Installation of a condensing boiler. Condensing gas boiler: features and advantages. Installation of condensing heating boilers

It's time to consider and understand the features of condensing gas boilers...

Condensing gas boilers: operating principle, types and advantages

Thanks to their high-tech design, condensing boilers make the heating system much more convenient, comfortable, and economical. If in conventional devices combustion products give off only part of the thermal energy, then in in this case this is done to the maximum. The Luch Tepla company presents a large assortment of boilers of all types.

Design

In their structure, condensing boilers are indistinguishable from typical heating devices. Available in several options:

1. wall-mounted (more traditional, focused on individual heating systems of private residential buildings);
2. floor-standing (high power, intended for use in office and industrial premises).

Their design includes a non-standard heat exchanger made on the basis of acid-resistant materials. Usually made of stainless steel or silumin. It looks like a pipe with a complex cross-section and spiral ribs. All this increases the heat exchange area and makes the gas boiler more efficient.

Besides, condensing device equipped with a fan positioned in front of the burner. It “sucks” gas from the gas pipeline, mixes it with air and directs it directly to the burner. The boiler also has an electronically controlled pump, which allows you to optimize heating power, reduce noise from the coolant flowing through the system and save on electricity.

Types of Condensing Gas Boilers :

There are several types of condensing boilers:

1. single-circuit;
2. double-circuit;
3. heating;
4. water heating.

Moreover, their power can vary from 20 kW to 100 kW, which is quite enough for household boilers. For office and industrial premises they are produced with greater power and in a floor-standing version.

Operating principle of condensing gas boilers :

In standard boilers, the escaping hot gases are simply released into the atmosphere through chimney channel, losing a significant share of unused heat. It is discharged outside along with waste products in the form of water vapor formed during fuel combustion. It is in the steam that additional thermal energy is hidden, which condensing boilers store and then transfer to the heating system.

As the steam cools, it condenses, that is, it becomes a liquid, and releases a certain amount of heat. This process takes place in a special heat exchanger with an expanded area. It is he who “takes” heat to transfer to the heating system. This approach was known before. But it began to be used relatively recently due to the advent of corrosion-resistant alloys, which form the basis for the production of condensing boilers.

Features of operation of CONDENSING gas boilers:

The operating efficiency of such gas devices largely depends on the characteristics of the heating system. The lower the water temperature, the more complete the process of condensation of water vapor occurs. Consequently, the higher the amount of latent heat that is returned to the system.

In this way, the condensation mode is maintained throughout the entire heating period. That's why the most important condition for the operation of a condensing boiler is the average temperature of the coolant. For example, at the entrance to the boiler it should be less than 60 degrees (ideally up to 57 degrees). This will give better condensation and increase the efficiency of the heating device.

But even if you combine a condensing boiler with old system, it will still bring tangible savings, since it will be more efficient than previous equipment. This is due to the fact that in our climate zone the coldest days in total occupy a little more than 10 percent of the duration of the entire heating period. On other days, optimal condensation is possible.

Advantages

Among the basic advantages of this type of boiler is high efficiency. In this case, it is equal to 108-109 percent, when compared with other boilers. Another advantage is their increased efficiency. It is approximately 15-20 percent more than that of standard heating devices.

E. Chernyak

So that the consumer remembers the boiler only during the scheduled Maintenance, it’s not enough just to choose quality and reliable equipment. It is important to install it correctly, because often illiterate installation leads to failure of the equipment and a ban on its delivery to warranty service. This is especially true when installing expensive condensing equipment

General principles

Collateral correct installation boiler and its further normal operation is the competent design of the entire heating system. The point is that, for example, significant efficiency and operating comfort of equipment cannot be achieved without installing thermostats. Modern technologies make it possible to create zoned heating systems. In this case, in each heating zone under sensor control room temperature its own microclimate is maintained.

The temperature of the condensation heat exchanger must be below the dew point of the exhaust gases, and the formation of chemically active liquid condensate on its surface is not only normal, but also necessary. Moreover, it must be diverted outside and neutralized in one way or another. Combustion product exhaust systems must be made of corrosion-resistant materials.

When installing systems with condensing boilers, it is important to accurately calculate the heat loss of the building and design heating taking into account the use of such equipment.

