What heat exchanger is best for a 20 kW heating boiler? If you want to increase the thermal efficiency of your boiler, it's worth considering the use of a plate heat exchanger. Plate heat exchangers are often chosen as an effective solution for heat transfer in high-power heating installations. They operate on the principle of fluid flow through specially shaped channels, allowing for quick and effective heat transfer. As a result, plate heat exchangers can provide efficient room heating and deliver hot water. They are also easy to clean and maintain. Before choosing a specific model of plate heat exchanger, we recommend reading the blog post below, which will make it easier to select the right heat exchanger for your 20 kW boiler.
✅ A plate heat exchanger is a device used for efficient heat exchange between two streams of fluids (or gases). It consists of a set of plates arranged to create channels through which the thermal fluid flows. The plate heat exchanger allows for the transfer of heat from one stream to another through direct contact between the plates. The temperature difference between the streams allows for heat flow from the higher temperature area to the lower temperature area. Due to its design, the plate heat exchanger is easy to clean and has a compact structure. It is widely used in various industries, such as the chemical, food, and energy industries, due to its high efficiency and energy savings.
A plate heat exchanger consists of metal thermal plates, which depending on the application, can be made of various materials, such as:
Each plate responsible for heat exchange has a grooved surface, which increases the contact area and improves the efficiency of the exchange. The exchanger also consists of an end plate, which is responsible for supplying the heating medium to the thermal plates inside it, and a closing plate, which protects the exchanger from fluid leakage. Due to its construction and the use of various materials, the plate heat exchanger is a versatile device, ideal for use in many industries, including the chemical, food, and heating industries.
Plate heat exchangers differ in the way the plates are connected. We distinguish the following types of plate heat exchangers:
✅ A plate heat exchanger has wide applications in various fields. It is used, among other things, to connect boilers to closed systems in central heating installations. It can also be used to connect underfloor heating, ensuring even and efficient distribution of heat in rooms. Additionally, a plate heat exchanger can be utilized in conjunction with heat pumps, serving as a condenser or evaporator. This allows for the efficient utilization of renewable energy and cost savings.
Finally a plate heat exchanger is also used in refrigeration in the food industry, where it is necessary to maintain the proper temperature in the production and storage of food products. Due to its functions and versatile applications, the plate heat exchanger is an indispensable element of modern heating and cooling installations.
In order to select the appropriate plate heat exchanger for a central heating system, the key parameters of its operation should be taken into account, as described below.
The heat exchanger works with various types of media, such as water, air, or glycol. Depending on the requirements, it can be used to transfer heat from one medium to another or to cool a given medium. Due to the medium, the following types of plate heat exchangers can be distinguished:
The medium can make a difference, because specific media (like gases) can require special pressure resistance. ❌ If the given heat exchanger was not certified for high pressures - like 4 - 4.5 MPa - it shouldn't be used with F-gases and refrigerants.
✅The power of the plate heat exchanger depends on the power of the central heating boiler. Various models with different capacities are available on the market. For example, plate heat exchangers adapted to heating boilers with a maximum power ranging from 15 kW to 100 kW (or even higher power) can be found, enabling effective heat exchange between two media, such as the heating fluid and the medium to be heated.
When selecting the nominal power of the exchanger, it should not be directly compared to the nominal power of the boiler. For example, for a 20 kW furnace, the appropriate heat exchanger should have a nominal power in the range of 30-55 kW (depending on the supply temperature).
In most cases, the maximum operating temperature of the plate heat exchanger used in households is 230°C. This is the temperature at which the exchanger can effectively transfer heat between two substances. Exceeding this temperature can cause damage to the exchanger plates and reduce its efficiency - but in practice, this is not possible outside of industrial applications.
✅ The maximum operating pressure of the plate heat exchanger is the highest pressure that can be maintained inside the exchanger during normal operation. When connecting a 20 kW furnace to a plate heat exchanger, the exchanger's operating pressure should be in the range of 20-30 bar. Exceeding this value can lead to damage or failure of the exchanger, so it is necessary to monitor and maintain it within the appropriate parameters. Fortunately, liquid-liquid installations, powered by heat sources such as: heating boilers, fireplaces, heat pumps - do not exceed a few bars (rarely more than 2-3 bars). Therefore, 20-30 bar is definitely a limit ensuring long-term use of plate heat exchangers. In domestic applications, aiming for higher pressure (there are exchangers on the market up to 45 bar) - has no technical justification.
Plate heat exchangers for central heating boilers are most commonly made of high-quality stainless steel 316L, which is characterized by excellent corrosion resistance. Between the plates of the heat exchanger, copper solders are used, ensuring good thermal conductivity. Thanks to this, the plate heat exchanger effectively transfers thermal energy between two media, allowing for efficient cooling or heating.
✅ For a 20 kW boiler used in households for heating, classic heat exchangers made of stainless steel 316L are recommended.
The number of plates in a heat exchanger significantly affects its efficiency. With an increase in the number of plates, the surface area of the exchanger increases, which translates into greater heat transfer efficiency. Therefore, it is important to select the appropriate number of plates to achieve optimal heat exchanger performance. However, it should be remembered that ultimately, the total plate surface area - or in other words, the heat exchange surface area - is more important than the number of plates. It is possible to find a highly efficient heat exchanger with a small number of plates (e.g., a 20-plate exchanger), provided that it is a extensive plate providing a large unit area.
✅ For a 20 kW boiler, whose task is to heat a house or heat water, the optimal number of plates in the exchanger is in the range of 20-50, depending on the final heat exchange surface area, which must oscillate within 0.50-0.70 square meters. Such a number of plates and surface area allows for efficient heat transfer while maintaining a compact exchanger size, which is crucial during installation in limited home spaces.
✅ In response to the question from the above blog post, for a 20 kW boiler described in the article, meeting all the conditions mentioned above, the following plate heat exchangers would be the best choice:
Thanks to their design, the above heat exchangers enable quick and efficient heating of rooms of various sizes. Their main advantage is their compact construction, making it possible to install them even in small spaces. These plate heat exchangers can be successfully used in single-family houses as well as in commercial buildings, providing high heating efficiency. Therefore, if you are looking for an efficient and economical solution for your 20 kW boiler, it is worth considering the use of our plate heat exchangers.
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