When do you need a boiler cleaning?
As a rule, these are 3 situations:
- Preventive cleaning of the boiler every 2 years, with minimal costs.
- Cleaning is carried out as the heat exchanger is contaminated with soot and lime deposits. At the same time, the efficiency of heating and heating water decreases. You can call the wizard, but the option of self-cleaning is also possible.
- Heat generator failure. Unfortunately, this situation is not uncommon at the height of the heating season. Called a technician to fix the problem. He also cleans the heat exchanger from soot.
As you can see, the last two scenarios are unattractive for the owners of the house. They are associated with additional costs and discomfort. It is impossible to do without a master even if a condensing-type boiler with a burner of a special design is used for space heating. It is undesirable to repair such complex equipment on your own. The exception to this rule is if you are well versed in this technique.
Criterias of choice
The first difference between gas boilers is that, as a complete overview of gas heating boilers shows, there are boilers with an open-type combustion chamber, and there are with a closed-type chamber. In boilers with an open combustion chamber, combustion products are thrown into the chimney due to the draft that is present in it. Oxygen, without which the combustion process is impossible, is taken from the room in which the boiler is located. Before choosing a gas heating boiler, it should be noted that a boiler with an open chamber can only be installed in a room where there is good ventilation.
The coaxial chimney is a pipe-in-pipe design. Fresh air enters through the outer pipe of the chimney, and exhaust gases are released through the inner pipe. When choosing a gas heating boiler, you should be aware that in the case of boilers with a closed combustion chamber, air comes from the street, so such a boiler can be installed even in an unventilated room.
Based on such a criterion as the removal of exhaust gases, models of gas heating boilers can be divided into the following types: parapet, chimney and turbocharged.
- A parapet boiler is a unit with a closed combustion chamber in which exhaust gases are released naturally.
- A chimney boiler is a unit with an open combustion chamber.
- Turbocharged boiler - is a boiler with a closed type combustion chamber.
Emission of exhaust gases in such boilers is forced. For the emission of exhaust gases, gas-fired heating boilers are equipped with a built-in fan.
How does a bithermic heat exchanger work?
Operating modes for heating and hot water supply have several differences. In the first case, the standard heating of water occurs in the process of gas combustion - if we are talking about the same gas boilers, for example. That is, in the heating mode, the heat carrier is directly heated, which then circulates along its circuit. As for the operation mode in the DHW format, this function is in some way secondary. The primary heating of the coolant also takes place, and heat is already transferred from it to sections with water intended for hot water supply. In this case, water for heating is not distributed through the corresponding circuits - it remains in its section. For almost all bithermic boilers, one rule applies - only one of the two circuits can work at the same time. Simultaneous circulation of water for heating and hot water is not allowed.
How to clean a gas boiler from scale Procedure
To disassemble the heating unit at home, you do not need any special tools. A set of home craftsmen with pliers, screwdrivers and keys is quite enough.
The algorithm of actions that allows you to effectively clean the heat exchanger of a gas boiler is as follows:
- Disconnect all wires from the gas valve.
- Remove the thermocouple from the combustion chamber. It is connected to the gas valve with a capillary tube.
- Disconnect the gas supply pipe.
- Remove the four nuts that hold the burner plate in place.
- Now it's the turn of the heat exchanger. To gain access to it, remove the top cover of the boiler, disconnect the chimney and the draft sensor.
- After that, carefully remove the insulation, and then unscrew the screws securing the casing and remove it.
- Under the casing is a heat exchanger. Remove the turbulators from it.
- Steel turbulators can be cleaned using a metal brush. And the heat exchanger itself can be cleaned with simple tools that are made by hand, in accordance with the dimensions of the fire tubes.
- After cleaning, mark the surfaces of the heat exchanger with a brush that is screwed to the handle.
- The last stage of cleaning is the cleaning of the bottom from soot, which crumbled during the cleaning of the smoke tube.
General information about the bithermic heat exchanger
Classic heat exchangers for boilers provide for the separation of heating chambers. That is, one chamber is intended for servicing heating circuits - as a rule, the main one, and for hot water supply - a secondary radiator. This design has many advantages, however, against the background of the combined heating chambers, its weaknesses become apparent. In this case, it would be wrong to assume that in the second case the water is mixed - such a principle does not allow a bithermic heat exchanger either. What is it in terms of approach to water maintenance? This is the same radiator equipment, but with a common housing, which contains both chambers for heating the coolant and compartments for preparing domestic water. In bithermic systems, the principle of separating the service areas of different environments also applies, but this applies specifically to the internal delimitation of the chambers. While the standard split heat exchanger initially contains two different chambers.
