What types of heat exchangers are there for hot water powered by a heating system?

Heat exchanger is equipment in the working unit of which heat exchange between elements with different temperatures is established.

What do heat exchangers look like?

Advantages of heating systems based on heat exchangers:

• ease of operation and ease of maintenance;
• durability;
• uniform heating of large areas;
• convenient thermal control system;
• no bulky radiators;
• thermal comfort in the room.

Areas of application

Design, diagram and principle of operation of flow-through gas columns

The following areas of use of heat exchange equipment are distinguished:

• cooling systems;
• heating systems;
• air conditioning systems;
• chemical industry;
• heating of swimming pools;
• solar collectors;
• mechanical engineering;
• ventilation systems;
• metallurgy;
• pharmacy;
• auto production;
• food industry.

In addition, it is possible to use heat exchange equipment for heating private households. You can install the device either independently or with the help of a wizard. Using this technique helps to evenly distribute heat in the room.

Washing methods

There are simple variations that practically do not involve any expenses, there are budget ones with minimal investments, and professional ones - they cost much more, but are highly effective.

How to flush the secondary heat exchanger of a gas boiler in one way or another? And when is it logical to use them. It all depends on the volume of deposits.

In the simplest situation, mechanical cleaning is sufficient. The outside of the VT ribs are cleaned. The work uses any hard brush, spatula, scraper or cable. It is very important here not to damage the plates.

The second method is washing with a special composition. In practice, it is combined with the first method and follows immediately after it.

The part is placed in a container with an acid mixture. Type of acid used: hydrochloric or citric. Suitable proportions: 100 grams per 10 liters. Water.

Acids can be replaced with any anti-scale preparations. After 30-40 minutes, the VT is removed from the container. The remaining scale is carefully wiped off.

At the same time, the coil is also cleaned. A special steel brush is used here.

The third method is chemical. More aggressive substances are pumped through the VT using a special pump. It attaches to the pipes of the part.

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Suitable tools for the job are shown in this table:

Facilities	Description	Proportion to water: grams: liter	Water temperature	Product price (RUB)
Lemon acid	Popular folk remedy	100 : 10-12	50-70°C	50 – 1 sachet.
Thermagent Active	A versatile liquid with a powerful effect	1 : 9	40-50°C	1500 – 10 kg canister.
STEELTEX Cooper	One of the most effective preparations, but suitable for working with light alloy parts	1:6 to 1:10	40-60°C	1300 – 5 kg capacity
Detex	Concentrate with effective biological substances. Excellent cleaning of steel, cast iron and copper parts	200-500 :10	40-50°C	4900 – 10 l canister.
Hydrochloric acid	Effectively removes heavy scale	100 : 10	50-70°C	50 – 1 kg

A hose is placed in the container with the mixture almost to the very bottom, one side connected to the VT, and the other to the pump. This creates the necessary circulation. The procedure lasts 30-40 minutes. Then the part is thoroughly washed with plain water.

The fourth method does not involve extracting the component. This is a hydrodynamic flushing of the secondary heat exchanger of a gas boiler. But it is carried out only by professionals. This requires special technology and compliance with safety criteria.

Its principle is to run a special composition through the boiler system under powerful pressure (1.5-2 bar). The work is done by a booster. Abrasive elements are added to the cleaning liquid.

This is the most effective method, gently removing all deposits and cleaning the part to a commercial appearance.

If you doubt the success of self-cleaning, you can order this service. All operations are carried out within a day. Their price tag is determined by the following factors:

• region,
• power and boiler modification,
• company's markup,
• the equipment and chemicals used.

In Moscow and the central region, clients pay about 3,500-9,000 for services. In St. Petersburg - 3,000 - 7,000 rubles. In other regions: 1700 – 4500 rubles.

Classification

The classification of heat exchangers involves dividing them into the following types:

• lamellar;
• tubular.

Thermostat for a heating radiator: types and principle of operation

Plate devices include a series of plates with wavy channels with stampings and surfaces designed to circulate fluids. The plates are connected using rubberized gaskets and ties. The advantages of such devices are ease of use and compactness.

Plate heat exchangers are increasingly used. The scope of their use is not limited only to industrial equipment; it is also possible to install these devices in residential buildings for the installation of heating systems.

Plate heat exchangers are classified into groups:

• non-separable (also welded and soldered);
• semi-welded;
• collapsible.

