Condensing boiler: details of installation and operation. Operating principle of a condensing boiler Installation of condensing boilers
The chimney is one of the most important parts in the design of a boiler room based on any boilers that burn fuel, including condensing ones. Proper design, material selection and high-quality installation chimney - necessary conditions long and efficient operation of the boiler room as a whole.
Main feature flue gases from condensing boilers is their low temperature compared to flue gases from traditional boilers. In turn, low temperature leads to the obligatory formation of a certain amount of condensate in the chimney. It is these two factors - low temperature and condensation - that are decisive when choosing a chimney material for a condensing boiler. In addition, the need to ensure constant removal of condensed moisture must be taken into account in the design and geometry of chimneys.
Against the background of the above, we will analyze three main aspects regarding chimneys for condensing boilers:
- Materials used;
- Design features;
- Basic installation diagrams.
Materials for the manufacture of chimneys for condensing boilers
The two most common materials used to make chimneys for condensing boilers are fire-resistant polypropylene and stainless steel.
Flame retardant polypropylene (PPs)
In domestic use, PPs chimneys are the most affordable and convenient in terms of installation. Generally speaking, polypropylene chimneys are also used with traditional boilers most modern designs, but still the service life in this case is limited due to the relatively high temperature of the flue gases.
In the case of condensing boilers, the exhaust temperature is low enough to have no effect on the strength of the chimneys. In addition, polypropylene is inert to the acidic composition of the condensate formed during the combustion of hydrocarbon fuels. That is, from the point of view of durability, this material is ideal for use with condensing boilers.
Another feature of chimneys for condensing boilers is the requirement for operation under excess pressure. That is, the connections of the elements must be sealed. Typically, silicone seals are used to provide a seal. Polypropylene is convenient here because, due to its elasticity, it does not require the use of additional clamps, unlike stainless steel.
The main disadvantage of this material is its vulnerability to ultraviolet radiation, that is, such chimneys cannot be laid outdoors in the open.
It is also important to note that polypropylene must be fire resistant. This fact is usually indicated by the letter “s” in the material designation (PPs). This type of polypropylene is more resistant to high temperatures and, no less important from a safety point of view, does not support combustion.
In past years, it was a fairly common mistake to use sewer pipes for chimney installation. pressure pipes from ordinary polypropylene in order to reduce the cost of the material. This should not be done under any circumstances for the reasons stated above.
Stainless steel
Acid-resistant grades of stainless steel are the second most popular material for condensing boiler chimneys in domestic use, and the main one in the industrial and commercial segment!
The basic requirements are still the same: operation under excess pressure and resistance to the chemical composition of condensate. In terms of temperature, stainless steel provides a huge margin of safety.
Types of chimneys
Three main structural types of chimneys, each of which has specific area Applications:
- single wall;
- double-walled (sandwich);
- coaxial.
Single wall chimney
From the name it is clear that these are simply pipes and shaped elements made of the appropriate material. Can only be used indoors or in thermally insulated ducts (for example chimneys during reconstruction). Typically used for the emission of flue gases when air is taken from the boiler room.
It is often also used to make a channel for supplying combustion air from the street. These air ducts, of course, do not have any special requirements for temperature and chemical resistance and tightness. That is, they can be made from almost any available material. However, from the point of view of uniformity and ease of installation, the same type of single-wall chimney is usually used as for the exhaust of flue gases.
Single-wall chimneys can under no circumstances be used outdoors. The main problem is the constant formation of condensation in the channel. From the point of view of chemical resistance, as noted above, this is not terrible, but there is a great danger of freezing of the liquid inside the chimney and, as a result, a narrowing of the pipe’s flow area. Fall natural traction due to the cooling of flue gases, this type of boiler is not critical, as they are equipped with powerful fans that provide a high value of residual pressure.
Double wall chimney (sandwich)
Elements of this type of chimney consist of two concentric pipes of different diameters, the space between which is filled heat-insulating material, usually non-flammable stone wool.
There are no special requirements for acid and heat resistance for the outer pipe; only resistance to atmospheric conditions (precipitation, ultraviolet) and mechanical strength. Therefore, in the case of double-walled stainless steel chimneys, the inner and outer pipes are usually made of different grades of steel to optimize cost. There are options with execution outer pipe made of aluminum.
Double-walled chimneys can be used both indoors and outdoors.
