The heat exchanger for heating is the most important component of any boiler. The "life" of the heating unit depends on its performance. Let's look at which heat exchanger for the heating system will ensure the efficient functioning of the boiler and extend its service life.
What are the aggregates of this category?
A plate heat exchanger for heating is a technically complex system that transfers energy between hot and cold coolant. In practice, liquids and vapors are used for this, less often gases, solid bases.
In other words, a heat exchanger for heating is a device that does not have its own heat source, and its functionality is provided by energy that comes from a centralized heating system. That is, a boiler or stove does not belong to the units of this category by definition. However, a bench or a shield that reflects the heat of flue gases from the stove can be considered examples of a heat exchanger, since they heat the air in the room.
The power transfer efficiency here depends on the following:
- Temperature differences between environments (the presence of a significant difference causes more impressive energy transfer).
- The area of contact of individual media with a heat exchanger.
- Indicators of thermal conductivity of construction materials.
In fact, a heat exchanger for hot water from heating can be represented by any pipe that is used to transfer a particular working medium, which has a temperature different from that of the surrounding space.
Types
One of the determining criteria when choosing a heat exchanger of a certain plan is not only the nature of the coolant, but also its quality. If the use of softened or chemically purified water is supposed to be used as a working medium, it is better to give preference to brazed plate structures. The same applies to the use of coolants that do not leave behind any deposits on the walls of the structure, such as alcohol, freon or ethylene glycol.
When it comes to large-scale heating points, such as boiler houses, here you can most often see a heat exchanger for hot water from a collapsible type of heating. The use of such solutions can be explained by the presence of a low-quality working environment, which is used in centralized heating networks.
The simplicity of the design of collapsible lamellar units contributes to their convenient maintenance, in particular, quick disassembly duringthe need to remove scale from the internal channels. At the same time, even inexperienced craftsmen can replace the parts of such a heat exchanger, whether it be flanges or valves.
According to the method of energy transfer, it is worth highlighting the mixing and surface heat exchanger for heating. The first operates according to the principle of energy distribution in direct contact between individual heat carriers. The second type transfers energy through the plates without direct contact between the working media.
If it is necessary to use a heat exchanger for heating as an element for heating water in a pool or as a cooler in industrial installations, it is recommended to use plate and brazed units for this purpose. Such designs allow the most efficient heat transfer between two fluids to be achieved quickly.
Materials
A heat exchanger for heating a house can be made of steel or cast iron plates, connected by soldering with copper or nickel solder. Copper brazed structures are common in centralized heating systems. At the same time, systems, the elements of which are connected using nickel, are mainly used to meet the needs of industrial areas and, if necessary, work with chemically aggressive environments.
Cast iron
Giving preference to cast-iron heat exchangers, you should pay attention to a few points:
- Sufficiently impressive weight thatmust be taken into account when developing a project for the arrangement of a boiler room. As for the introduction of such structures into the heating system of a private house, the latter should be distinguished by a small volume of sections, a minimum number of smoke channels that are used to move combustion products.
- Cast-iron units are distinguished by the possibility of sectional transportation in disassembled form, which becomes convenient for installation and subsequent maintenance.
- Despite the weight, the material is quite fragile. Therefore, during transportation and installation, mechanical impacts on structural elements should be avoided. Another danger is thermal shock. If an impressive volume of cold working medium is placed abruptly into the unit that has not cooled down, the walls of the heat exchanger may crack.
- Cast iron is susceptible to both wet and dry corrosion. The first is formed as a result of exposure to the material of acid condensate. The second slowly covers the surface of the structure in the form of a rust film as it is used. Since heat exchangers for heating a private house made of cast iron have thick walls, these processes can take many years.
- Such systems heat up for a long time, but cool down extremely slowly, which significantly reduces fuel consumption and increases the efficiency of space heating.
Steel
The presence of a steel "heart" does not lead to a significant weighting of the system. Therefore, a water heat exchanger for heating made from this material is oftenused to service large areas.
As for the ease of installation of the steel structure, the final assembly, unlike cast iron units, takes place in the factory. One-piece monoblock is quite difficult to bring into a cramped room. In addition, the factory assembly somewhat complicates the repair and maintenance of the system.