Collapsible devices are the most popular. In them, the plates are separated using rubber seals. Installation does not take much time, and operation is easy.

The classic version of plate heat exchangers has inlet and outlet pipes on the surface of the front plate. Some devices have connections on both the front and rear panels. Working media are connected to the pipes using flanged, threaded, steel connections. Some models have a smaller number of pipes, then the coolants are connected directly to the stove.

Tubular heat exchangers involve small diameter tubes welded into other tubes. The advantages of the device are considered to be used in conditions of increased pressure.

According to the criterion of the heat exchange method, equipment is divided into mixing and surface. Mixing-type devices transfer heat when the media are in close contact. Surface heat exchangers contain two circuits in which media with different temperatures move. Heat exchange between them is possible through the surface elements of plates, walls, sheets or pipes, which are made of heat-conducting materials (stainless or high-carbon steel, non-ferrous metal alloys). This type of equipment is used in housing and communal services, industrial enterprises and small businesses.

Surface heat exchangers are divided into types: recuperative and regenerative. Recuperative heat exchangers are characterized by constant heat exchange through the walls of the circuits with unidirectional movement of the carriers. In regenerative devices, alternate contact of carriers with a heat-exchange surface occurs.

Recuperative heat exchangers are also classified:

1. Submersible. The principle of operation involves the movement of one coolant along a coil, which is immersed in a tank containing a second coolant liquid. The model is easy to use and has an optimal price.
2. Irrigation. Field of application: as capacitors in cooling systems. Heat exchangers look like coils made of horizontal pipes that are placed in a vertical plane. Each row of pipes has a gutter through which water at a low temperature flows onto them. Water that has not evaporated is returned to the system thanks to the pump.
3. Twisted. They are a system of pipes wound around a core. Compact and highly efficient.
4. Spiral. The equipment is characterized by the appearance of two spiral channels, which are wrapped around the central partition. Designed for cooling and heating viscous liquids.
5. Shell and tube. The tube sheets are attached to the casing by welding. Pipes are fixed in them. They are fastened tightly using flaring. The grilles are closed with covers on studs, bolts and gaskets. The casing includes fittings (pipes). The principle of operation is the circulation of a coolant in the interpipe space and through the pipes. Increased heat transfer occurs with the help of fins.
6. Sectional – a sequence of sections that represent shell-and-tube devices.
7. Lamellar. Includes a set of plates with wavy surfaces with stamping and channels for the movement of liquids. Operation is only possible at reduced pressure.

Shell and tube heat exchanger

Material of manufacture

The heat exchanger for the boiler is made from durable materials that conduct heat well, are not prone to corrosion and are sufficiently resistant to pressure. Since the cost of the material also has to be taken into account, the choice is limited.

Steel

A steel heat exchanger is cheaper in price, but less durable.
This is the most affordable material. Steel is very strong, but can be processed well. The price is low. The advantage of this option is resistance to high temperatures. Steel is plastic and does not crack when heated, and does not deform even in areas in contact with the burner.

A steel heat exchanger for a solid fuel or gas boiler is prone to corrosion. Water inside the tubes and combustion products in the boiler chamber have a destructive effect on the material. This affects durability. The steel model weighs a lot, which leads to additional fuel consumption for heating the element itself.

The stainless steel heat exchanger is resistant to corrosion and lasts for at least 50 years.

Cast iron

The material is much more resistant to corrosion than steel, and is not afraid of rust and the action of acid anhydrides. The service life reaches 50 years. However, cast iron is a brittle alloy and can crack under the influence of temperature. To avoid damage, the cast iron tubular heat exchanger must be washed: if ordinary water is used, then once a year; if antifreeze - then once every 2 years; if distilled liquid - once every 4 years.

The weight of a cast iron element is even greater, so more fuel and time have to be spent on heating.

Copper

Copper is a noble metal that is not susceptible to any type of corrosion. It is chemically inert and tolerates pressure well. Copper conducts heat better, so less fuel is required to heat the element itself and the flowing liquid. The weight of the copper model is small, the dimensions are compact with a very developed working surface.

The disadvantage is the high price. Also, the copper heat exchanger is too sensitive to heating to high temperatures. More often found in boilers from foreign manufacturers.

Structure and principle of operation

The mechanism of action is easy to consider using the example of a factory-assembled plate heat exchanger. The structure provides two circuits and four outputs. The plate device separates the flows by pressure and temperature. Coolants are acids and other liquids.