Due to the low temperature of the flue gases and the absence of the risk of burns, in the case of condensing boilers the double-walled option is usually carried out just outer part chimney, and for the internal one you can use a regular single-wall pipe.
Coaxial chimney
Again, based on the name, it is clear what this chimney is: two concentric pipes with empty space between them.
The main feature of this type is that it is used both for the emission of flue gases (through the internal pipe) and for the intake of combustion air (through the space between the pipes). Accordingly, when using it, it is not necessary to constantly ensure the supply of combustion air to the boiler room. In addition, the incoming air is heated from flue gases, thereby increasing the overall efficiency of the boiler room.
Laying coaxial chimneys is also only allowed indoors; the length of the external section in our conditions should be no more than one meter. A common problem in conditions cold winter is the freezing of ice at the end of the chimney. This happens due to the sharp cooling of the flue gases at the outlet upon contact with cold air entering the combustion through the gap between the pipes. To solve this problem, you can trim the area external pipe in the area at the end of the chimney to separate the exhaust of flue gases and air intake; or use factory ones winter options the end of the coaxial pipe.
This type of chimney is made from both plastic and stainless steel.
Basic installation diagrams for chimneys for condensing boilers
All chimney schemes for condensing boilers are divided into two main types: with combustion air intake from the room and from the street. Naturally, in the domestic regulatory documentation These types of smoke removal and the requirements for them are described, but the documentation for boilers usually contains names in accordance with European standards. A chimney with air intake from the boiler room is designated as “Bxx”, from the street - as “Cxx”. The first index varies depending on the specific circuit, the second - on the location of the fan relative to the boiler heat exchanger. In all modern condensing boilers, the fan is located in front of the heat exchanger, which is indicated by the index “3”. Below are the basic diagrams using the example of wall-mounted boilers:
For domestic power, chimney calculations are usually not necessary; it is enough to follow the boiler manufacturer’s recommendations for the maximum length, taking into account the shaped elements (elbows, tees, etc.). In the case of industrial boiler rooms, a smoke exhaust calculation is required; you can contact the chimney manufacturer for this.
Combustion air intake from the room
| The simplest way to organize the removal of flue gases. Almost always used for high-power boiler houses: industrial or commercial, when floor-standing boilers are used. It is also often found in household use. Two main requirements when using such schemes: ensuring the necessary air flow into the boiler room and its cleanliness. For large-capacity boiler houses this is usually not a problem, since these points are carefully taken into account at the design stage. In private boiler houses, a situation often occurs when sufficient air flow is not provided; or carried out through adjacent rooms, where after starting the boiler they continue finishing work, which contributes to the presence of fine dust in the air and clogging internal elements boiler Naturally, this state of affairs should be avoided or special air filters on boilers. |
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In this case, the chimney must be installed above the roof level and out of the so-called “wind surge” zone.
This is necessary in order to eliminate the influence of air pressure fluctuations on the smoke removal process.
Combustion air intake from the street
In this case, two main subtypes of chimney are used: coaxial and separate.
Coaxial chimney
As mentioned above, it is distributed mainly in domestic use with wall-mounted boilers. In a private house, a coaxial chimney is especially convenient in that it is quite easy to install it horizontally behind the wall, without constructing a vertical trunk extending beyond the roof level. This is possible due to the fact that the air intake and smoke emission areas are located nearby in the same pressure zone, and are thus not exposed to wind.
However, the issue of flue gas dispersion into the atmosphere remains. The emissions of modern condensing boilers are environmentally friendly, but the chimney must comply with standards for distances from windows, doors, ventilation grilles and neighboring land plots. In order to combine the convenience of installing a coaxial chimney indoors and using a double-walled pipe outdoors, you can use special transition kits.
In the case of modernizing an existing boiler room with brick chimneys, there is an option with coaxial pipe to the area of this chimney. Next, a new stainless steel pipe is laid inside it (single-walled can be used). Air intake is carried out through the gap between steel pipe and a brick chimney.
The most diverse option for organizing a chimney in terms of design options. However, it is rare in private construction and industrial boiler houses. Since for condensing boilers in the first case it is usually easier to use a coaxial chimney, in the second case it is easier to take air from the room.