To reduce the required coolant temperature, additional measures to reduce heat loss are important - thermal insulation of enclosing structures, installation of windows with multi-layer glazing.

Boiler space

Guided by regulatory documents, a suitable premises is determined. At the same time, options for installing a boiler in bedrooms, bathrooms, and corridors are not accepted in advance. common use, rooms with insufficient ceiling height, small volume and lack of windows (transoms, vents). The most suitable places are a kitchen or a separate non-residential premises of sufficient volume with opening windows or vents (Fig. 2). The presence of sewerage in the premises is highly recommended.

Rice. 2. The boiler room must have opening windows

When hanging the boiler on the wall, you usually use the hooks included in the delivery kit. They are fixed to the wall using dowels. Then the unit itself is hung on these hooks. It is unacceptable if the upper edge of the boiler is further away from the wall than the lower edge, that is, in common parlance, “filled up.” For a traditional boiler, a forward tilt of 0.5-1.0 cm per 1 m does not pose a significant danger, but in the case of a condensing boiler the situation is different. After all, the condensation module is rigidly fixed to the frame. During boiler operation, condensation of water vapor from combustion products occurs in the secondary chamber of the module (economizer section). The resulting condensate is collected in a molded tray and discharged first into a siphon and then into the sewer (Fig. 3).

Rice. 3. Formation and removal of condensate from the condensing boiler module

When the top of the boiler tilts forward, the condensate flows into the primary chamber, comes into contact with the heat exchanger tubes and begins to evaporate intensively. This leads to the shorting of the flame control electrodes to the boiler body and its blocking.

Thus, when attaching the boiler to standard hooks, it is necessary to carefully check the verticality of the boiler and, if necessary, level it. The boiler tilting forward is unacceptable. Also, the boiler must not tilt to the side.

Deviations from the vertical position are checked using a level gauge.

Requirements for chimneys

Most errors when installing condensing boilers occur due to violation of the manufacturer’s recommendations or neglect of smoke removal standards.

Violations often occur due to the use of coaxial pipes or separate sets from traditional boilers. The materials for the manufacture of coaxial pipes of traditional boilers are aluminum alloys and steel. Their purpose is to withstand high temperatures of combustion products (110°C and above). The specificity of the operation of condensing boilers is low flue gas temperatures in standard modes (40 - 90°C), often below the dew point temperature (57 - 60°C, depending on the excess air coefficient). Condensation of water vapor from combustion products occurs not only in the boiler module, but also in the chimney. The condensate has low acidity at pH=4, but with prolonged exposure to aluminum or steel chimney ducts it can destroy them. Therefore, the chimneys of condensing boilers along the exhaust path are made of special polymers (for example, polypropylene) that are resistant to acid corrosion of condensate and can withstand temperatures up to 120°C. For example, the Baxi company (Italy) supplies plastic for its condensing boilers (Fig. 4), the efficiency of which is 108.9%. coaxial pipe with tip diameter 60/100 mm, length 750 mm. The delivery set includes: coupling and gasket; tip protecting against gusts of wind; decorative stainless steel trim for the outer part of the wall.

Rice. 4. Wall-mounted gas condensing boiler

The use of chimney kits from traditional boilers in condensing boilers and vice versa is prohibited.

There are also violations due to the use of sewer pipes as chimneys. Due to the rather high cost of special chimneys for condensing boilers, there is often a temptation to use sewer pipes, because low temperature flue gas is one of the features of such boilers. The mistake is that sewer pipes are not designed to last for long periods of time. high temperatures(80°C and above). And the temperature of the flue gases may be higher than this value, for example, when the boiler is operating in DHW mode. In this case, the sewer pipes are deformed, the sealing rings dry out and crack, and the chimney tract ceases to be tight. In this case, people's lives are at risk and damage is caused to chimneys due to their soaking from condensation and gradual destruction. In this regard, the use of sewer pipes as chimneys for condensing boilers is unsafe and is strictly prohibited.

Incorrect slope of chimney or air intake pipes. Options for installing chimneys of condensing boilers may vary depending on conditions (Fig. 5), however, the basic rule must be observed - the slope of the chimney pipe should facilitate the flow of condensate back into the boiler module. The slope of the air intake pipe should prevent precipitation from entering the boiler body.

