DHW connection. Installing a plate heat exchanger

Today, the organization of water supply processes is one of the main conditions for creating a comfortable life for citizens. There are several different ways to provide water supply, including the creation of hot water supply systems, but one of the most effective ways today is to heat water through the heating network.

Heat exchangers must be selected based on the conditions of installation and placement, as well as according to user requests and general possibilities for the installation and operation of heating equipment. In most cases, only correct installation and competent calculation allow citizens to forget about interruptions or complete absence of hot water supply.

Device and principle of operation

Modern heat exchangers are units whose operation is based on different principles:

• irrigation;
• submersible;
• brazed;
• superficial;
• collapsible;
• ribbed lamellar;
• mixing;
• shell-and-tube and others.

But plate heat exchangers for hot water supply and heating differ favorably from a number of others. These are flow-through heaters. Installations are a series of plates, between which two channels are formed: hot and cold. They are separated by a steel and rubber gasket, so mixing of the media is eliminated. The plates are assembled into one block. This factor determines the functionality of the device. The plates are identical in size, but located at a turn of 180 degrees, which is the reason for the formation of cavities through which liquids are transported. This is how the alternation of cold and hot channels is formed and a heat exchange process is formed.

Recirculation in this type of equipment is intensive. The conditions in which the heat exchanger for hot water supply systems will be used depends on the material of the gaskets, the number of plates, their size and type. Installations that prepare hot water are equipped with two circuits: one for DHW, the other for space heating. Plate machines are safe, productive and used in the following areas:

• preparation of a heat carrier in hot water supply, ventilation and heating systems;
• cooling of food products and industrial oils;
• hot water supply for showers at enterprises;
• for the preparation of the heat carrier in underfloor heating systems;
• for the preparation of a heat carrier in food, chemical and pharmaceutical industries;
• pool water heating and other heat exchange processes.

Heat exchanger device

Recuperative heat exchangers are used in hot water supply systems. That is, they transfer energy from one medium to another through the anti-mixing surface with constant contact with it.

99% of DHW heat exchangers are water-to-water. That is, they transfer heat from water to water. Rarely - as a rule, for the internal needs of steam boilers, the water in the DHW system is heated by a steam-water heat exchanger (we will describe it too).

By the way, deviating from the topic of our article: At the same boiler houses and CHPPs (combined heat and power plants), steam-water heat exchangers are used to heat the heating water supplied to heating systems. The reason is that steam heating, due to the high temperature of pipes and radiators, as well as the burning of dust on them, is not allowed for residential and public buildings.

Heat exchangers are divided into two groups.

Flowing

This is also almost all, with a few exceptions, heat exchangers used in hot water supply networks. In them, the flow of the coolant, while moving, heats the also moving stream of water for hot water supply.

Capacitive

In hot water supply, as a rule, in such heat exchangers, a moving stream of heating water heats water in a tank, from which it is taken as needed. They are rare. Such devices are not produced commercially.

The advantage of storage tanks is that it is possible to provide a large amount of hot water for a while, even with a low-power heating boiler. Flow-through heat exchangers cannot cope with this task. In storage tanks, the water is constantly heated, and when you need to take a bath or shower, the right amount is taken from the tank.

The disadvantages of such devices are:

1. large dimensions;
2. lower efficiency in comparison with flow-through heat exchangers - part of the heat escapes through the walls of the tank (moreover, they have a large area), even if it is thermally insulated.

If there is a need for more powerful DHWs to operate in a mode similar to that of a storage heater, then a combination is most often used: a conventional flow-through heat exchanger for hot water supply and an insulated storage tank in which hot water is accumulated.

Heat exchanger design

It is difficult to give an exact classification of structures; it may differ from different authors and sources.

But still, most often they are divided into the following groups:

1. sectional;
2. serpentine;
3. shell-and-tube;
4. ribbed;
5. lamellar;
6. lamellar-ribbed;
7. cellular.

In hot water supply systems, in the overwhelming majority of cases, only two types of shell-and-tube and lamellar are used. Let's take a closer look at them.

Shell-and-tube

Shell and tube heat exchangers, grade VVP-1

In them, a bundle of pipes through which the heated water circulates is located in a casing through which the network water passes.

This choice is related to the following:

1. The consumption of hot water is less than the consumption of heating water. Therefore, it is more profitable to let the latter through the annular space.
2. Limescale usually forms from untreated water that we heat. It is easier to clean the inner surfaces of the beam than the outer ones (we will find out why below).