Mayevsky crane: principle of operation

Heat exchangers for heating involve connection to one circuit of underfloor heating, and to the other - a heating plant.

Direct connection of the central coolant is impossible, since this leads to failure of the warm floor covering.

This occurs due to increased pressure in the heating plant, temperature changes and the presence of chemically aggressive substances in the coolant.

The structure of the heat exchanger is shown in the figure below.

Schematic design of a plate heat exchanger

The structure of the heat exchanger is:

• a frame, which on one side of the device is attached to a stationary pressure plate and serves as a support element;
• a package of plates that forms channels for coolant between the constituent elements;
• frame, which consists of a movable pressure plate, a fixed pressure plate and a rear pillar;
• a casing that serves to protect the device from external influences;
• studs that are placed along the edge of the holes through which coolant enters the device;
• gasket required to seal the channels;
• supporting and fastening elements (guide beams, supporting base, legs of the bed and frame, bearings, bolts, nuts, washers).

The blue and red arrows in the figure indicate the directions of movement of the cold and hot coolant inside the heat exchanger, respectively.

In everyday life, a heat exchanger is used, whose operating principle is based on the separation of flows and maintaining the autonomous functioning of heated floors at a reduced operating pressure of 1.5 bar and the connection of clean water.

The structure of heat exchange equipment consists of three groups of plates:

1. Dialed belonging to an autonomous heating system with a reduced pressure level.
2. Dialed belonging to a central heating system with increased levels of temperature and pressure.
3. Separating, characterized by small thickness and transferring heat from a centralized system to an autonomous one.

The number and parameters of the plates determine the power of the heat exchange equipment. Each device requires the installation of a cleaning filter. It is able to retain coarse particles: scale, chips and others. The filter needs to be periodically washed with cleaning solutions.

Operating principle of the heat exchanger

The operating principle of the heat exchanger is to transfer thermal energy from one coolant to another. The device receives a direct heating medium and a cold medium. When they pass between the plates through the channels, the cold medium is heated. At the outlet of the heat exchanger, a heated medium and a return heating medium are obtained. Inside the equipment, heat transfer fluids move towards each other, that is, in countercurrent, and cannot mix because they are separated by plates.

Model types

The devices differ in the installation method. And this directly affects the efficiency of the entire system. Very often a boiler design is used that already has a heating heat exchanger inside. Heat losses in such devices are practically reduced to zero. And for productive work all you need is proper configuration.

External structures are much less efficient. Because their position does not allow the coolant to heat up well. But they are used where there are no individual heating boilers. For example, in houses using centralized heating.

Equipment characteristics

Heat exchange equipment is marked with the following data:

• test pressure level;
• maximum operating pressure level;
• maximum operating temperature level;
• manufacturer.

In addition, the package includes a diagram and a technical passport in the language of the manufacturing country, translated, if necessary, into the language of the selling country.

Diagonal and vertical arrangement of contours is possible. When the circuits are arranged diagonally, it is necessary to install only in a vertical position. Then it is possible for hot water to flow into the heat exchanger in the direction from top to bottom. In this case, heat is transferred to the autonomous system through separating plates.

The water at the inlet is at an increased temperature, and at the outlet it is reduced. In this case, in a circuit belonging to an autonomous system, the coolant moves from bottom to top. At the lower levels, the water is slightly heated, and when approaching the upper levels, the heating intensifies. This makes the system easier to operate. Water supply to the equipment is possible thanks to forced circulation.

Malfunctions, repairs

Gas heaters have light indication. It is intended to notify of malfunctions. Each manufacturer creates its own character code contained in the passport. If you don’t have a passport, you can download it on the Internet. Malfunctions can be divided into two categories:

• those that can be eliminated on your own;
• requiring specialist intervention.

What you can fix yourself is not specified in the passport. Common heat exchanger failures:

• depressurization;
• blockage

Elimination of leaks is carried out with a soldering iron, welding, depending on the metal. The second malfunction occurs due to poor-quality coolant, scale. Eliminated by washing. To remove scale, you can use phosphoric acid or citric acid. The first one is more effective. How to do it is shown in the video:

Sometimes there is a manufacturing defect, but more often the malfunction occurs due to improper use of the devices. If you strictly follow the manufacturer's recommendations, the product will last a long time and with high quality. Boiler repair:

Installation

Installation of a plate heat exchanger, as the most common, is carried out according to three options:

• parallel;
• mixed two-stage;
• sequential two-stage.