Rice. 5. Options for installing chimneys in accordance with the European classification for type C boilers (with combustion air intake from the outside or from a common shaft)

In Fig. 6 are shown schematically the right ways organization of smoke exhaust and air intake during various types chimney pipes. So, in Fig. 6a shows the use of one chimney pipe and the transfer of the boiler to operation with air intake from the room. The elbows (if any) are assembled in such a way as to ensure that condensate flows through the pipe back into the condensation module. It is very important to avoid possible places with a negative slope, where stagnant condensation will accumulate and disrupt the operation of the fan.

As a special case, a single chimney is used, which exits straight up from the boiler without elbows. If you exhaust combustion products into an existing (or common for multi-story buildings) chimney (Fig. 6 b), then you need to make sure that this chimney can be used with condensing boilers and has a condensate collector with a siphon at the lowest point. The release of flue gases from condensing boilers into brick chimneys leads to their destruction due to soaking. Release into chimneys made of black steel or aluminum leads to increased corrosion. The most optimal are insulated chimneys made of polypropylene or stainless steel. If the customer has a chimney, for example a brick one, then it can be “lined” with polypropylene pipes or a stainless steel pipe.

When assembling the chimney, it is very important to follow the connection order: into a socket with an o-ring next section inserted from above with the smooth side. This allows condensate to flow back unhindered into the boiler module. But often stainless steel chimneys are assembled from scrap materials, and even with gross violations (the lower pipe enters the socket of the upper one), so condensate flowing back through the pipe exits through the connections, which in some cases leads to disastrous results. For example, condensate begins to flood the boiler.

When using a standard coaxial kit, it is also necessary to observe the upward slope of the chimney pipe (Fig. 6 c). For low-power wall-mounted boilers, the slope is ensured by the design of the end terminal - when the outer pipe is horizontal, the inner one has an upward slope.

Structurally, it is possible to install a boiler with a single horizontal discharge behind the wall. The slope, as in the above cases, is upward (Fig. 6 d).

Rice. 6. Options for organizing the correct pipe slopes

In Fig. Figure 7 shows diagrams of improper installation of chimney and air intake pipes. In this case, a stagnant zone may form, which interferes with the operation of the fan and leads to blocking of the boiler (Fig. 7 a). If installed as in Fig. 7 b or fig. 7v, condensate in large quantities flows out and freezes to form icicles. The location of the air intake pipe is as shown in Fig. 7 g will lead to atmospheric moisture entering the boiler body, and then to blocking the boiler or short circuit.

Rice. 7. Incorrect installation chimney slopes

Despite the fact that both the DBN and the recommendations of the manufacturer strictly regulate the distance from the emission terminal to the nearest objects, gross violations of these standards occur quite often. Among the most common are the low level of the coaxial terminal relative to the ground and the short distance between adjacent terminals.

The first is typical for private cottages. So, for the boiler and related components heating systems (pumps, collectors, expansion tanks, boilers, etc.) most often allocate semi-basements. The choice is obvious and correct - useful living space is not taken away, all components of the system can be hidden and they will not interfere with the design of the premises. After all, placing a bulky boiler with piping and a hot water boiler in the kitchen is not a very aesthetic solution. And although the vast majority of adapted premises have chimneys and ventilation ducts, there is a temptation to save on the pipe and, instead of “lining” the existing chimney and installing a separate smoke removal and air intake kit, lead the coaxial pipe from the boiler directly through the wall. As a result, the distance from the ground to the terminal is often several times less than the regulated distance. This arrangement, in addition to being dangerous for people, also contributes to the active absorption of ground dust and sand into the boiler fan, and then their entry into the mixing path and combustion chamber. In the future, this can lead to malfunction of the boiler, its premature wear and failure.

The second violation is typical for cascade installation of boilers. In this case, the desire to save money often leads to a reduction in the required distance between terminals or the use of air ducts not intended for such installation. It is clear that without reconstruction of the chimneys it is prohibited to start such boilers and put them under warranty. Therefore, it is best to use kits offered by the boiler manufacturer. (For example, Baxi offers not only chimneys for cascade installations, but also hydraulic accessories and control automation).

Before installing the boiler, it is also necessary to take into account the minimum distances from the flue terminals to the nearest obstacles.