Shell and tube heat exchanger drawing

The body itself is most often steel or cast iron, but the bundle of pipes is made of materials that conduct heat well, because heat exchange takes place through their walls. Therefore, they choose copper or brass, in rare cases aluminum. But you can also find heat exchangers with steel pipes.

Water-to-water heat exchanger design

For even better heat transfer, they resort to other measures:

• They try to make the walls of the pipes as thin as possible. But the thickness is calculated so that they can withstand the working pressure.
• Increase the contact area between heating water and heating water. For this, the pipes are given a complex profile, provided with ribs. The complex profile and ribs give one more advantage - near their walls, the water flow swirls, becomes turbulent (a smooth flow is called laminar). This increases the contact time of its volumes - and, therefore, improves heat transfer.

The types of pipes used in shell and tube heat exchangers are shown in the figure below:

Types of pipes used in shell and tube heat exchanger

• Increase the number of tubes in the bundle and place them as close to each other as possible.
• In order to increase the length of the bundle tubes in the casing, they are not placed in a straight line, but curled into a spiral.

Note: However, all these tricks, in addition to increasing efficiency, also bring a problem - the heat exchanger becomes more difficult to clean. Therefore, half of the machines in use have smooth straight pipes.

At the ends, the casings are closed with washers with holes for pipes, they are called: tube sheets or grids. Moreover, to compensate for temperature deformations, the pipes of the bundle are not welded, but rolled (they also do with pipes in boilers).The options for rolling and positioning pipes on the board are shown in the figure below.

Variants of rolling and placement of bundle tubes on tube sheets (grids)

As a rule, shell-and-tube heat exchangers of hot water supply systems are assembled from several sections, so it is easier to modernize and repair the system. If it is necessary to reduce or increase the power, we simply change their number.

Heat exchanger assembled from several sections

The annular space of the sections, through which the network water circulates, is connected by simple straight pipes. The space behind the tube sheets - U-shaped pipes, also called kalachi. Sections are most often assembled vertically, one above one.

As we have already said, scale forms most of all on the inner surfaces of the bundle tubes. To clean it, thanks to this design, it is not even necessary to completely disassemble the heat exchanger and disconnect it from the heating system. We just turn off and drain the water from the hot water system, remove the rolls and clean the pipes.

Steam-water shell-and-tube heat exchanger

Steam-to-water heat exchanger

As we have already said, such a heat exchanger is less common, and is most often used for the water supply of the steam boiler house itself or nearby houses that do not have their own boilers. Consider it too. A drawing of the most common variety is shown below.

Steam-water boiler

Its design is very similar to the previously discussed hot water heat exchangers. The differences are as follows.

1. The annular space is much larger, since the heating of water for water supply occurs as a result of steam condensation - and this requires volume.
2. The volume behind the left (according to the drawing) tube sheet is divided in two. Water is supplied to one half for heating, and hot water is taken from the second. That is, it moves from left to right along half of the pipes, and from right to left along the other half.
3. The volume behind the right grate is not divided, in which the streams of water unfold.
4. There is a branch pipe for supplying steam from above.
5. The water formed as a result of condensation is taken from the lower branch pipe as the boiler fills. Most often it is returned back to the boiler for reuse.
6. If ordinary boilers are rarely equipped with safety valves (which operate at a critical pressure, releasing it), then for a steam-water apparatus this is a mandatory part.
7. It is also necessary to mount a pressure gauge or other pressure sensor on such a boiler.

Plate heat exchangers

Plate heat exchanger

This type of heat exchanger appeared in the thirties of the last century, they are younger than shell-and-tube devices. But, after a little delay at the start, today they are rapidly pushing out their older brothers.

If even thirty to forty years ago the overwhelming number of hot water boilers were shell-and-tube, today almost all new systems are made with lamellar devices.

Water heating unit with plate heat exchangers

A drawing of such a heat exchanger and a diagram of water flows for various types of assembly are shown in the figure below. This is the most common herringbone design.

Plate heat exchanger and water flow diagram in it

They are a set of plates in which a profile of the strokes is created by stamping (this can be clearly seen in the photo below) for water. And they are trying to make sure that its path is as long as possible. There are four holes along the edges of the plates, two of which are associated with moves, and two are not.

Heat exchanger plate

The plates are assembled into a package using rubber or paronite gaskets in such a way that the cavities between them are connected through one hole.