When installing in parallel, it is necessary to install a thermostat. This method saves space, time, and also does not require large expenses. The two-stage mixed circuit provides significant savings in coolant. This is achieved by using a reverse flow of warm water to heat the flow at a lower temperature.

Using a sequential circuit splits the incoming stream into two branches. One of them passes through the regulator, the other through the heater. Next, both flows are mixed and then enter the heating unit. This saves coolant. Full automation of the equipment is impossible.

Heat exchangers are fixed to the wall using a fastening tape, a console and a corner attached to the bottom of the device. After this, you need to install filters. The minimum condition is the presence of a filter system in the heating plant system. Before installation, it is worth preparing taps and American ones - threaded detachable connecting components. Each of them includes a union nut, a gasket and two fittings. It is important to select the correct spare parts so that they match the diameter of the connection system. Then installation will not be difficult.

Appearance of plate heat exchanger

Popular manufacturers

Aster heat exchangers of domestic production
In the Russian market, collapsible and soldered heat exchangers from the RIDAN and ASTERA brands have proven themselves well, characterized by a high level of quality and availability of the necessary spare parts.

Among foreign brands, buyers more often choose diesel and standard devices from ALFA LAVAL, DANFOSS and SONDEX.

When choosing a unit, you need to take into account the features of the system as a whole, the estimate, if we are talking about a project, requirements for the number of kW, as well as other necessary parameters.

Potbelly stove with heat exchanger. Video

You can learn about the features of making a potbelly stove from gas cylinders with a heat exchanger from the video below.

Despite the wide range of applications of heat exchangers, the most popular is their use as an additional heating system. Optimal technical characteristics ensure high-quality heating of rooms of any size. Installation of floors with heat exchangers does not take much time, they are easy to use and durable. It is necessary to conduct timely preventive inspections of the system in order to promptly eliminate possible problems.

Selection rules

Types of coolants used for heating systems
The list of main criteria that you need to pay attention to when choosing includes:

• type and quality of the thermal fluid used;
• ease of disassembly and assembly;
• type of heat transfer;
• the ability to increase the amount of power during operation.

Plate exchangers are more often used for cooling and heating systems of refrigerators and swimming pools, spiral exchangers are used in various industries, horizontal ones are better suited as heating devices.

Power calculations

It is almost impossible to independently calculate the power of a recuperator in the absence of initial data (furnace power, temperature and amount of exhaust gases per unit time, contact area between the heat exchanger and the metal of the chimney, the speed of passage of air or water through the device). You can measure the power of an already installed heat exchanger.

Roughly, you should expect that the heat exchanger on the chimney of a solid fuel stove or fireplace will warm up a couple of small radiators, increase the temperature in the garage, or make a room in the attic or a dressing room in a bathhouse warmer.

Air tank

You can improve an ordinary potbelly stove or sauna stove with a direct chimney by installing it on an air heat exchanger on the chimney .
It is a cylindrical body through which several hollow pipes pass. Air is sucked in from below, heated in the pipe, it leaves the heat exchanger, increasing the efficiency of the furnace by 15-20%. The air ducts can be routed to an adjacent room, thus heating several rooms or sections of the garage from one furnace. Video: how to make an air heat exchanger for a chimney

Another original design of a stove with an air heat exchanger on a chimney for heating a garage is shown in the video. With the help of such a stove you can heat not only a garage, but also any utility room, including agricultural buildings and greenhouses.

From corrugated pipe

A cheap and simple way to install an air heat exchanger is to use corrugated ventilation pipes for this purpose . They are wrapped around the uninsulated part of the chimney, as a result the air in the corrugation warms up and, due to thermal convection, enters the neighboring rooms. To make the corrugated pipe heat up more efficiently, you can wrap it together with the chimney in several layers of foil.

A system with a corrugated pipe is convenient for heating a garage in which a simple potbelly stove made of rough metal is installed. Such a stove quickly heats the air, but it rises to the ceiling, which is why the temperature at floor level remains low. If you move the air ducts closer to the floor, you can create natural circulation of heated air, and the temperature throughout the garage will become approximately the same.

Bell-type heat exchanger

Heat exchangers in the form of a bell are usually used for heating the attic or second floor . The principle of its operation is that the air heated from the chimney rises to the ceiling, where it is retained by the hood and, gradually cooling, falls down into the room.