Condensate drainage

The technology by which condensing boilers operate involves the formation of condensate from water vapor contained in combustion products. Depending on the temperature conditions and the power of the installed boiler, the formation of up to 50 l/day is possible. liquid that needs to be discharged into the sewer. The low acidity of the condensate allows it to be drained into the nearest siphon of household waste, which has high alkalinity. The neutralization reaction causes no harm environment. But still, the condensate drainage path must be made of materials resistant to acidic environments (polypropylene, PVC).

Among the installation errors is the drainage of condensate to the street. Installers sometimes lead the corrugated pipe directly to the street, similar to a split air conditioning system. IN winter period this will lead to blocking of the duct with ice, filling the module with condensate and the boiler going into emergency lockout.

If the sewage level in the house is located significantly higher than the boiler, it is necessary to use special condensate pumps with built-in reservoirs, for example Conlift units (Fig. 8), offered by the Danish company Grundfos. They will allow, as condensation forms, to raise it to the desired height and drain it into the sewer.

Rice. 8. Conlift condensate removal unit

Security group

Some models of condensing boilers do not have a built-in expansion tank and safety valve. Therefore, they must be installed during installation. Also in this case, a system filling tap should be provided. It should be located on the supply line after the boiler to prevent cold make-up water from entering the heated heat exchanger of the boiler.

In addition, the following errors occur when installing condensing boilers (typical of traditional heat generators):

• heating system wiring and boiler piping with small diameter pipes;
• incorrect gas supply (narrowing of the gas pipeline, use of an inappropriate gas meter for boilers, lack of gas filters or their illiterate installation, etc.);
• installation of boilers on wooden and other flammable walls without prior protection;
• lack of filters on the boiler return line and at the cold tap water inlet;
• errors in the organization of power supply (there is no voltage stabilizer or relay at the input to the boiler, there is no grounding loop, generators or other power sources are used that do not have a zero phase or produce distorted characteristics, for example, non-sinusoidal voltage).

Connecting the thermostat

A modern energy-efficient heating system is impossible without installing thermostats. After all, as we have already noted, condensing boilers operate most efficiently at low temperatures. And thermostats allow more precise control gas valve boiler and maintain the coolant temperature at the lowest possible level.

The indoor air temperature regulator CR4, manufactured by Honeywell (USA), uses the OpenTherm digital communication protocol to control the boiler (Fig. 9). This technology means remote control of the burner, in which the boiler produces exactly the amount of heat that is currently required in response to a proportional request from room thermostat. The digital connection used is noise-resistant and protected against incorrect connections and short circuits. Low ones are used safe voltages. The OpenTherm communication protocol can be used with boilers from various manufacturers.

Rice. 9. Boiler control using a thermostat with a radio module

The CR4 thermostat can be set to a 7-day heating and hot water program. There are 3 adjustable temperature levels and 5 factory heating programs. Provides display of boiler operating modes and fault diagnosis. There is frost protection.

Radio frequency communications are carried out using the band 868.0-868.8 MHz. Communication range: 100 m in open space, 30 m in a typical residential building. The receiving module is installed next to the boiler or inside it and is connected using a two-wire wire.

The advantages of remote control using radio communication are that there is no need to lay cables during installation, which is especially important when reconstructing heating systems.

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From the design instructions for condensing Buderus boilers(Germany).
Compliant SNiP 41-01-2003 clause 6.4.1 PIPELINES : "...Polymer pipes used in heating systems together With metal pipes(including in external heat supply systems) or with devices and equipment that have restrictions on the content of dissolved oxygen in the coolant, must have an oxygen permeability of no more than 0.1 g/(m3 ∙day)..."

VITODENS Gas condensing boilers
Design instructions

Bosch Condens 3000W
- Possibility of direct connection to the underfloor heating system

Other model
BoschCondens 5000 W Maxx
Possibility of direct connection to the underfloor heating system
Without required minimum flow circulating water

High-quality components such as a plasma-cured aluminum heat exchanger and robust construction make the Condens 5000 W Maxx not only extremely reliable, but also extremely durable. Thanks to innovative Flow Plus technology there is no minimum value of water pressure through the heat exchanger . For this reason, complete hydraulic system not required.