The installed steel heat exchanger in the heating furnace, which has received serious damage, is almost impossible to bring back to life at home. You either have to resort to the complete dismantling of the system and send it to the industrial workshop for repair, or get rid of the structure by replacing it.
At the same time, a water heat exchanger for heating made of steel is not afraid of either thermal shock or significant mechanical stress. The material has a high rate of elasticity and therefore copes well with sudden temperature changes. However, prolonged exposure to extreme cold or heat can cause small cracks in the welds.
If we talk about the ability to resist corrosion, the steel heat exchanger is subject only to electrochemical influences. Especially quickly, with prolonged contact with aggressive media, thin walls are corroded by rust. At the same time, the service life of the system can be systematically reduced by 5 to 15 years. Based on this, manufacturers often cover the inner walls of steel heat exchangers with cast iron.
Systems made of this material heat up almost instantly and cool down just as quickly. Despite the obvious convenience, if necessaryrapid space heating, this property has a downside, a negative side. Thus, the effect of metal fatigue in certain sections of the structure can lead to minor damage.
How to calculate the heat exchanger?
Do-it-yourself calculations are one of the most common questions from consumers. In fact, it is extremely difficult to cope with the task, as heat exchanger manufacturers try to hide the secrets of their own developments from outsiders, including users.
Because of the above reason, it becomes difficult to find out the real energy consumption of heat transfer. If this indicator is deliberately low, accordingly, the efficiency of the heat exchanger will be insufficient to meet existing needs.
To increase the performance of the system, it is often necessary to install bulky units. However, in order to reduce the number of heat exchanger plates used, it is enough to use a special calculation program that every serious manufacturer of heating equipment has.
Heat exchangers for heating with your own hands
How to make an efficient design that will cope with heat transfer functions with your own hands? To do this, it is enough to return to the definition that is typical for devices in this category. It turns out that to assemble a simple heat exchanger, it is enough to take a metal pipea certain length, roll it into a ring and place it in a container filled with water.
By bringing the outlet and inlet of the pipe outside, it is possible to obtain a functional design that will either heat or cool the working fluid, depending on the existing need.
Water jacket heat exchanger
In addition to the serpentine system, you can make your own heat exchanger, known as the "water jacket". Such systems operate on the basis of the principle of energy distribution between several sealed containers placed in each other.
Heat exchange according to this principle has been successfully used in small-sized solid fuel boilers. Despite the general simplicity of design, the disadvantage of such systems is the presence of a relatively low operating pressure, for which these units are designed. In addition, the manufacture of heat exchangers operating on the principle of "water jacket" should be carried out by an experienced welder. It is rather problematic to design and assemble such a system from improvised materials without having the appropriate skills.
Tube board heat exchanger
Probably the most difficult of all the options available for self-manufacturing is a system called "tube board". This definition has been assigned to homemade heat exchangers that contain a substantial amount of expanding pipe connections.
Such units are presented in the form of three sealed containers. Two of them are placed on opposite edges of the structure and connectedmetal conductors of the working medium, which are flared at the ends of such vessels. Heat exchange is carried out in the third - middle - part due to the movement of the liquid working medium between the tanks through the pipes.
Searching for alternative solutions
If there is no way to self-assemble the heat exchanger using the above methods, you can try to find materials for the manufacture of the future system in your own closet or in a landfill. For example, an old heated towel rail would be an excellent solution for creating a device in the form of a coil. Any household radiator that does not leak will also work.
As for the use of radiators from car stoves, in fact, they can be immediately used as a heating element by combining individual units with adapters to increase the heat exchange area.
An effective device can be created on the basis of an old water heater. In this case, you don’t even have to redo almost anything.
In the end
As you can see, the principle of operation of heat exchangers is approximately the same everywhere. Depending on the operating conditions, such units can work both for heating and for cooling the working medium: gas, liquid or solid.
When choosing a factory solution, a lot depends on the tasks assigned to the heat exchanger, and in the case of self-assembly, on the engineering imagination of the master.
