Technological progress in the segment of heating equipment is developing in different directions. Some manufacturers are betting on improving the performance of the element base of the units, others are promoting the latest automatic control devices, and still others are also engaged in design optimization at the basic level. 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 domestic hot water, that is, for domestic consumption.
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. At the same time, it would be wrong to assume that in the second case, water is mixed - such a principle does not allowbithermic heat exchanger. 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. Whereas a standard split heat exchanger initially contains two different chambers.
Structural device
Now it is 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 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 security measures againstshort circuit of electric current. Since the circuits may interface with other utility lines, grounding and fuses in boiler stations are also mandatory.
How does a bithermic heat exchanger work?
The 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 somewhat secondary. The primary heating of the coolant also takes place, and already from it heat is transferred to sections with water intended for hot water supply. In this case, the heat exchangers for heating do not distribute heating water 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.
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 heat exchangers for 6tubes. 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, which will be provided by the 6-tube heat exchanger of the boiler. 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 smooth flame adjustment options, heat exchanger cooling options, etc.
Advantages of bithermic aggregates
The advantages of single block heat exchangers extend 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 in a system divided into two blocks heating of two blocks is required, 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, it requiresjust a link between the heat exchanger and the supply channels.
Design flaws
The main disadvantage of the bithermic design is the limitation when working with liquids saturated with s alts. 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 assumes a smaller amount of water serviced for such tasks.
Consumer Reviews
Users themselves mainly emphasize the energy efficiency of this solution. Boiler and boiler owners who have previously de alt with traditional split heat exchangers point to both high heat transfer and low gas consumption. But this applies to cases when it is the gas supply infrastructure that is used, into which boilers with a bithermic heat exchanger are introduced. Reviews of owners who rarely use the heating function, on the contrary, speak of the unprofitability of such units. The fact is that boilers with split heating allow you to work purposefully for one of the tasks - heating or hot water, which turns out to be more economical.
Exploitation nuances
Manufacturers of bithermic equipment note that it is possible to prevent rapid wear of the heating fillingby following a few operating rules. These include, in particular, ignoring the preventive check of the circuits. Most often, a bithermic heat exchanger is installed on a heating system and hot water with the expectation of long-term and regular operation. In intensive operation, even relatively clean water can adversely affect the condition of the radiator pipes. Accordingly, periodically cleaning of the surfaces of the sections is required.
It is not recommended to sharply increase the heating temperature. Unlike split heat exchangers, monobloc systems require more time to prepare domestic hot water. When heat exchangers are used for heating, this is almost imperceptible, because for such tasks the water is heated quickly. But the household liquid, as already noted, heats up in the second place.
Conclusion
The choice in favor of a bithermic boiler should be made only after a clear analysis of the needs for water and heating. This option justifies itself in situations where it is planned to use both heating and hot water in approximately the same volume. Of course, in the summer, a bithermic heat exchanger will noticeably lose in energy efficiency to classic radiators, but during a long winter this difference is leveled in favor of the first option. In addition, the compactness of the design can be attributed to the advantages of the combined heating units. Usually these are small boilers that do not take up much space and are easily interfaced with control thermostats.