It turns out a kind of "sandwich":

1. plate;
2. channels through which the network water circulates;
3. plate;
4. channels through which heated water circulates;
5. plate;
6. and. etc.

One of the options for the movement of water flows inside the heat exchanger

Plates, like tubes in shell-and-tube heat exchangers, are also tried to be made as thin as possible, and a metal that conducts heat as well as possible is chosen: copper, brass or duralumin. However, most of the plate heat exchangers are still steel.

The packs of plates and gaskets are restrained by thick steel compression plates, and are compressed by studs and nuts.

Attention. When assembling, always ensure that the clamping is correct so as not to damage the gasket with excessive force and not to distort the plate assembly.

There are also plate-ribbed boilers - in addition to stamped passages, they have ribs to improve heat transfer and increase the cross-section of the channels. But the price for them is an order of magnitude higher, so they are extremely rare in hot water supply systems.

The advantages of such devices include:

• Compactness: a plate heat exchanger for hot water supply with equal power with a shell-and-tube heat exchanger takes up 2-3 times less space.
• You can easily increase or decrease power by adding or removing shim plates. Shell-and-tube boilers have the ability to regulate the power only in whole sections, which are interconnected by rolls and nozzles.
• Cheap repair, replacement of the plate and gasket costs a penny.

But there are also disadvantages compared to shell-and-tube:

• Plate heat exchangers cannot operate at high pressures.
• They are sensitive to water hammer.
• Plate heat exchangers have a higher flow resistance. In systems without forced circulation of network water, they may not work very correctly.

High pressure leaking plate heat exchanger

Connecting heat exchangers

Next, we will consider how heat exchangers are connected to the heating system and hot water supply. There are three most common options. And it doesn't matter which boilers are used - plate or shell-and-tube.

Connection without hot water recirculation

The simplest heat exchanger connection diagram is shown in the figure below; it is usually used in the DHW system of a small private house with an autonomous heating boiler.

Heat exchanger connection diagram without hot water recirculation

It is done as follows:

1. The heat exchanger is connected in parallel with the heating devices. Moreover (we have already talked about this), the network water is supplied to the shell-and-tube boiler shell-and-tube space. In plate devices, the circuits are completely identical, so it does not matter which one of them is connected to the heating network.
2. Cold water is supplied to one of the nozzles of the second circuit of the heat exchanger from the water supply, and hot water is taken from the other.
3. The water in the heat exchanger moves due to the pressure of the water supply.

This figure also shows the connection diagram for the hot water temperature controller.

It is also as simple as possible:

• A temperature sensor is installed on the heat exchanger. On the diagram, it is designated B3 and the number "5". It can also be installed at the hot water outlet.
• The signal from it goes to the microcontroller. In this scheme, it also regulates heating, but this is not important to us.
• Analyzing the data received from the sensor, the microcontroller gives commands to the gate valve electric drive (it is designated Y The drive is labeled 9.
• The valve is mounted on the return line of the network water (the return line is called the pipeline in which the water returns to the boiler - the line from the boiler is called the supply). By reducing the water consumption, they lower the temperature, while increasing it, they raise it.

However, this connection scheme is not very convenient. If the pipelines are long enough, you will have to wait a long time for the cold water to drain and hot water to go.Therefore, usually hot water pipelines are looped back and recirculation pumps are installed. Then hot water is constantly moving in a circle. A similar scheme is discussed below.

DHW circulation pump

Hot water recirculation connection

Scheme for switching on a heat exchanger with hot water recirculation

If you have not yet met with heating network diagrams, then this diagram indicates:

1. T1 - supply of heating water from the boiler.
2. T2 - return of the heating system.
3. T3 - hot water supply.
4. T4 - hot water return.
5. В1 - cold water supply from the water supply system.

These alphanumeric designations are generally accepted, and are found on all diagrams of thermal systems.

Further, the numbers in the footnotes indicate:

1. heat exchanger for hot water supply;
2. temperature controller (2.1 is a valve, 2.2 is a sensor that controls the valve);
3. recirculation pump;
4. water meter;
5. device protecting the pump from dry running.

Valves and gate valves are designated by two triangles directed towards each other. If one of the triangles is filled, then this is a check valve that lets water through in only one direction.

There are two of them in this scheme. One - after the water meter and connecting the water supply, they are mounted so that the recirculation pump does not transfer hot water from the return to the water supply. The second non-return valve is located after the pump, and additionally protects it from dry running.

