a form a few centimeters high with cement mortar. The boiler can be installed on the podium after curing.
Chimneys
It is worth remembering that the chimney pipes must be carefully insulated. This is required so that the combustion products do not cool down in the chimney before they go outside. If carbon monoxide cools down in the pipe, it will lose its volatile properties and instead of the street, it will return back to the boiler, and from the boiler to the room.
Installing a wall-mounted boiler with your own hands
Installation of a wall-mounted boiler
If you want to install gas wall-mounted boilers yourself, then you need to purchase high-quality and reliable fasteners that can withstand the weight of the boiler. The place should also be chosen in advance, preferably closer to the bathroom or kitchen. After that, you need to carefully measure where the fasteners will be mounted. After this, the mounts are put on the mounts, proceed to the next installation step - run water and gas pipes. Don't forget to take care of quality chimney pipes.
During the installation of the boiler, you should definitely pay attention to the little things and details, as this is directly dependent on the efficiency and serviceability of the boiler installations. During installation, all nodes that are responsible for the security of the system must be connected, not only inside, but also outside. The main safety system includes protection against overheating, gas leakage, lack of smoke removal, as well as loss of electrical supply.
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A heating gas boiler is a device that, by means of the combustion of fuel (natural or liquefied gas), heats the coolant.
The device (design) of a gas boiler: burner, heat exchanger, thermally insulated housing, hydraulic unit, as well as safety and control devices. Such gas-fired boilers require a chimney to be connected to remove combustion products. The chimney can be either a conventional vertical or coaxial (“pipe in pipe”) for boilers with a closed combustion chamber. Many modern boilers are equipped with built-in pumps for forced circulation of water.
The principle of operation of a gas boiler- the heat carrier, passing through the heat exchanger, heats up and then circulates through the heating system, giving off the received thermal energy through radiators, underfloor heating, heated towel rails, and also providing water heating in an indirect heating boiler (if it is connected to a gas-fired boiler).
Heat exchanger - a metal container in which the coolant (water or antifreeze) is heated - can be made of steel, cast iron, copper, etc. The reliability and durability of a gas boiler depends on the quality of the heat exchanger in the first place. Cast iron heat exchangers are resistant to corrosion and have a long service life, but are sensitive to sudden temperature changes and are quite heavy. Steel containers can suffer from rust, so their internal surfaces are protected with various anti-corrosion coatings that prolong the “life” of the device. Steel heat exchangers are the most common in the manufacture of boilers. Corrosion is not terrible for copper heat exchangers, and due to the high heat transfer coefficient, low weight and dimensions, such heat exchangers are often used in wall-mounted boilers, but of the minuses, it should be noted that they are more expensive than steel ones.
In addition to the heat exchanger, an important part of gas boilers is a burner, which can be of various types: atmospheric or fan, single-stage or two-stage, with smooth modulation, double.
To control the gas boiler, automation is used with various settings and functions (for example, a weather-compensated control system), as well as devices for programming operation and remote control of the boiler.
The main technical characteristics of gas heating boilers are: power, number of heating circuits, type of fuel, type of combustion chamber, burner type, installation method, pump and expansion tank, boiler control automation.
To determine required power gas heating boiler for a private country house or apartment, a simple formula is used - 1 kW of boiler power for heating 10 m 2 of a well-insulated room with a ceiling height of up to 3 m. If heating is required for a basement, glazed winter garden, rooms with non-standard ceilings, etc. the gas boiler output must be increased. It is also necessary to increase the power (about 20-50%) when providing a gas boiler and hot water supply (especially if heating of water in the pool is necessary).
The peculiarity of calculating the power of gas boilers: the nominal gas pressure at which the boiler operates at 100% of the power declared by the manufacturer, for most boilers is from 13 to 20 mbar, and the actual pressure in gas networks in Russia can be 10 mbar, and sometimes even lower . Accordingly, a gas boiler often works only at 2/3 of its capacity, and this must be taken into account when calculating. In more detail with a table for calculating the power of a heating boiler, you can
Most gas boilers can switch from natural gas to LPG(ballooned propane). Many models switch to liquefied gas at the factory (check these characteristics of the model when purchasing), or nozzles (jets) are additionally supplied to the gas boiler to switch to bottled gas.
