Technological progress in the segment of heatingequipment develops in different directions. Some manufacturers rely on improving the performance of the element base of the aggregates, others promote the latest automatic control devices, and still others at the basic level are also engaged in the optimization of structures. The last group of developments includes a bithermic heat exchanger. What it is? In fact, this is a heating chamber, capable of performing two different tasks - to prepare water directly for heating, and for the needs of hot water supply, that is, for domestic consumption.
Bithermal Heat Exchanger Overview
Classic heat exchangers for boilersprovide for the separation of the heating chambers. That is, for the maintenance of the heating circuits, one chamber is intended - as a rule, the main one, and for the DHW - the secondary radiator. This design has many advantages, however, against the background of the combined heating chambers, its weaknesses become obvious. In this case, it would be wrong to assume that in the second case water mixes - this principle does not allow a bithermic heat exchanger. What is this in terms of approach to water service? This is the same radiator equipment, but with a common case in which both the chambers for heating the heat carrier and compartments for the preparation of household water are enclosed. In bithermic systems, the principle of separation of service areas of different environments also operates, but this applies specifically to the internal delimitation of chambers. While the standard divided heat exchanger initially contains two different chambers.
Construction device
Now it is necessary to understand the constructionfeatures of bithermic radiators, which allow it to separately heat different media. Specialists characterize such constructions by 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 ribs-plates are attached to the pipes, which increase the heat transfer coefficient. Obviously, depending on the method of integration, other design features of the radiator will already be provided for in the target equipment. In particular, the device of the bithermic heat exchanger of a gas boiler is oriented towards heating with a burner, therefore the casing may provide additional layers of protection. It is mandatory for all heat exchangers to provide security measures against the circuit of an electric current. Since the circuits can interface with other utility lines, grounding and the presence of fuses in the boiler stations is also mandatory.
How does a bithermic heat exchanger work?
Operating modes for heating and hotwater supply have several differences. In the first case, there is a standard heating of water in the process of gas combustion - if we are talking about the same gas boilers, for example. That is, in heating mode, direct heating of the coolant occurs, which then circulates around its circuit. As for the mode of operation in the format of hot water supply, this function is in some way secondary. Primary heating of the heat carrier also occurs, and already from it heat is transferred to sections with water intended for hot water supply. In this case, heat exchangers for heating do not spread water for heating along the respective circuits - it remains in its section. Almost for all bithermic boilers, one rule applies - at the same time only one of the two circuits can work. Simultaneous circulation of water for heating and DHW is not allowed.
Boilers on bithermic heat exchangers
Использование битермических радиаторов в boiler plants is becoming more common. Often, large manufacturers themselves develop models of projects on their own components, among which are heat exchangers. One of the leaders in the segment is Immergas, which offers boilers with 6 tube heat exchangers. This design gives a plus compared to 4 and 5-tube heat exchangers, since the expanded section can be located close to the flame of the burner. However, it is necessary to take into account the thermal power, which will provide the 6-tubular heat exchanger of the boiler. Bitermic principle of operation in this case is capable of producing about 24 kW and this may be redundant for private houses and large country cottages. Also, the development of bithermic units involved in the company Vaillant, Navien, Protherm. The products of these manufacturers are distinguished not only by modern design, but also by functionality. Engineers seek to provide models with the ability to smoothly adjust the flame, the option of cooling the heat exchanger, etc.
The advantages of bithermic aggregates
Достоинства теплообменников с единым блоком extend to the efficiency of heating as such, and the convenience of control, not to mention the higher reliability of the units. As for efficiency, bithermic radiators function with a lower coefficient of heat loss. If in a system divided into two blocks, heating of two blocks is required, then in this case the filling of one case 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 performance of a single unit, which affects the accuracy of the data obtained. Reliability, in turn, is achieved by minimizing the connecting infrastructure - in essence, only a bundle between the heat exchanger and the supply channels is required.
Disadvantages of construction
The main disadvantage of bithermic constructionis a limitation when working with liquids saturated with salt. In this context, we can note the imperfection of the monoblock case and coaxial circuits inside, which quickly become covered with scale. In addition, the bithermic heat exchanger is not able to provide the same performance as in the case of separated radiators. This applies specifically to hot water supply, since the construction itself implies a smaller amount of water serviced for such tasks.
Customer Reviews
The users themselves mostly emphasizeenergy efficiency of this solution. Owners of boilers and boilers, who have previously dealt with traditional split heat exchangers, indicate both high heat transfer and low gas consumption. But this refers to the cases when it is the gas supply infrastructure used in which boilers with a bithermic heat exchanger are introduced. Reviews of the owners, who rarely use the heating function - on the contrary, speak about the disadvantage of such units. The fact is that boilers with divided heating make it possible to work purposefully for one of the tasks - heating or DHW, which turns out to be more economical.
Nuances of operation
Bithermic equipment manufacturersnote that it is possible to prevent rapid wear of the heating filling by complying with several operating rules. These include, in particular, ignoring prophylactic contour testing. Most often, a bithermic heat exchanger for the heating and hot water systems is established with the expectation of long-term and regular operation. In intensive mode, even relatively clean water can adversely affect the condition of the radiator pipes. Accordingly, cleaning of the section surfaces is periodically required.
Not recommended and sharply increase the temperatureheating. In contrast to split heat exchangers, monoblock systems take longer to prepare DHW. When heat exchangers are used for heating, it is almost imperceptible, because for such tasks water warms quickly. But the liquid for domestic needs, as already noted, heats up secondarily.
Conclusion
The choice in favor of bithermic boiler shoulddo only after a clear analysis of the needs for water and heating. Such an option justifies itself in situations where it is planned to use both heating and hot water in approximately the same amount. Of course, in summer, the bithermic heat exchanger will noticeably lose in energy efficiency to classical radiators, but over the period of a long winter this difference is leveled in favor of the first option. In addition to the advantages of the combined heating units can be attributed to the compact design. Usually these are small boilers that do not take up much space and easily mate with control thermostats.