Often found in apartment buildings with separate heat generators for each apartment, according to the following scheme: 
Regarding the selection and purchase of a chimney for a condensing boiler, please contact our
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The gas boiler has been purchased, the gas main has been connected, the heating has been installed, the most important thing remains - to assemble it all in unified system. Connecting a gas boiler is not so simple task, and it’s not even that gas boilers are high-tech equipment, and what’s most important is dangerous equipment, the main problem is different: too much various options and connection diagrams. The method, order of installation and connection of highways depends on individual conditions. Therefore, it is strongly recommended that the connection, start-up and adjustment of the gas boiler be carried out by an authorized service center. Besides, independent connection boiler will void the manufacturer's warranty. But situations are different, so in this article we will tell you the main ones. universal moments connection of gas boilers. Please note that the instructions for your boiler are of higher priority than any article on the Internet.
Gas boiler connection diagram
There are several schemes for connecting gas boilers. Which one to use depends on how the heating system is designed - open or closed, the coolant in it moves by gravity or with the help of a pump, has one high-temperature radiator circuit or several circuits, among which there is a low-temperature “warm floor”. Also important is the type of boiler - single-circuit or double-circuit, with an open combustion chamber or with a closed one, convection or condensation.
Connecting a single-circuit gas boiler
Single-circuit boiler equipped with only one heat exchanger, which heats water for one circuit. Initially, such boilers were used exclusively for space heating, but today they can be successfully used for hot water supply by adding an indirect heating boiler to the connection diagram. Single-circuit boilers come in wall-mounted and floor-mounted versions, which one depends on the power generated. Single-circuit floor standing boilers more powerful and heavier than double-circuit ones, they can be used for heating large country house and providing for households hot water.
The peculiarity of connecting a single-circuit boiler is that only two pipes with coolant can be connected to it - one will send it into the boiler for heating, and the other will leave it heated.
In the embodiment presented above, the coolant will circulate through the heating system of the house and return to the boiler for additional heating. Safety valve and an expansion tank are necessary to relieve excess pressure from the system.
This diagram shows the simplest way to connect indirect heating to a boiler - through a three-way valve.
Indirect heating boiler is a thermally insulated container containing water for sanitary needs. It is this water that we need to heat. For this purpose, a spiral-shaped heat exchanger is built inside the boiler, through which hot water coolant.
In this scheme, heating water for DHW (hot water supply) is a priority. When the sensor on the boiler is activated that the water has cooled down, the three-way valve is activated and all the coolant heated in the boiler rushes into the boiler. There it gives up its heat to the water and returns to the boiler for additional heating. The circulation of boiler-boiler-boiler will continue until the water inside the boiler is heated to the required temperature. After this, the three-way valve is activated, and the coolant from the boiler flows into the heating system and will circulate according to the boiler-heating-boiler circuit until the water in the boiler cools down.
The entire time the water in the boiler is heating up, no coolant circulates through the heating system. How long it takes to heat up a boiler directly depends on its capacity. For example, a 200 l boiler (for big family), filled cold water, heats up within 6 hours. But reheating this boiler will take 40 - 50 minutes. Heating a smaller boiler, for example, 80 liters, takes only 10 - 20 minutes. This time does not significantly affect the overall temperature in the house; in such a short period it does not yet have time to cool down.
Connecting a double-circuit gas boiler
It differs from a single-circuit one in that it has two heat exchangers: one is the main one, heats water for heating, and the second is additional, heats water for hot water supply. Most often, such boilers are a high-tech boiler room, in which everything is provided and automated, and are wall-mounted.
Pay attention to the photo, which shows the insides of a double-circuit boiler. 5 pipes are connected to it (from right to left): 1 - a pipe with coolant from the heating system, which goes for additional heating, 2 - a pipe with cold water, which goes into the heat exchanger to heat water for hot water supply, 3 - a gas pipe, 4 - a pipe with hot water for DHW, 5 - pipe with hot coolant for the heating system.
All automation of a double-circuit boiler is located inside. By default, the coolant heated in the boiler by the main burner is sent to the heating system and returned cooled back to the boiler. This is how the boiler-heating-boiler circulation occurs. But as soon as someone opens a hot water tap on one of the consumers, cold water begins to flow into the boiler through pipe 2. The three-way valve immediately redirects the coolant, and it does not go beyond the boiler, but the main heat exchanger circulates - an additional heat exchanger for heating water is the main heat exchanger. The coolant heats the water for domestic hot water while it is being used. As soon as the tap is closed, the coolant begins to circulate through the heating system again.