Pros and cons of gas boilers:
Boiler piping- These are devices for the full operation of the heating and water supply system. It includes: pumps, expansion tanks, filters (if necessary), manifolds, check and safety valves, air valves, valves, etc. You will also need to purchase radiators, connecting pipes and valves, thermostats, a boiler, etc. The issue of choosing a boiler is quite serious, so it is better to entrust the selection of equipment and its complete set to professionals.
What is the best boiler? The Russian market of gas boiler equipment has its own leaders in quality and reliability. The best manufacturers and brands of gas boilers are presented in the assortment:
"Premium" or "Lux"- the most reliable and durable, easy to manage, the kit is assembled as a "constructor", more expensive than the others. These manufacturers include German companies
Condensing boiler type
No matter how rapidly modern technologies of alternative heating systems develop, the gas type of heating remains the most economical and efficient type today. Its installation requires several permits from the relevant authorities, but the low cost of fuel, ease of operation and relatively uncomplicated installation, make this type of heating device one of the leaders in popularity.
Gasdouble-circuit boilers differ in the type of installation:
wall
floor standing
The difference is due to differences in design. floor version more powerful and heavier. It has a heat exchanger made of cast iron - a service life of up to 20-25 years. This material is quite sensitive to mechanical damage and thermal shock. Topping up the coolant must be done after stopping and completely cooling the circuit. With this in mind, manufacturers produce sectional, collapsible cast-iron heat exchangers for ease of dismantling and repair.
Steel heat exchanger. More resistant to damage and sudden changes in temperature, but susceptible to corrosion. Lighter and less expensive. Service life 10-15 years.
In wall-mounted boilers usually copper heat exchangers are used, which have a much higher heat transfer coefficient. There are additional benefits:
- Light weight and compact size.
- Relatively low price.
- Suitable for installation in apartment buildings.
Disadvantages:
- Short service life - up to 10 years.
- Low power - up to 65 kW.
- Sensitive to the quality of the coolant.
- It is not recommended to install together with aluminum heating radiators - it enters into a galvanic reaction.
By design type:
1. Single contour. They are used exclusively for heating the coolant in the heating system.
2. Double-circuit. They have an additional hot water heating circuit. Despite the fact that for successful operation in both modes, a double-circuit boiler must have more power, its installation is both financially and technically more justified than installing a single-circuit boiler and a separate boiler for hot water.
According to the method of heating water for hot water supply, double-circuit boilers are divided into:
Flowing
Boiler
Indirect heating boilers
Combined
Layered method of heating water
Flowing. Boilers of this type have 2 heat exchangers: primary - used to heat the coolant.
A variant of a joint unit with a full pre-mix burner is possible.
Secondary plate heat exchanger for domestic hot water. 
Recently, boilers with a bithermic heat exchanger have been produced. 
Technically, it looks like a DHW pipe with a figured section, located in a heating pipe.
This design provides a number of advantages:
- Reduces the size and weight of the boiler.
- When heating water for domestic hot water, the heating of the coolant is not turned off.
Disadvantages:
- Increase in cost.
- The small diameter of the tubes requires a more powerful circulation pump and reduces the flow of hot water or, with intensive use, its temperature.
- The entire heat exchanger must be replaced when scale is converted on the DHW pipes.
- When repairing the DHW, the entire boiler will be stopped.
Considering that most boilers with a DHW flow heating circuit turn off the heating of the coolant during its operation, a boiler-type system was developed.
Boiler rooms. A storage tank of 7-100 liters is mounted in the boiler body. which stores hot water. 
Advantages:
- Does not switch to water heating with little use.
- Hot water is always available.
- Providing hot water at the lowest pressure in the water supply system of 2-2.5 l/min.
- Large output of hot water up to 10-14 l/min.
- Possibility of simultaneous use from 5 points of consumption.
Disadvantages:
- Dimensions are larger compared to single-circuit ones.
- The price is higher than the flow ones.
All tanks in modern storage tanks are protected by a layer of thermal insulation to reduce heat loss and have an internal bactericidal coating or are enameled. The temperature control sensor turns on automatic water heating.
In turn, there are several technologies for heating water in a boiler:
Boilers of indirect heating. The water in the tank is heated through a coil, through which the coolant circulates from the heating system. 
Combined. In addition to the flow coil, they are equipped with an additional heating element .. it can be an electric heating element or a heat exchanger connected to alternative sources of thermal energy - a solar collector or a heat pump.