In this scheme, the returned hot water is mixed with cold water, which is not very beneficial.

Two-stage connection diagram

If hot water supply systems with a heat exchanger are designed for a large analysis of water, then in order to reduce the size of the equipment, two-stage heating is used. This is how they almost always mount hot water supply for an apartment building with a centralized heating system.

Note: Often, boilers work not even for one building, but for a group of them - then they are placed in central heating points (CHP).

The heat exchanger connection diagram for it is given below.

Connection diagram for heat exchangers for two-stage water heating

The designations in this diagram are the same as in the previous one. Its upper part is also similar to that previously considered - the only difference is that not a water supply is connected to the hot water return (T4), but supply from another heat exchanger (1 stage), to which the water supply (B1) is connected. Thus, it is not cold water that is mixed into the water circulating through the hot water system, but preheated water.

A valve to protect against crushing the hot water supply system is installed in front of the first stage. The temperature regulator is placed on the second stage.

Connection diagrams

If you decide to use a plate heat exchanger for heating and hot water supply in the system, then before selecting a specific model, you need to consider the type of connection diagram. There are three options:

• Independent configuration of the connection from the heat supply (this is how the boiler is connected).
• Parallel or 1-stage configuration involves the installation of equipment in parallel with the heating communication. Regulation is carried out by one valve. The process is a constant fixation of the specified temperature of the medium. This is a simple structure that provides sufficient heat exchange, but consumes large volumes of coolant and involves the connection of pumping stations. This circuit is economical to install.
• The two-stage configuration guarantees efficient use of backflow energy. Liquid preparation is carried out in 2 units. The first heats the water up to 40 degrees, the second continues the procedure and brings the indicators to the specified rate. This is +60 degrees. The second DHW plate heat exchanger can be connected in parallel or in series, depending on the chosen engineering scheme. This method is characterized by low heat carrier consumption - up to 40% and high efficiency. This arrangement will provide operational savings.

Operating costs and whether people will receive a sufficient amount of hot water depend on the competent choice of the connection scheme. But in order for the circuits to be efficient, it is necessary to correctly select a heat exchanger for heating. The parameters take into account the combination of the hydraulic regime of water supply and heating.

Types of heat exchangers for hot water systems

Among the many types of various heat exchangers in domestic conditions, only two are used - plate and shell-and-tube. The latter have practically disappeared from the market due to their large dimensions and low efficiency.

Lamellar DHW heat exchanger

is a series of corrugated plates on a rigid bed. All plates are identical in size and design, but mirror each other and are separated by special spacers - rubber and steel. As a result of strict alternation between the paired plates, cavities are formed, which are filled with a coolant or a heated liquid - mixing of media is completely excluded. Through the guide channels, two liquids move towards each other, filling every second cavity, and also, along the guides, leave the heat exchanger giving / receiving thermal energy.

The higher the number or size of plates in the heat exchanger, the larger the area of ​​useful heat exchange and the higher the performance of the heat exchanger. On many models, there is enough space on the guide rail between the bed and the striking (outer) plate to accommodate several plates of the same size. In this case, additional plates are always installed in pairs, otherwise it will be necessary to change the inlet-outlet direction on the blocking plate.

Scheme and principle of operation of the DHW plate heat exchanger

All plate heat exchangers can be divided into:

• Collapsible (consist of separate plates)
• Brazed (sealed case, not collapsible)

The advantage of gasketed heat exchangers is the possibility of their modification (adding or removing plates) - this function is not provided in brazed models. In regions with poor tap water quality, such heat exchangers can be disassembled and cleaned of debris and deposits by hand.

Brazed plate heat exchangers are more popular - due to the lack of a clamping structure, they have more compact dimensions than a collapsible model of similar performance. selects and sells brazed plate heat exchangers of leading world brands - Alfa Laval, SWEP, Danfoss, ONDA, KAORI, GEA, WTT, Kelvion (Kelvion Mashimpex), Ridan. From us you can buy a DHW heat exchanger of any performance for a private house and apartment.

The advantage of brazed heat exchangers in comparison with gasketed ones

• Small size and weight
• Stricter quality control
• Long service life
• Resistant to high pressures and temperatures

Brazed heat exchangers are cleaned CIP. If, after a certain period of operation, the thermal characteristics begin to decrease, then a reagent solution is poured into the apparatus for several hours, which removes all deposits. The break in the operation of the equipment will be no more than 2-3 hours.