Advantages of bithermic aggregates
The advantages of single block heat exchangers extend both to the efficiency of heating as such and to the convenience of control, not to mention the higher reliability of the units. As for efficiency, bithermic radiators operate with a lower heat loss coefficient. If a system divided into two blocks requires heating of two blocks, then in this case the filling of one body is serviced - accordingly, the amount of heat generated increases. In terms of control, a bithermic heat exchanger is more profitable for the same reason. Thermostats are guided by the indicators of one solid block, which affects the accuracy of the data obtained. Reliability, in turn, is achieved by minimizing the connecting infrastructure - in fact, only a connection is required between the heat exchanger and the supply channels.
Types of gas boilers
According to the principle of operation, gas boilers are divided into two groups:
- convection;
- condensation.
The first group of boilers is considered to be traditional equipment that produces heating by burning gas, while part of the heat leaves with flue waste. The principle of operation of such a boiler is simple, understandable, and the price is relatively low.
The second type of boilers was developed according to new technologies, which make it possible to more fully use the heat of combustion of gas. This allows you to get an efficiency of about 15-20 percent higher than that of the convection model.And this means corresponding fuel savings and getting cheaper heat. However, it is significantly higher than that of convection.
Many European and world-class companies are engaged in the development and production of gas boilers. Almost all modern models are equipped with a reliable automated protective system that does not require manual control, which is responsible for supplying fuel and maintaining the temperature in a given mode. Models equipped with a gas pressure controller are guaranteed against overheating, fire, and other similar failures, as it will immediately stop the gas supply in the event of a pressure drop, fuel leakage, or flame extinction.
2013-01-23
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In many European gas boilers, a bithermic heat exchanger is installed. Judging by the assurances of manufacturers, this reduces the cost of production and practically does not affect the heat transfer and efficiency of heating equipment.
On the Internet, on the contrary, you can find many articles warning against buying boilers with a bithermic heat exchanger. To figure out where the truth is, you need to learn about the design features and operation of the device.
Secondary heat exchangers
A boiler for heating a house with a secondary heat exchanger is an equipment with stainless steel plates connected to each other. Such heat exchangers are installed in Linea, Mini kW, Major kW and Micra 2 boilers. These manufacturers think through the smallest details before deciding how to make a heating boiler. Such boilers are produced with a large heat exchange area, with high thermal conductivity of the plates, which ensures the necessary heat transfer even at a high coolant flow rate. Due to the flow rate, such a heat exchanger can “boast” of the absence of various hardness salts on its walls.
The design features of plate hot water exchangers differ in the direction of the flows of cold water and heat carrier directly towards each other. The power of such a heat exchanger depends solely on the number of plates that are interconnected. The more of them, the higher the power and the larger the heat exchange area.
Structurally, such heat exchangers are coaxial pipes (that is, one pipe located in another), on the surface of which heat exchanger fins are soldered - special copper plates.
The inner pipe is intended for domestic hot water, and the outer pipe is for the heat carrier in the heating system. When operating in heating mode, heat from the combustible gases is directly transferred to the coolant. When the boiler operates in DHW mode, the heat of the combustible gases is initially transferred to the coolant, and only after that to the DHW circuit. This stops the circulation in the heating circuit.
The disadvantage of this heat exchanger is one. In hot water mode, heat transfer is rather limited. Therefore, the amount of prepared hot water is also slightly lower than in boilers in which two heat exchangers are located at once.
In conclusion, it is worth saying a few words about heat exchangers, which are characterized by increased capacity. They are installed in original VIP class boilers - for example, such as Eura. By design, they are six-eight-liter boilers, inside which copper coils are located almost throughout the entire volume. Such heat exchangers are often also called mini-boilers.
A DHW circuit passes through the walls of such a mini-boiler, and a coolant circuit runs along the coil. The advantage of such a heat exchanger is that due to the large volume of coolant in the heat exchanger, when the flow rate and temperature of the DHW water change, the water temperature pulsations begin to smooth out right at the boiler outlet.In a word, hot water (with a stable temperature) is constantly provided at the outlet, regardless of changes in water pressure and temperature fluctuations at the inlet. In addition, heat exchangers with increased capacity allow you to use the function called "quick start", which provides hot water immediately after turning on the tap.
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Structural device
Now it’s worth understanding the design features of bithermic radiators, which allow it to separately heat different media. Specialists characterize such structures with the concept of "pipe in pipe" or "section in section". If a conventional heat exchanger assumes a set of pipes that have a hollow niche, then the bithermic device is distinguished by internal division into several segments - these are zones in which water for hot water and heating circulates without mixing. And already according to the classical scheme, copper fins-plates are also attached to the pipes, which increase the heat transfer coefficient. Obviously, depending on the method of integration into the target equipment, other design features of the radiator will also be provided. In particular, the design of a bithermic heat exchanger of a gas boiler is oriented towards heating by a burner, so the body can provide additional layers of protection. It is mandatory for all heat exchangers to provide means of ensuring safety against short circuits of electric current. Since the circuits can be interfaced with other utility lines, grounding and the presence of fuses in the boiler stations are also mandatory.