About the anti-diffusion layer (oxygen barrier):
"... This result once again confirms the fallacy of the widespread statement: “Pipes of small diameters do not necessarily need to be reinforced or protected from the ingress of oxygen into the coolant, since the flow of oxygen through the wall of such pipes can be neglected.” Proponents of this point of view urge not to reinforce with aluminum and not to cover with an AVOH layer (anti-diffusion layer for PEX pipes). and small diameter PPR pipes. However, it is precisely these pipes that stand, for example, in front of steel panel radiators (steel wall thickness is 1.2 mm). Therefore, it is necessary to reinforce small and large diameter pipes with aluminum for heating systems. Moreover, for small-diameter pipes this rule is more important than for large-diameter pipes, where calculation and reference to a specific application scheme is necessary.
For example, with D = 2x10-11 m2/s (oxygen permeability of polypropylene) and ∆сО2 MAX = 270 g/m3 (approximate oxygen content in the atmosphere)
Q/V=1.9٠10-8/DN2 (g/s٠m3) or 1.6٠10-3/DN2 (g/day٠m3)
for DN20mm, we get 4 g/m3 of oxygen per day - in other words, the formation of 30 g of rust is possible. One meter of pipe DN20 PN20 (SDR=6) contains 2.2x10-4 m3; accordingly, through this linear meter of pipe a maximum of 8.8x10-4 g/day will pass into the coolant. oxygen.
For example, if the heating system is made of polypropylene pipe PN20 (unreinforced or fiberglass reinforced), the volume of the heating system is 100 l, there is a wall-mounted boiler with an aluminum-copper heat exchanger and a heating temperature of 80 C ° and steel panel radiators, and the pipe capacity is 50 l, then per day for a typical set of pipes of different diameters with SDR=6 about 0.1 g of oxygen will pass into the coolant; in terms of per year this amounts to 37 g of oxygen, or 250 g of rust obtained in steel panel radiators(which will very likely leak after a year or two of use).
The scope of this article does not include an exact quantitative analysis of oxygen permeability, however, the given example allows us to resolve the frequently asked question: “How much oxygen does the plastic pipe? Is it a lot or a little? I think we have given a very specific answer. In conclusion, we note that many informative works have been written on this topic, but the conclusions of readers or companies supplying similar products to the market do not always correspond to the analysis carried out in these articles..."

Heating a house or other building has come a long way from its ancient prototype. There is no longer any need to throw wood or coal into the “insatiable” firebox. But in order to fully realize the benefits of modern equipment, you need to know this equipment well.

What it is?

Condensing boiler, including one operating on gas fuel, designed to solve the problem of replenishing a warm floor. The (relatively) low temperature of the circulating fluid makes it possible to cope with this task effectively. And also, according to suppliers, it is possible to reduce costs for the purchase of energy resources over a long period of time. If you turn to information materials from manufacturers, you can come across references to efficiency at the level of 108-100%. This seems to contradict the laws of thermodynamics, especially since best boilers other types have an efficiency of 90-95%.

The reason for this difference is that conventional gas-burning boilers do not involve an evaporation and condensation stage in their operation. The hot gases that pass through the heat exchanger in the condensing boiler do not fly away into the chimney, carrying away a useless few percent of the thermal energy. A solution to the problem was found in lowering the temperature of the flowing gases to 55 degrees. This temperature is equal to the dew point under normal conditions; when water vapor reaches this point, it condenses and releases thermal energy. So, the main feature of a condensing boiler is the use of energy released during phase transitions.

Advantages and disadvantages

Modern condensing boilers do not forget about environmental issues. The use of latent thermal energy avoids condensation. The peculiarity of the operation of these systems is the minimum amount of noise and comfort during use. But it is important to understand that a condensing boiler is more expensive than analogues of comparable power. A one-time substantial amount allows you to recoup your investment sometime in the future, but you should initially pay it in full.

In Western European countries, wall-mounted and floor-mounted condensing boilers are used very actively, because they calculate long-term consequences. In addition to being economical, equipment operating on this principle is characterized by increased safety. This option is supported by the built-in electronics system. Digital panels have no knobs or levers, but they work quite effectively. Some models are equipped with monitors that show technical parameters, which allows you to avoid rushing here and there, constantly checking the operation of the system.