As practice has shown, a double-circuit boiler is not capable of providing a large amount of water for domestic hot water, no more than one consumer - a kitchen or a shower, and even then the water will not be too warm. The boiler simply will not have time to heat it to the required volume. That is why they are used only in small families, and for heating water in more add a boiler to the system.
According to the presented diagram, the coolant will only heat the water in the boiler, and the water supply system itself to the second circuit will be closed. This trick allows you to significantly increase the durability of a double-circuit boiler, which suffers greatly from harsh conditions. tap water. The additional heat exchanger for domestic hot water becomes clogged and fails in about a year. That is why the circulation of clean coolant in the secondary circuit is more economical option. But then what is the point of using a double-circuit boiler if you can install a single-circuit one of greater power? It will be both more profitable and practical.
Connecting a wall-mounted gas boiler paired with a conventional electric boiler as a storage tank for hot water is also possible. In this case, hot water from the boiler will flow into the boiler, and when its quantity decreases to a critical point (set automatically), the boiler will again heat water to fill the boiler. It is also possible that the boiler is filled with hot water from the boiler, and its further temperature is maintained using a heating element.
We have looked at universal connection diagrams for gas boilers; now let’s move on to the procedure for installing pipes and electrics.
Despite the fact that the diagrams above indicate where the inlet pipe is connected and where the outlet pipe is connected, be sure to read the instructions for your gas boiler. The location of the pipes may vary depending on the model and manufacturer.
First, a few words about the heating system itself. If it has already been used before, and now you are just changing the boiler, then you need to drain the coolant from the system and be sure to rinse it several times. Many different salts settle on the walls of pipes and heating radiators; so that they do not clog the fragile heat exchanger of the boiler, it is better not to be lazy and flush the system.
The heating system can circulate both water, so antifreeze. Is it possible to use antifreeze specifically with your boiler? Be sure to check technical documentation. Sometimes boiler manufacturers themselves recommend certain brands of antifreeze or even produce it themselves. You should not ignore such recommendations.
It makes sense to use antifreeze as a coolant in the heating system only if you live in the house on short visits and turn off the boiler when you leave for a long time. In this case, the water in the pipes may freeze, but the antifreeze will not. But if you live in the house permanently and do not turn off the boiler in cold weather, then it makes sense to use water as a coolant. The reason for this is the disadvantages of antifreeze: low heat capacity, high viscosity and coefficient of thermal expansion. For the entire system, this threatens that with antifreeze it is necessary to use a boiler and pumps of higher power, a storage tank of larger capacity and heating radiators of a larger area.
The use of water is also supported by the fact that modern gas boilers you can put it in safety mode, when the coolant cools down to +5 ° C, the boiler heats it up again.
The heating connection diagram to the boiler is as follows::
- Circulation pump (if necessary).
- Ball valve.
- Coarse filter.
- Ball valve.
Circulation pump always installed on the return line. Ball valves necessary in order to easily disconnect the system from the boiler without draining the coolant, as well as quickly remove the filter for prevention and cleaning. Coarse filter in the heating system is necessary in order to protect the boiler heat exchanger from clogging with salts, it is placed directly in front of the boiler, preferably on a horizontal section with the sump/catcher down. If it is not possible to install the filter on a horizontal section of the pipe, then install it on a vertical one. The direction of coolant flow must necessarily coincide with the direction of the arrow on the filter housing.
The pipe with the hot coolant coming from the boiler must be connected to the boiler pipe using quick release coupling“American” and also install a shut-off ball valve.
It is necessary to install ball valves on the inlet and outlet pipes with the coolant to drain the coolant from the system to summer period or for repair work.
Connection diagram for DHW to a double-circuit boiler:
- Coarse filter.
- Ball valve.
- Fine filter or magnetic filter.
- Ball valve.
- American quick connector.
To maximize the service life of the additional heat exchanger of a double-circuit boiler and protect it from scale, it is necessary to install coarse filters And magnetic filter. If a coarse filter has already been installed earlier - before the water meter, then installing it in front of the boiler does not make sense.
The outlet pipe with hot water must be connected to the pipe using an American ball valve; it is advisable to install a check valve.
All connections must be sealed with tow or FUM tape, or even better with a special plumbing paste.