How does a bithermic type heat exchanger work?
The principle of operation of a boiler with a bithermic type heat exchanger is as follows:
- The plates accumulate heat and heat the tubes with the coolant circulating in them. The first circuit, the main pipe of the heat exchanger, is designed for pumping liquid for the heating system, the second (in the form of a rhombus), for hot water.
- The boiler operation algorithm is as follows - until the hot water tap is opened, only the heat carrier of the heating system circulates through the heat exchanger. As soon as DHW is required, heating for heating is temporarily stopped.
It turns out that double-circuit gas boilers with a bithermic design of the heat exchanger operate on the principle of alternate heating of the heating system and hot water, which allows more accurate use of the heat received from the burner.
The service life of the heat exchanger depends on several factors: the chemical composition of water for hot water supply, the wall thickness laid down by the manufacturer. A weak point and at the same time a disadvantage of bithermic heat exchangers is the susceptibility to sedimentation of scale inside the walls of the heat exchanger.
The heat generator with two separate heat exchangers will continue to work to heat the coolant after the DHW circuit is overgrown. The device of a bithermic heat exchanger of a gas boiler does not provide such an opportunity. After the overgrowing of the circuit, the operation of the boiler stops completely.
How and how to flush a heat exchanger with a bithermic design
There are several ways to flush:
- At home, the simplest method is to fill the boiler with flushing liquid and pass it through the circuit, using a booster pump that creates pressure. The procedure takes 15-20 minutes and does not require disassembling the boiler. The disadvantage of do-it-yourself repair is that some of the tools used are aggressive and improper performance of the procedure often leads to loss of tightness of the heat exchanger. Eliminating a leak between the circuits is quite problematic. A malfunction leads to the need to replace the heat exchanger.
- In the service center - the best service option that allows you to extend the life of the boiler and prevent its early failure. Aggressive chemicals are used during service only if it was not possible to restore throughput by softer methods.
There are several more recipes for flushing the heat exchanger: using acetic or citric acid, etc. Folk methods are ineffective and do not bring significant benefits.
Which heat exchanger is better - separate or bithermic
Two heat exchangers, working on hot water supply and separately for heating, are larger in diameter, therefore they grow longer and are less prone to calcium deposition on the walls.
When choosing between a separate heat exchanger or bithermic, one more factor is taken into account. The cost of the latest device is much lower. On average, the price per boiler is reduced by about a third. Low cost is the main advantage of the bithermic type heat exchanger.
If the heat exchanger is regularly cleaned, and a filtration and water treatment system is installed to feed the heating system and water supply, the bithermic boiler will last no less than an analogue with two separate circuits.
Boilers on bithermic heat exchangers
The use of bithermic radiators in boiler plants is becoming more widespread. Often, large manufacturers themselves develop model designs using their own components, including heat exchangers. One of the leaders in the segment is Immergas, which offers boilers with 6-tube heat exchangers. This design is a plus compared to 4 and 5 tube heat exchangers because the extended section can be located close to the burner flame. However, it is necessary to take into account the thermal power that the boiler will provide. The bithermic principle of operation in this case is capable of delivering about 24 kW, and this may be excessive for private houses and large country cottages. The companies Vaillant, Navien, Protherm are also developing bithermic units. The products of these manufacturers are distinguished not only by modern design, but also by functionality. Engineers strive to provide models with the ability to smoothly adjust the flame, the option of cooling the heat exchanger, etc.
Design flaws
The main disadvantage of the bithermic design is the limitation when working with liquids saturated with salts. In this context, one can note the imperfection of the monoblock case and the coaxial circuits inside, which are quickly covered with scale. In addition, a bithermic heat exchanger is not able to provide the same performance as in the case of split radiators. This applies specifically to hot water supply, since the design itself implies a smaller volume of water serviced for such tasks.
Gas boilers are popular among consumers due to their small size, easy installation and reasonable price. It is worth noting the ease of operation of this device and the availability of fuel to ensure the functioning of the boiler. Our store offers to buy any model from a wide range of gas boilers with a variety of characteristics.
Gas boilers can be installed in two ways:
floor mounting;
wall mounting.
The first option has larger volumes and weight, as a rule, due to the cast-iron heat exchanger. It is advisable to use such a boiler in private homes, where it is possible to equip a separate office space under.
The wall-mounted boiler is a compact equipment that fits perfectly into the interior of the kitchen, bathroom (if there is a window). Due to the high level of modern design, such a boiler will harmoniously look in any style environment.
According to the purpose and power of operation, a gas boiler can be single-circuit or double-circuit, single-stage or two-stage, that is, operating in one or two modes. A single-circuit boiler is used only for heating, but.