Layered method of heating water. The principle of heating water for hot water with this method is the supply of hot water from a flow plate heat exchanger to an insulated tank for further storage and use. Water supply and intake is carried out from above. To protect against corrosion, such tanks, in addition to the enamel coating, are equipped with magnesium anodes.
Advantages:
- Instant access to hot water.
- Small volume.
Disadvantages:
- The same as for flow boilers - corrosion and scale formation on the flow heater.
- Given the small size of the tank, hot water runs out quickly with heavy use.
Condensing boiler type
The principle of operation of such a boiler is to cool the hot products of combustion in a special secondary heat exchanger from 150 C to 55-58 C. During recuperation, the temperature that is released during the condensation of water vapor goes to heat the coolant or water for hot water supply, which significantly increases the efficiency of the heater.
Advantages:
Profitability. On average, up to 15% of fuel is saved.
Environmental Safety. Reduced emissions of harmful substances into the atmosphere.
High efficiency. Almost all manufacturers regulate the efficiency of products of this type at the level of 103-114%. Undoubtedly, this is just a marketing ploy, but its level is still the highest among all boilers with gas fuel.
Disadvantages:
High price.
It is necessary to additionally arrange drainage for the removal of aggressive condensate.
Features of the installation of double-circuit boilers
Before starting the installation, it is necessary to determine what type the combustion chamber is on the purchased boiler. If to open - combustion products are removed naturally through the chimney. In the closed type, a coaxial pipe is used and with forced ventilation. Such a pipe must be at least at a height of 220 cm and protrude from the wall at a distance of more than 18 mm. It is necessary to have a slight slope for dripping condensate, the outlet is closed with a protective grid. Obstacles in front of the extreme edge of the coaxial pipe must be at least 15 cm in front and 25 cm above.Brackets for wall-mounted boilers with a boiler must take into account the weight of the water in the DHW tank and in the expansion tank, if it is included as standard. For a floor-standing boiler, it is advisable to fill a special foundation of a small area with fixing anchors.
Before installing a new boiler in an old system, it is imperative to clean and flush the heating system, and completely clean the chimney. The pipe connecting the outlet system of the boiler with the chimney must be metal, resistant to aggressive liquids and temperature effects.
Boilers that do not have a boiler, it is not advisable to install further than 5-8m. from the hot water point of use.
Manufacturers of boilers of popular models
GermanyVaillant
One of the most reliable and popular manufacturers. Specializes in the production of heating equipment. The actual leader of sales in Europe. Last year, 2.7 million units were sold. It occupies 27% of the domestic gas heating appliances market. It has many model ranges of floor, wall-mounted, single and double-circuit boilers, of various capacities and wide functionality. The main difference and advantage over competitors is the high reliability of products.
At the moment, one of the most popular model ranges is eco TEC plus. 
Wall-mounted, gas, condensing, double-circuit boiler is designed using a number of patented technologies of the company:
The "hot start" function - hot water in the DHW system appears after 5 seconds.
Automatic increase in power when switching to hot water heating mode - APR (Aqua-Power-Plus) - the temperature of the coolant in the heating system does not drop.
The Aqua-Kondens system is used for primary heating of hot water.
The flame modulating gas burner allows you to adjust the power in the range of 28-100%.
The average efficiency for the heating season is 109%.
Small emission of harmful gases into the atmosphere.
Improved control and communication system - eBus.
Light weight (30-42 kg) and dimensions (720 x 440 x 335), power within the range of 15-45 kW.
Bosch
This brand has united several companies: Bosch Thermotechnology, Junkers and Buderus, which has 100 years of experience in the development of heating equipment. During this time, many technologies have been accumulated and improved. The last most successful model from the Bosh Condens 2000 series included the following improvements in its design: 
Bithermic primary heat exchanger.
Adjustable fan.
Gas burner with pre-mix technology, conversion to LPG without changing the nozzle is possible.
DHW temperature modulation and two ready modes: ECO - heating on command, COMFORT - constant availability of hot water.
Improved Bosch Cotronic 3 control module:
- Self-diagnosis of breakdowns;
- Frost protection;
- Protection of the pump from blocking.
- System of removal of thermal inertia from the heat exchanger.