The cap can be made of either galvanized metal or fire-resistant plasterboard and lead the air ducts to the desired location. Sometimes the cap is decorated with stones, which, when heated, serve as an additional heat accumulator.

Mechanism of operation

A metal stove placed in a house, garage or bathhouse must be equipped with a chimney to remove carbon monoxide and organize draft. During the process of heating the furnace, this pipe can reach very high temperatures, about 200-500 ℃, which is unsafe for people in the room.

If you install a heat exchanger on the chimney, you can significantly increase the efficiency of the stove, and also protect yourself from direct contact with a hot surface. In a tank or coil installed on the chimney, the coolant will be water, however, you can also install an air heat exchanger on the chimney pipe. Due to the direct contact of the chimney with the coolant, their temperature indicators are balanced, that is, the water or air gradually heats up, and the walls of the pipe cool down.

As the temperature of the water inside the register rises onto the pipe, it rises upward, where it enters the water tank through a special fitting. Through the inlet fitting located at the bottom of the heat exchanger, cold water enters it, replacing warm water. This circulation continues constantly, and the water can heat up to very high values.

An air radiator on a chimney pipe has a similar operating principle. Cold air enters the heat exchanger from below, and after heating it rises up and is supplied through the pipeline to the heated rooms. In addition, the radiator fins also give off heat. An air heat exchanger is optimal for heating attics in a country house or dressing rooms of a bathhouse, if such rooms are heated only from time to time. It is not advisable to organize water heating in them, since you will have to constantly fill and drain water from the system.

Briefly about the main thing

The heat exchanger of the sauna stove heats the water during the heating of the structure. Hot liquid accumulates in the outdoor unit. Cold water comes from it. Circulation is carried out according to the principle of gravity and as a result of natural convection.

The two structures are connected by flexible hoses at an angle. Their total length should not exceed 3 m. The external container is always located above the stove. The system must be equipped with a tap for convenient use of hot water.

Connecting an external tank to a bath heat exchanger ensures safe hot water supply in the building. This is a more practical option than a hanging storage structure, which can easily get burned.

Negative points

Along with the benefits of a heat exchanger on a chimney, it is worth noting a number of negative factors. Firstly, due to this design, the temperature of the exhaust gases is significantly reduced. This can provoke excessive soot accumulation, condensation formation and poor traction.

An important point in arranging such a heating system is to calculate how much water is needed for its full functioning. If there is not enough of it, the system may overheat, the water in it will boil, and the pipes may burst. In addition, it is important to ensure the tightness of the seams.

In any case, installing a heat exchanger allows you to increase the efficiency of any furnace. For safety reasons, at least twice a year, visual diagnostics of the system and its maintenance should be carried out - cleaning soot, replacing defective elements, and so on. Then it will be possible to confidently use the heat exchanger for heating the house and heating water in the bathhouse.

Booster Summary

This is very rare and expensive equipment. If you intend to buy it, then you will expect expenses in the range of 40,000 - 90,000 rubles. And for everyday tasks this is a rather unprofitable solution.

The booster itself is a container with a built-in pump that provides a change in the flow vector. Because of this, the efficiency of washing increases significantly. The devices are resistant to any reagents.

The most popular models are presented below:

Booster	A country	Productivity (liters per hour)	Tank volume (l)	Working pressure (bar)	Price tag (RUB)
PIPAL PUMP ELIMINATE 20 V4V	Italy	2600	18	1	38 000
BWT Cillit SEK 28	Germany	2400	20	1,5	57 000
TM Aquamax	Italy	5000	30	1,2	53 500

Step-by-step instructions on how to install a heat exchanger with your own hands

The Kuznetsov heat exchanger is installed instead of one of the chimney sections - for this part of the chimney will have to be dismantled. If a chimney is installed from one long pipe, you will have to cut out part of the chimney and install the structure using welding.

Installation methods

The heat exchanger is installed at a certain distance from the heating unit - 200-500 mm, more is possible.

If the chimney is prefabricated, then it is necessary to disassemble part of the chimney. The heat exchanger pipes are cut so that the length of the heat exchanger structure is equal to the dismantled chimney section. The heat exchanger is mounted in the chimney and sealed using heat-resistant sealant. The top of the heat exchanger is painted with heat-resistant paint.