Modern gas boilers come with two options for connecting to the electrical network - a cable with a plug for connecting to an outlet and a three-core insulated cable. Whatever option you come across, in any case you should adhere to this rule: the gas boiler is connected through an individual circuit breaker directly to the panel and it is imperative to take care of grounding. It is also advisable to use voltage stabilizers or backup power supplies in case of a power outage.
Automatic shutdown is installed near the boiler so that it can be easily and quickly turned off. Even if the boiler has its own cable with a plug, you should make a personal socket for it, to which power is supplied through a circuit breaker.
Ground The boiler cannot be placed on a gas or heating pipe. To ensure high-quality grounding, it is necessary to equip either a grounding loop or a point grounding. For the latter, there are ready-made universal modular grounding kits on sale (ZZ-000-015), the installation of which will take an area of 0.5x0.5 m in the basement of the house, underground or on the street next to the house. The resistance of the ground loop for a heating boiler should be no more than 10 Ohms. IN different sources You may come across other figures, but gas services require exactly these indicators - no more than 10 ohms. This is necessary for safety reasons and is due to the fact that power poles air lines for the most part they do not have re-grounding.
Gas boilers are different - some require a regular chimney, others require a coaxial one, and others ( parapet boilers) - not needed at all. Therefore, read the instructions for your boiler. Moreover, most often the gas boiler already comes with a chimney; it just needs to be installed correctly.
Rule one - the diameter of the boiler chimney must be equal to or greater than the diameter of the outlet pipe in the boiler.
Most often, the diameter of the chimney depends on the power:
- up to 24 kW - 120 mm.
- 30 kW - 130 mm.
- 40 kW - 170 mm.
- 60 kW - 190 mm.
- 80 kW - 220 mm.
- 100 kW - 230 mm.
Conventional chimneys extend upward, 0.5 m above the ridge of the house. They can be installed both inside the wall of the house, and inside the house itself or behind its wall. No more than three bends on the pipe are allowed. The first section of the pipe connecting the boiler to the main chimney must be no more than 25 cm. The pipe must have a closing hole for inspection cleaning. Boilers with conventional chimneys and an open combustion chamber require a large air flow; this can be provided either by an open vent or a separate supply pipe.
Rule two - the chimney must be made of roofing sheet or other acid-resistant material. The same goes for short sections, turning elbows and other things. The boiler must not be connected to the main chimney using corrugated pipes; brick chimney. As a result of gas combustion, steam is formed, saturated with sulfuric and other acids; during condensation, the acids precipitate and corrode the walls of the chimney.
Rule three - the coaxial chimney is mounted horizontally and discharges directly into the wall. This type of chimney is a pipe within a pipe. The inner pipe removes steam from the boiler, and the outer pipe carries air into the combustion chamber. This allows you to heat the air and increase the efficiency of the boiler.
The coaxial chimney should extend at least 0.5 m from the wall of the house. If the boiler is ordinary, then the chimney pipe should have a slight slope towards the street. If the boiler is a condensing boiler, then the slope should be towards the boiler - then the condensate will flow into a special tube - a siphon, which must be drained into the sewer. Usually in condensing boilers everything is described in the instructions. Maximum length coaxial chimney 3 - 5 m, the more turns or bends, the shorter the permissible length.
Rule four - parapet gas boiler is installed strictly according to the diagram near outer wall . The coaxial baffle is most often located at the back of the boiler, rather than at the top.
The gas boiler usually comes complete with all the necessary decorative wall linings, clamps and other elements.
Connecting the boiler to a gas boiler
As mentioned above, the boiler is connected to gas boiler to provide hot water supply. It can be connected to both a single-circuit and double-circuit boiler. There are several connection diagrams and those proposed below are only the most common.
This scheme has already been described above. A three-way valve is installed on the heating supply line, a pipe runs from it to the indirect heating boiler itself, where it is connected to the pipe using an “American” one. The pipe with the cooled coolant from the boiler crashes into the heating “return” line. For ease of use of the boiler, the outlet pipe must also be connected to the “American” pipe.
If the safety group, the pump and expansion tank are located directly in the boiler, such as in wall-mounted boilers, then the three-way valve is controlled by the boiler itself, to which a signal is sent from the boiler thermostat (must be connected).
If the boiler is floor-standing, then you can connect the thermostat directly to the three-way valve, then control will occur directly.
Connecting the boiler via an additional pump
This connection diagram also assumes DHW priority. It uses two pumps: one for the heating system, the other for the boiler circuit.