How to calculate a model for a specific building

In order for the heat exchanger to be effective in the heating and hot water supply system, the following parameters must be taken into account when choosing:

• number of consumers;
• the volume of water required by 1 consumer per day (for information, according to SNiP, the limit is set at 120 liters per person);
• heating of the coolant, in central networks its temperature averages 60 degrees;
• the device is constantly in use or will be turned off - operation mode;
• average temperature values ​​of cold water in winter;
• permissible heat loss, standard value - 5%;
• the number of plumbing fixtures to which the DHW is connected.

For calculations, other data will also be required, depending on the situation and conditions. The result of this calculation will be a model that will be able to supply the required volumes of hot water for a specific dwelling.

Strapping scheme

The heat exchanger is connected to the heating system in several ways. The simplest version with parallel connection and the presence of a control valve powered by a thermal head.

Shut-off ball valves at all outlets of the heat exchanger are mandatory in order to be able to completely shut off the access of liquid and provide conditions for dismantling the equipment. The power control and, accordingly, the heating of hot water should be handled by a valve controlled by a thermal head. The valve is installed on the supply pipe from the heating, and the temperature sensor is installed on the outlet of the DHW circuit.

With the cyclical organization of hot water supply with the presence of a storage tank, an additional tee is installed at the inlet of the heated circuit to turn on cold tap water and return through hot water supply. A check valve will prevent unnecessary flow in the opposite direction in the hot and cold water branch.

The disadvantage of this scheme is the greatly overestimated load on the heating system and ineffective heating of water in the second circuit with a large temperature difference.

The scheme with two heat exchangers, two-stage, works much more efficiently and reliably.

1 - plate heat exchanger; 2 - direct-acting temperature regulator: 2.1 - valve; 2.2 - thermostatic element; 3 - DHW circulation pump; 4 - hot water meter; 5 - electro-contact pressure gauge (protection against "dry running")

The idea is to use two heat exchangers. In the first stage, the return flow of the heating system is used on one side, and cold water from the water supply system on the other. This preheats about 1/3 or half of the required temperature without affecting the heating of the house. The circuit is switched on in series with the bypass, on which the needle valve is already fixed, with the help of which the volume of the coolant is regulated.

The second PHE, the second stage, connected in parallel with the heating system, is, on the one hand, the supply of hot coolant from the boiler or boiler room, and on the other hand, the DHW water already heated at the first stage.

There is no need to deal with the adjustment of the first stage. Only ball valves are installed on all four outlets and a check valve for cold water supply.

The piping of the second stage is identical to the parallel connection, except that instead of cold water, already heated water from the first stage is connected.

The organization of hot water supply is one of the main conditions for a comfortable life. There are many different installations and systems for heating water in a domestic hot water network, but one of the most effective and economical is the method of heating water from the heating network.

Heat exchanger for hot water

is selected individually, based on the owner's requests and the capabilities of the heating equipment. Correct calculation and competent installation of the system will allow you to forget about interruptions in hot water supply forever.

Selection of heat exchange equipment for hot water supply

If the engineering calculation of heat exchangers for heating and hot water supply was done correctly, and a correctly selected model of equipment is installed in the building, taking into account the operating conditions, you can count on the reliable operation of the equipment for 15 years. Do not neglect the services of professional craftsmen, this will form additional guarantees of system performance and security.

On the Russian market, there are installations from well-known brands and Russian-made plate heat exchangers, the latter are no less reliable, but affordable. So, the heat exchanger for the Ridan hot water supply system (Danfoss group of companies) is in demand, even wealthy consumers prefer to buy it. Therefore, it is better to choose a device not according to the brand name, but according to the parameters of a specific structure and technical characteristics of the device. Better if done by a professional.

Use of plate-type heat exchangers to provide DHW

This method is good in that there is a useful use of the heat of the return water, and also in that the circuit is compact.

In the new heat exchanger, this is achieved by increasing the number of plates of the same area.

The diagram shows a plate heat exchanger for heating of the simplest design with nozzles located on different sides of the unit. The heating is no longer quite cold, but warm.

In systems with natural circulation, this type of installation is ineffective. In IHP Dependent heating connection with automatic heat consumption control.