Important: a condensing boiler operates normally only with an uninterrupted supply of gas or other fuel. It is not provided in all places in Russia, and residents of such territories, unfortunately, will have to abandon their decision.

Boilers consume approximately 70% less fuel than alternative designs. Wall-mounted boiler type is more popular floor-standing format. But the latter is distinguished by an increased variety of assortment and can warm up a larger area.

A condensing boiler differs from a conventional convection boiler not only high efficiency and energy efficiency. The low temperature of the exhaust gases determines such a difference as the possibility of constructing a chimney made of plastic. When using fuel, a minimum of harmful substances. Certainly, optimal parameters are achieved only with proper installation and quality maintenance. Here a lot depends on the people themselves.

Principle of operation

The condensing boiler works in such a way that the first heat exchanger is heated when fuel is burned, and the second takes heat from the burned gases. The walls of the secondary apparatus concentrate steam. But to prevent the condensate process from causing corrosion, manufacturers use excellent alloys. They are selected on the basis of chemical resistance.

To ensure that the secondary heating circuit collects maximum heat, solutions such as:

• attaching additional spirals;
• application internal parts various sections;
• installation of a condensing heat exchanger on the return path of the heating system.

It should be noted that the best results when using condensing-type boilers can be obtained only when using burners of the latest design. In them, the mixing of air and supplied gas is carried out strictly according to the optimal proportions.

Gas condensing boilers with a boiler can solve the problem of hot water supply even when using heating systems with a single-circuit profile.

There are three main options:

• embedding the boiler into the boiler itself;
• adding external tanks;
• the use of boilers operating according to an indirect heating scheme.

According to statistics, a built-in boiler with a capacity of 50 liters allows you to cover the hot water supply needs of a family of 3 or 4 people 100% without any difficulty. It should be taken into account that the presence of a tank narrows the consumer’s choice; structures with a volume of over 100 liters cannot be hung on the wall, even the strongest. It happens that the boiler is not initially equipped with a boiler - or even equipped, but its operation is not efficient enough. The solution to the problem is the installation of remote tanks. Compatibility with them is ensured for almost all wall-mounted gas appliances.

The pipes and pumps that provide circulation in such a system must be designed separately for heating and hot water supply.

The total capacity of the tank is selected according to the power of the boilers. If it is not large enough, heating the liquid will take a very long time or will not reach the required value at all. The standard approach to the factory settings of boiler automation implies the primacy of the heating vector. As soon as the coolant cools excessively, the sensor detects this and starts the heating unit.

To ensure that hot water remains at the same temperature level all the time, boilers with boilers are equipped with an internal heating element. The controller depends on the electrical supply and is directed by the automation of the boiler itself. A rather interesting question is whether it will be possible to use boilers for heating.

• Theoretically, this is possible, but there are a number of pitfalls. Most drives are equipped with heaters of only 1500 W. This is enough to warm up 10 square meters. m, but only with solid insulation and not too much strong winds
• , frosts.
• The heating element, operating constantly, will significantly increase the total electricity consumption.

You can push water through the system using standard piping, but it is not able to compensate for the weakness of the central link. It should be noted that condensing boilers are not only gas, but also diesel; similar designs Even many famous manufacturers produce them. The promised efficiency is slightly lower than that of gas-powered devices, but 98% is an extremely good figure. Viessmann Vitorondens 222-F and 200-T - vivid examples such systems. The heat exchanger is made of stainless steel grades. The systems use a burner universal type

, capable of using any type of liquid fuel. The developers managed to equip these devices with a comfortable control unit and sensor equipment. Heat sources can even be built into a completely fine-tuned heating system. Modern condensing boilers are almost always equipped with special casings that further reduce noise. Thanks to this, they can be used even in close proximity to the living space.

The device of the main components

Even a general acquaintance with condensing heating equipment shows that it is quite complex.

Its main components are:

• fuel combustion compartment;
• a device that supplies this fuel;
• a fan that improves mixture injection;
• original heat exchanger;
• cooling chamber, where the mixture of vapors and gases cools to a temperature of 56-57 degrees;
• condensation circuit heat exchanger;
• accumulator collecting condensate;
• a chimney through which cooled gases move;
• a pump that pumps water through the heating system.