This scheme is used if the system has several circuits, for example, 1 circuit - radiator heating, 2 - circuit of the "warm floor" system, 3 - circuit of the boiler for hot water supply. The hydraulic needle and distribution manifolds allow you to evenly redistribute the coolant between the circuits. A more detailed diagram of the operation of the hydraulic arrow can be found in the video.
In addition to the proposed schemes, there are others - you can make the hot water circuit circulate through the system so that hot water always flows from the tap, and you do not have to drain cold water from the pipes. You can also use not just an indirect heating boiler, but a boiler with a built-in heating element for additional heating of hot water and many other tricks, which are best checked with a specialist.
Connecting a thermostat to a gas boiler
connects to a gas boiler in order to ensure more economical operation. The thermostat is installed in the most distant room or place where you would like to navigate whether it is time to “turn up the heat” or while it is still warm. This device will transmit information to the boiler automation that the temperature in the room has reached the lower permissible level, the boiler will automatically turn on and heat the coolant until the thermostat reports that the maximum temperature has been reached.
The thermostat must be positioned interior wall at home, 150 cm above the floor. The device should not be exposed to various heat sources, vibrations, drafts and sunlight.
In modern boilers for connection room thermostat special terminals are provided. Initially, the contacts are closed, as if giving a signal to the boiler that it is necessary to heat the coolant. Therefore, this jumper that closes the contacts must be removed. Then connect the thermostat to the terminals using a 0.75 mm2 two-core cable.
The gas service must connect the gas to the gas boiler and start the boiler, otherwise you will have to pay a hefty fine for arbitrariness. For reference, let us clarify that gas must be supplied with a steel pipe or corrugated pipe made of stainless steel with a diameter of 8 - 9 mm, also use a paranit gasket and tow for sealing. You cannot use rubber hoses with a metal braid, FUM tape, plumbing paste, etc.
It is the main element of the chimney system. Used on straight sections to achieve the required height.
There are three types of length sizes - 250, 500, 1000 mm. , which makes it possible to select elements in accordance with the design configuration. Chimneys of the “Sandwich” type consist of an internal welded pipe(various grades of steel (AISI 430, 304, 321) of different thicknesses and an outer pipe of larger diameter made of matte or polished (mirror) stainless steel AISI 430 with a thickness of 0.5 mm or galvanized steel. Between the pipes there is a layer of insulation - non-flammable insulating material based on basalt rocks.
Throttle valve
This is a chimney element used to regulate draft by partially blocking smoke channel, and also as a damper on an unused fireplace with an open firebox to prevent the outflow of warm air from the room through the chimney.
It is a pipe with a built-in butterfly valve and an outward handle.
Mono-thermo transition
This is a chimney element used when connecting chimney systems various types or if necessary, change the diameter of the smoke channel.
The transition is installed at the junction of parts of the chimney system with different diameters. As a rule, when moving from a smaller diameter to a larger one, in situations where several heat generators are connected to the main chimney channel at different levels
The outlet is the main element of the chimney system, which allows you to change the direction of the chimney in cases where it is necessary to bypass an obstacle, or turn the chimney in the desired direction. Bends are made from cylindrical sectors connected at a certain angle.
Tee 90°
Tee 90 consists of two cylindrical elements connected at an angle by spot or seam welding.
When installing a tee at the turn of the chimney from a horizontal or inclined position to a vertical one, a plug or condensate drain plug is installed at the bottom of the tee that closes the entire system.
It is preferable to use a 90° tee in dry mode, since when the flow of gases slows down during a sharp turn, active condensation may occur.
Tee 45°
A 45° tee consists of two cylindrical elements connected at an angle using spot or seam welding.
When installing a tee at the turn of the chimney from a horizontal or inclined position to a vertical one, a plug or condensate drain plug is installed at the bottom of the tee that closes the entire system.
The 45° tee provides better traction conditions than the 90° tee, since it has larger angle(135°) rotation.
This is a chimney inspection element designed to diagnose the condition of the smoke channel and clean the chimney by removing products of incomplete combustion of fuel (soot). The inspection makes chimney maintenance easier.
As a rule, the inspection is installed at the base of the chimney, below the connecting tee, as well as on horizontal sections of the connecting chimney more than 2 meters long.
The revision is a modification of a 90° tee equipped with a special cover secured with a pipe clamp. The revision consists of two cylindrical elements connected at right angles.
