Heat exchanger for heating for hot water

Heat exchanger for heating is the most important component of any boiler. From its performance depends on the "life" of the heating unit. Let's look at which heat exchanger for the heating system will allow to ensure efficient operation of the boiler and prolong its service life.

What are aggregates of this category?

Plate heat exchanger for heating is a technically complex system by means of which energy is transferred between the hot and cold coolant. In practice, liquids and vapors are used for this, less often gases and 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 aggregates of this category by definition. However, a bed or a shield, which reflects the heat of the flue gases from the stove, can be considered as an example of a heat exchanger, since they heat the air in the room.

The efficiency of energy transfer here depends on the following:

• Temperature differences between media (the presence of a significant difference causes a more impressive transfer of energy).
• Areas of contact of individual media with a heat exchanger.
• Indicators of thermal conductivity of construction materials .

In fact, the heat exchanger for hot water from heating can be represented by any pipe that is used to transmit a particular working medium, which has a temperature different from that of the surrounding space.

Types

One of the determining criteria for 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 assumed to be in the form of a working medium, preference should be given to plate-type soldered-type structures. The same applies to the use of coolants, which do not leave behind any deposits on the walls of the structure, for example alcohol, freon or ethylene glycol.

When talking about large-scale thermal points, such as boiler rooms, it is often possible to see a heat exchanger for hot water from heating of the demountable type. The use of such solutions can be explained by the presence of a poor quality working medium, which is used in centralized heating networks.

The simplicity of the construction of the dismountable plate aggregates facilitates their convenient maintenance, in particular, rapid disassembly, if it is necessary to remove scale from internal channels. At the same time, replacement of the parts of such a heat exchanger, be it flanges or latches, is even possible for inexperienced masters.

According to the method of energy transfer, it is necessary to distinguish a mixing and surface heat exchanger for heating. The first functions according to the principle of energy propagation during direct contact between individual heat carriers. The second type transfers energy through the plates without direct contact of the working media.

If it is necessary to use a heat exchanger for heating as an element for heating water in the pool or as a cooler in industrial plants, lamellar and brazed units are recommended for this purpose. Such designs allow one to quickly achieve the most effective heat exchange between two liquids.

Materials

The heat exchanger for house heating can be made of steel or cast iron plates, connected by soldering with copper or nickel solder. The structures brazed with copper are common in centralized heating systems. At the same time, systems, the elements of which are connected with the use of nickel, are used mainly to meet the needs of industrial spheres and, if necessary, work with chemically aggressive media.

Cast iron

Preferring cast iron heat exchangers should pay attention to several points:

1. It's quite an impressive weight, which must be taken into account when developing a project for the arrangement of the boiler house. With regard to the introduction of such structures in the heating system of a private house, the latter should be characterized by a low volume of sections, a minimum number of smoke channels that are used to move combustion products.
2. Cast iron units are characterized by the possibility of sectional transportation in disassembled form, which becomes convenient for installation and subsequent maintenance.
3. Despite the weight, the material is rather fragile. Therefore, during transport and installation it is necessary to avoid mechanical influences on the elements of the structure. Another danger is thermal shock. With a sharp location in an unheated unit of an impressive volume of cold working medium, the walls of the heat exchanger may crack.
4. Cast iron lends itself 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 film of rust as it is used. Since heat exchangers for heating a private house made of cast iron have thick walls, these processes can last for many years.
5. Such systems for a long time heat up, but extremely slowly cool down, which significantly reduces fuel consumption and increases the efficiency of heating the premises.

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 of this material, is often used to serve large areas.

As for the convenience of mounting the steel structure, the final assembly, unlike the cast-iron units, takes place in the factory. One-piece candy bar is quite difficult to bring into a close room. In addition, factory assembly complicates the repair and maintenance of the system.

Installed steel heat exchanger in the heating furnace, which received serious damage, is almost impossible to return back to life at home. It is necessary either to resort to complete dismantling of the system and sending it for repair to the industrial workshop, or to get rid of the construction, performing its replacement.

At the same time, the water heat exchanger for heating from steel is not afraid of thermal shock, nor of significant mechanical loads. The material is characterized by a high index of elasticity and therefore perfectly copes with sharp temperature changes. However, with prolonged exposure to strong cold or heat, small cracks can form on the welds.

If we talk about the ability to withstand corrosion, the steel heat exchanger is subject only to electrochemical effects. Especially quickly with prolonged contact with corrosive rust environments, thin walls are eroded. At the same time, the service life of the system can be systematically reduced for a period of 5 to 15 years. Proceeding from this, manufacturers often cover the internal walls of steel heat exchangers with cast iron.

Systems from this material almost immediately warm up and just as quickly cool down. Despite the obvious convenience in the need for rapid heating of premises, this property has a reverse, negative side. So, the effect of metal fatigue in certain parts of the structure can lead to the appearance of minor damages.

How to make a heat exchanger calculation?

Performing self-assessment is one of the most common questions from consumers. In fact, it's extremely difficult to cope with the task, as heat exchanger manufacturers try to hide the secrets of their own developments from outsiders, including users.

For the above reason, it becomes difficult to ascertain the actual energy consumption during heat transfer. If this indicator is known to be low, respectively, the efficiency of the heat exchanger will not be sufficient to meet the existing needs.

To increase system performance, it is often necessary to install volumetric 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 by own hands

How to make an effective design with its own hands, which will cope with the functions of heat exchange? For this it is sufficient to return to the definition, which is typical for devices of this category. It turns out that to build a simple heat exchanger, it is enough to take a metal pipe of a certain length, roll it into a ring and place it in a container filled with water.

By pulling out the outlet and the inlet of the pipe, it is possible to obtain a functional design that will either heat or cool the working fluid, depending on the existing need.

Heat exchanger "water jacket"

In addition to the system in the form of a coil, it is possible to make a heat exchanger, known as a "water jacket" by itself. Such systems operate on the basis of the principle of energy distribution between several sealed containers placed in each other.

Heat transfer according to this principle is successfully used in small-size solid fuel boilers. Despite the overall simplicity of the design, the lack of such systems is the presence of a relatively low operating pressure, which these units are designed for. In addition, the manufacture of heat exchangers, functioning on the principle of "water jacket", should engage an experienced welder. To construct and assemble such a system from improvised materials, without having the appropriate skills, is rather problematic.

Pipe plate heat exchanger

Probably the most difficult of all options available for independent production is a system called the "pipe board". This definition was assigned to self-made heat exchangers, which contain a substantial number of rolling joints.

Such aggregates are represented in the form of three sealed containers. Two of them are placed on the opposite edges of the structure and are connected by metal conductors of the working medium, which expand at the ends of such vessels. Heat transfer is performed in the third - middle - part due to the movement of the liquid working medium between the containers through the pipes.

In the search for alternative solutions

If there is no possibility for self-assembly of the heat exchanger by the above methods, you can try to find materials for the production of a future system in your own storage room or in a landfill. For example, an excellent solution for creating a device in the form of a coil will be an old heated towel rail. Any household radiator that does not have leaks is also suitable.

With regard to the use of radiators from car stoves, in fact, they can immediately be used as a heating element, combining individual units with adapters to increase the area of exchange of thermal energy.

An effective device can be created on the basis of an old water-heating column. In this case, you do not even have to do anything about it.

Eventually

As you can see, the principle of operation of heat exchangers is approximately the same everywhere. Depending on the operating conditions, such units can operate both for heating and cooling the working fluid: gas, liquid or solid.

When choosing a factory solution, much depends on the tasks that are assigned to the heat exchanger, and in case of self-assembly - from the engineering fantasy of the master.