The initial heat exchanger is tightly coupled to the compartment where the fuel burns. In this exchanger, the resulting gases cool down a little, but are still heated above the dew point. At this phase there are no special differences from the classical condensation scheme. Then the smoke mixture artificially moves to heat exchanger No. 2, which cools the gas mass to less than 56 degrees. The condensate, having shared its heat with the heated system, goes through the drain pipe into the sewer.

But it is important to understand that it is not pure water that condenses inside the boiler; it is saturated with inorganic acids. Since the temperature of the liquid is higher than room temperature, the aggressiveness of even a weak solution increases significantly. Therefore, designers try to use resistant substances - stainless steel or an alloy of silicon and aluminum.

To reduce the destructive effects of acids, it is recommended to install cast heat exchangers. A weld, even a very high-quality one, turns out to be an entry point for caustic substances.

Chimneys are also made from acid-resistant steel or plastic. Horizontal fragments of the gas passage must be directed at an angle. This solution allows you to redirect the water that appears during the condensation of water vapor back to the boiler. Since the gases leaving the condensation circuit lose their temperature, previously uncondensed moisture will inevitably be deposited on the walls of the chimney. It is known that heating boilers are required to produce varying amounts of heat depending on the time of day and weather conditions.

Adjustment is made using a burner; The modulating type makes this adjustment very easy. There are options with fixed power levels, and then the boiler automation simply gives the command to turn on less often. Most of the most modern devices still use modulated systems, which are considered more adequate and flexible designs. The amount of fuel consumption is determined primarily by the total power heating equipment and the load it carries. Condensing boilers are designed in such a way that they do not work well in high-temperature circuits and require too high an air quality.

Features of choice

The advantages of condensing boilers fully compensate for their individual weak spots. But in order to realize all their advantages, you need to take into account many subtleties when choosing. The latent heat released by condensation varies depending on the fuel used. If you use methane (in other words, natural gas), the heat released allows you to increase energy output by 11% compared to simple combustion. Liquefied gas adds 9%, and diesel fuel increases heat generation by 6%.

Other types of fuel - not only liquid, but also solid, add much less energy. It is the above types of fuel that are considered the most promising for use in condensing boilers. The condensation of water released during the combustion of solid fuel has too little effect, since it is achieved in a very complex way. Even among pellet machines, this approach is rare. By increasing the cooling of flue gases, energy extraction can be increased.

But the paradox is that when these gases lose heat, it will be more difficult to actually remove heat. The equipment is becoming more and more complex; the actual energy addition does not live up to expectations. In addition, boilers are capable of operating at different air temperatures and in different modes. And at the same time, condensation should be avoided in the chimney or in the boiler.

It is very important to choose devices with a minimum number of such phenomena.

Considering that convection boilers can only be regulated by the operation of the burner, it is advisable to choose options with the most complex burners and the units that control them. Bithermal heat exchangers cost less and are technically simpler. But such devices are much more demanding than usual in terms of the quality of the water passed through them. If it is not large enough, the tubes will very soon fill with a layer of scale. The efficiency of the system will inevitably decrease.

This danger is less common with separate heat exchangers, but they require the addition of:

• secondary heat exchanger;
• tap with three strokes;
• systems that control this crane.

The higher the required boiler power, the fewer auxiliary parts there should be. Anticipate their impact on practical work systems are extremely complex. First of all, as energy production increases, it is necessary to remove built-in expansion tanks and pumps with their surroundings. The most powerful boilers do not even have control systems. You can correct the situation by purchasing specially selected additional systems and units.

The latest innovation is pumps that allow you to adjust the rate of shaft rotation. Such a device immediately increases the cost of the entire system and complicates it. We'll have to install a more advanced controller than usual. Rarely is such equipment installed in the boiler itself; you almost always have to purchase it separately. Therefore, you will have to pay for both installation and more thorough setup.

Nevertheless, experts believe that the future belongs to these pumps. According to their estimates, by 2020 almost all new boiler models will be equipped with such systems. Chimneys in condensing boilers are already initially different from the usual models. In addition to the use of acid-resistant materials, the use of a coaxial circuit is typical. Most often, the two pipes in such circuits are made of plastic.

Important: coaxial chimneys cannot be longer than 5 m, which must be taken into account when choosing, as well as the preferred choice for the wall.