It is also important that no one is able to give guarantees that these calculations will be percent correct. It is advisable to install the same filter at the cold water inlet - the equipment will work longer. As a result, the cost of hot water per liter will be much lower. The plates of the plate heat exchanger are positioned one after the other with a rotation of degrees.

Their structure is more complex, the cost is higher, but they are able to take maximum heat with high efficiency. The plate heat exchanger assembly scheme is not complicated, the upper and lower guides are fixed on a tripod and a fixed plate. Connection diagrams of PHE Connection diagrams of plate heat exchangers Here you can find out what are the diagrams for connecting plate heat exchangers to communication networks. Due to its small size and weight, the installation of the heat exchanger is quite simple, although powerful units require a foundation.

Let's talk in more detail about the most affordable, reliable and effective ones. The power depends on the total heat exchange area, the temperature difference in both circuits between the inlets and outlets, and even on the number of plates. With this scheme, water preparation takes place in two steps. The piping of the second stage is identical to the parallel connection, except that instead of cold water, already heated water from the first stage is connected.

Their structure is more complex, the cost is higher, but they are able to take maximum heat with high efficiency. In accordance with the rules, in addition to the working pump, a reserve pump of the same power is installed in parallel. The experience and skills of specialists allow both to perform the simplest calculations and complex installation with a start-up plate. Then the plates are made of titanium, nickel and various alloys, and the spacers are made of fluorine rubber, asbestos and other materials. It should be noted that shell-and-tube systems have almost disappeared from the market due to their low efficiency and large size. Plate heat exchanger working principle

Direct heating technology

It has been said about indirect heating of water, but there is another heating technology, which is called direct. That is, the heat exchanger in the hot water supply system is installed directly into the furnace of the heating boiler. That is, the device is heated directly by the energy carrier. As practice shows, in such a DHW system, units of a combined type are usually installed. at the heart of their design is a pipe coil, along which cold water moves. And to enhance heat intake, plates are additionally installed, thereby increasing the intensity of heat intake. The photo below shows such a unit. By the way, these devices are called primary.

Primary heat exchanger

They are most often made either from stainless steel or from a copper alloy. It should be noted that this type of heat exchanger is subject to heavy loads. This is not just about temperature. The thing is that processes occur inside the pipes under the influence of high temperature, which lead to the rapid deposition of minerals and various salts on the walls. And this is a decrease in the diameter of the pipe, and as a result, a decrease in the intensity of heat transfer towards the water passed through the pipes. Therefore, it is very important, when operating the plumbing system of a private house, to pay attention to the quality of the water taken from a well or well. And the simplest thing in this case is to install a filter for different purposes, that is, to organize correctly a water treatment system.

There is another option associated with heating water for hot water supply. This is the installation of a tank on the chimney of a heating boiler. In principle, the function of the heat exchanger here will be played by the chimney, on which the water tank will be installed and fixed. Such a design of a heat exchanger for hot water supply of a private house is quite effective, and at the same time very economical. That is, there are no complex devices and structures here. True, it is necessary to pay attention to the material from which part of the chimney will be constructed. In this case, it is best to use stainless steel pipes. They not only easily cope with corrosive processes, but also withstand high temperatures well, under the influence of which they do not warp and do not burst. True, such a chimney will cost a lot. And this, in principle, is the only drawback of the device.

Installing a heat exchanger in the furnace

DHW Plate Heat Exchanger Application

Heating water from the heating network is completely justified from an economic point of view - unlike classic water heating boilers that use gas or electricity, the heat exchanger works exclusively for the heating system. As a result, the final cost of each liter of hot water is an order of magnitude lower for the homeowner.

A plate heat exchanger for hot water supply uses the thermal energy of the heating system to heat ordinary tap water. Heated from the heat exchanger plates, hot water flows to the points of water intake - taps, faucets, shower in the bathroom, etc.

It is important to take into account that the heating water and the heated water do not contact in any way in the heat exchanger: the two media are separated by the plates of the heat exchanger, through which heat exchange is carried out

.

It is impossible to directly use water from the heating system for domestic needs - it is irrational and often even harmful:

• The process of water treatment for boiler equipment is a rather complicated and expensive procedure.
• To soften water, chemicals are often used that have a negative impact on health.
• Over the years, a colossal amount of harmful deposits accumulates in heating pipes.

However, no one indirectly forbade the use of the water of the heating system - the DHW heat exchanger has a sufficiently high efficiency and will fully satisfy your need for hot water.