Stub
It is installed at the bottom of the tee to collect soot and condensation, and can also be removed to remove foreign objects from the chimney.
Plug with condensate drain
Designed to collect and remove condensate products from the smoke duct. Consists of pipe element, a conical element or a tray with a hole connected to each other. The hole is designed to drain condensate and is equipped with a pipe.
Conical end
If special-purpose elements are not installed at the mouth of the chimney, a conical end should be installed to protect the insulation from precipitation.
Thanks to the closure of the inner pipe and the upper edge of the truncated cone, the access of atmospheric precipitation to the insulation is blocked.
Used as the end of a chimney to protect it from precipitation.
Thermo-thermo transition
These are chimney elements used when connecting chimney systems of various types or when it is necessary to change the diameter of the smoke duct.
Transitions are installed at the junction of parts of the chimney system with different diameters. As a rule, when moving from a smaller diameter to a larger one, in situations where several heat generators are connected to the main chimney channel at different levels.
Must be made of materials with increased resistance to acid corrosion. It’s one thing when hot combustion products pass through a pipe, and quite another thing when condensation, a concentrated acid with a pH of 3 to 5, forms in it.
2. The chimney must provide free drainage of condensate into a special tank
This tank (boiler) must be equipped with a siphon seal filled with water to prevent flue gases from entering the drain pipe.
Insulated. Photo: Navien
3. It is necessary to provide for forced traction
The temperature of the flue gases is low (approximately 55 C), three times lower than the flue gases from a conventional boiler (180 C). Because of this, the natural draft of the chimney is usually not enough, so forced draft is used. The boiler fan helps remove flue gases from the boiler.
4. The chimney must be sealed
Due to forced draft, the chimney must be sealed along its entire length (for example, lip seals are used). Otherwise, some of the flue gases will enter the room.
Coaxial. Photo: Protherm
5. Constant air flow is required
For normal operation of a condensing boiler, it is necessary to organize a constant flow of air to it. This can be done in several ways, for example, by taking air from the room if there is a sufficient supply of it. If the supply air is not enough, the air supply is organized through the same chimney, which is usually made in the form of a concentric pipeline (coaxial chimney). Street air flows inside through the inner pipe, and flue gases are discharged through the outer pipe.
Compact boiler with coaxial chimney. Photo: Boris Bezel
6. It is necessary to correctly determine the length of the chimney
The length of the chimney cannot be arbitrarily large; it is determined by the fan power of a particular boiler model. For each condensing boiler model it is different, and is indicated in technical specifications products. For example, the De Dietrich VIVADENS MCR-P 24 model is recommended to be connected to a coaxial chimney with a horizontal ending and with diameters air channel 60 mm and for flue gases 100 m. And the length of this chimney should not exceed 6 m if it has a horizontal ending (the outlet section of the pipe exits horizontally through the wall of the house) or 20 m if the coaxial chimney has a strictly vertical design.
The editors would like to thank De Dietrich for their assistance in preparing the material.
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 is it?
A condensing boiler, including one running on gas fuel, is designed to solve the problem of replenishing a heated 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 the best boilers of 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, main feature condensing boiler - the use of energy released during phase transitions.
Pros and cons
Condensing boilers modern style do not forget about environmental problems. 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 showing 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 type boiler is more popular than the 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 are released into the atmosphere. Of course, optimal parameters are achieved only with proper installation and quality maintenance. Here a lot depends on the people themselves.
Operating principle
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;
- the use of internal parts of 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 boilers condensation type can only be obtained by 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 one. 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 is a whole series 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 strong winds and 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 are prime examples of such systems. The heat exchanger is made of stainless steel grades. The systems use a universal type burner, capable of using any type of liquid fuel.
Low emissions of harmful substances are due to the preparation of a mixture of fuel and air in ideal proportions. 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 outlet pipe into the sewer.
But it is important to understand that condensation inside the boiler does not clean water, 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 persistent substances - stainless steels 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 different 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 much high quality air.
Features of choice
The advantages of condensing boilers fully compensate for their individual weaknesses. 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 released heat allows you to increase the 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. Condensation of water released during combustion solid fuel, the effect is too small, 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, the boilers are able to operate at different temperatures air, 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. Bithermic 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 required power boiler, 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. The situation can be corrected 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, it is typical to use coaxial circuit. 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.