Efficiency - 102.5%
Viessmann
Founded in 1917. The company specializes in the production of heating equipment. It has 23 factories in 11 countries. It supplies products to 74 countries of the world. The power range of the manufactured equipment is 1.5-116000 kW. The most popular models for home use from the latest Viessmann Vitodens range: 
The MatriX type burner has a long service life.
Heat exchanger Inox - Radial - made of stainless steel, resistant to corrosion processes, the original shape promotes self-cleaning from scale.
"Quick start" for domestic hot water provides an integrated storage tank of 46l.
Variable speed fan with low power consumption. Long-term operation from the 650 W BBP system is possible.
A wide range of manual temperature adjustments and several successful economical operating modes - “seasonal”, “shower”, “without a host”.
Italy
Hotpoint-Ariston
Leading company in Italy for the production of household appliances in general and heating equipment in particular. Ariston was founded in 1930. In 2007, it merged with the British company Hotpoint. The company's products have an ergonomic design. Since the merger, the company has taken a course to expand the functionality of products while simplifying the management process.
The latest developments in the field of heating technology are represented by the Ariston CLAS PREMIUM FF model range: 
The power of the boilers of this model range is 24-100 kW.
Efficiency - 110%, fuel savings up to 35% compared to boilers of the same functionality from other manufacturers.
Full adaptation to work in Russian conditions. Operating gas pressure from 5 mbar at ambient temperature up to -52 C.
Possibility of separate power adjustment of two circuits.
Stainless steel premix burner.
Continuous electronic flame modulation.
Automatic removal of air from a copper and all system of heating.
Semi-automatic water replenishment of the coolant in the system.
Protection against freezing and scale formation.
Both the main - spiral, and additional - plate heat exchangers made of alloyed stainless steel.
Three-way valve, hydraulic group, with motor drive.
Control panel with digital display, with self-diagnosis function, detailed log of emergency codes.
Biasi
Specializing in heating equipment. Founded in 1938. Thanks to its own iron smelting production lines, it has a closed type of production. That allows you to control the quality of products at all stages of the creation of units and assemblies. At the moment, it unites 7 factories and metallurgical plants. Offices are located in 40 countries around the world. All production is highly automated, which has a positive effect on the quality of products. A very popular model in the European and Russian markets BIASI PARVA CONDENSING NAT. 
The most popular models are 24 and 32 kW.
Efficiency - 92%.
Stainless steel heat exchangers with additional protective coating.
Heater NOx Class 5 with full premix.
DHW magnetic relay.
IPX4D auto protection level.
Ability to connect outdoor temperature sensors and remote control (not included in the standard package).
The presence of a large number of protective programs:
- Adjustment of the re-ignition frequency.
- Control of presence of the heat carrier in a contour.
- Protection of the circulation pump against jamming.
- Frost protection.
- Control of the chimney (coaxial hood).
Italian companies:
Beretta.
Immerges.
Baxi.
Nova Florida.
Hermann.
weller.
Feroli.
Fondital.
French companies:
Chaffoteaux.
South Korean companies:
Kiturami.
Navien.
Turkish companies:
airfel.
Demarad.
Ukrainian companies:
Aten.
Czech companies:
Protherm.
What you need to pay special attention to when choosing a gas boiler
With such a variety of different models, it is difficult to make your choice in favor of a particular one. But the price should not be the main selection criterion. For efficient operation, a modern boiler must meet a number of basic requirements:1. No Frost system that prevents freezing of the main components of the boiler, and in an improved form, the general heating system.
2. Advanced or universal type of burner - conventional ones are not very economical.
3. Basic equipment should include:
3.1. Membrane-type expansion tank with a volume of at least 7% of the total volume of the heating network.
3.2. Circulation pump.
3.3. A set of sensors for controlling the temperature of the coolant in the boiler, on radiators, and preferably an air temperature control sensor.
4. Boilers of foreign manufacturers must be adapted to the gas and electric networks of Russia.
4.1. The presence of an automatic burner on a piezocrystal or electric spark is mandatory. A burner with an incandescent element is desirable, which will make the operation of the boiler more economical and safer with low-calorie or unrefined fuel.
4.2. Products must be certified.
4.3. The operating pressure range of gas and water is preferably the widest possible.
4.4. Built-in surge protection system. Otherwise, you will have to buy and install an expensive filter. The ability to connect via a UPS with an output to an external battery is welcome.
Only after the presence of all the listed nodes and the fulfillment of the requirements, it is possible to compare the price of devices of comparable power.