You can connect a gas boiler to an indirect heating boiler in various ways. The task of a storage type water heater is to heat and have in stock the required amount of water for hot water supply. The boiler must have time to provide heating appliances and a heater with thermal energy, for which it must have a certain power reserve. The method of tying the boiler depends on the complexity and branching of the heating network at home. To choose it correctly, it is worth studying the drawings of several piping schemes for both units.

Parallel connection of units

The simplest parallel scheme for connecting an indirect heating boiler to a natural gas heat source is appropriate in such situations:

• the boiler is wall-mounted and equipped with its own circulation pump;
• the heating system is simple, consisting of the same type of heating devices - radiators or underfloor heating;
• the water heater is small.

Parallel piping of the boiler is simple: the upper branch pipe of its heat exchanger is connected to the supply line of the gas boiler, and the lower one is connected to the return line. As a result, the circulation of the heat carrier through the heating system and in the heat exchanger of the water heater occurs simultaneously and up to the same temperature. Its regulation is carried out on the boiler, which creates a lot of inconvenience:

It follows that a simple parallel connection of an indirect heating boiler to a heat generator is suitable for a small house with a small number of radiators.

Connection method with a separator node

A three-way thermostatic valve is used to connect an indirect heating boiler with separation of heat carrier flows into heat supply and hot water supply. It is installed on the supply pipe from the boiler, and the branch to the water heater is connected to the valve outlet, which is initially open. The three-way valve is controlled by a remote temperature sensor. With this connection option, a gas boiler with a boiler works according to the following algorithm:

1. At first, when the coolant is heating up, the circulation provided by the boiler pump occurs only in the water heater circuit. The three-way valve directs the entire flow to provide hot water.
2. Upon reaching the required temperature in the DHW circuit, the sensor is activated and causes the three-way valve to direct the flow to the heating system, and close the outlet to the water heater.
3. When the temperature in the tank drops or there is a drawdown in the DHW network, then, at the signal of the sensor, the separating valve redirects the coolant to heat the water in the boiler.

Although some of the shortcomings of the previous connection scheme have been eliminated here, this method is still suitable only for simple systems with the same types of space heating. The alternating operation of the water heater and batteries allows them to operate more efficiently, the main thing is that the boiler has enough power. But, since the boiler is in priority over the radiators, at high flow rates in the DHW system, the heat generator may not have enough time to heat the water in the heating network. Therefore, with a large number of people living in the house, such a scheme for connecting the boiler to the boiler can create inconvenience.

Connection with two pumps

An important advantage of this strapping method is the ability to function in the summer and provide the house with hot water when the heating is not working.

When the elements are mounted correctly, a three-way valve is not required, the flow is redirected by turning on the circulation pumps one by one.

Each of them is controlled by an overhead thermostat that records the temperature of the water in the water heater tank. If it is insufficient, then the pump of the water heating circuit works, the coolant works for the needs of hot water supply, and the circulation in the heating network is suspended. When the set temperature is reached, the thermostat switches off the DHW circuit pump, after which the heating pump unit starts.

When the area of ​​​​the cottage is large and it is heated by various systems - radiators, underfloor heating and baseboards, then it will not work to connect a single-circuit gas boiler and a storage water heater in parallel. An extensive network with several circulation pumps providing separate heating branches requires the installation of a hydraulic separator with a distribution manifold. An indirect heating boiler is attached to it, moreover, with its own pumping unit.

With this option, it is also customary to connect the pump for the boiler through a thermostat in order to save energy and not take the coolant away from other heating circuits. Such a scheme has the following advantages:

• a single-circuit boiler correctly selected in terms of power will provide the necessary amount of heat to all heating branches, including an indirect heating boiler;
• each branch is isolated and hydraulically separated from the heat generator, so the heat network does not affect the operation of the water heater and vice versa;
• the circuit will always work stably, even with a large drawdown in the DHW network, organized with hot water recirculation.

These advantages arise due to the use of expensive equipment in the strapping. Hence the disadvantages of the scheme - the high cost and complexity of installation, but a country cottage of a large area and inexpensive heating are incompatible concepts.

How not to tie equipment?

There is a widespread opinion that the connection of a boiler to a double-circuit boiler can be performed by docking the DHW circuit of the heat generator with an indirect water heater. There are 2 options for the development of events:

1. The family uses a double-circuit gas heater, but the owner is not satisfied with its performance. Then he buys an indirect heating boiler and connects it to the secondary circuit of the boiler, using an additional circulation pump.
2. The initially misled homeowner purchases a storage water heater together with a double-circuit heat generator and ties them up as described above.

This method of docking the units is erroneous and will not lead to an increase in the hot water capacity of the system. The reason is the limited capacity of the secondary heat exchanger of the boiler, designed to deliver 7-12 liters per minute of water heated to 30-35°C. While the capacity of the water heater tank is from 100 liters, and this volume of water needs to be heated to 50-55 ° C.

During the time that the boiler is heating up, the heating system will remain without heat and the building will begin to cool down. When the boiler finally switches to heating, it will have to work at maximum for a long time in order to restore the microclimate in the house. Therefore, the scheme for connecting a double-circuit heat generator to an indirect heating unit is no different from piping with a single-circuit boiler.

Moreover, you do not need to buy a dual-circuit heat source to work with a boiler. A single-circuit gas boiler of a suitable type is appropriate here. The best option recommended by experts is that both units are made by the same manufacturer.

Heating in a private house, and indeed heating water in it, is something that must be equipped in order to live in comfortable conditions. And the more economically the process of heating water is organized (and in this case one cannot do without such equipment as BKN), the better it will be for the owner of the cottage, because this will reduce the cost of funds. Connecting an indirect heating boiler to a single-circuit boiler is not an easy task, but it can be completely solved independently. The main thing is to figure out how it's done.

Indirect heating boiler - what kind of unit?

This phrase means a tank filled with water, which is inside equipped with a heat exchanger coil connected to a boiler responsible for heating the house, or to another system inside which some kind of coolant circulates. The water in such a unit becomes hot due to the fact that the liquid coming directly from the boiler into the heat exchange coil gives up its energy to the liquid, which is located in the boiler tank itself. That is, it does not heat up directly, but only absorbs heat from another source. Hence the name for this unit was formed - an indirect heating boiler.

The water heated in the unit can be used for a variety of household needs. Moreover, it remains in a heated state for a long time, since the system itself maintains the desired temperature level. By the way, you can install such a boiler not only in a cottage, but also in an apartment, hotel or other premises.

The boiler itself is a metal or plastic container of a parallelepiped shape or a cylindrical one. The capacity of the tank can be anything and sometimes amounts to thousands of liters.

On a note! The tanks of some units can be coated on the inside with glass-ceramic, enamel or other materials that help keep the water in proper quality and protect the metal of the tank from corrosion.

The water tank is usually enclosed in another casing, and thermal insulation material is often laid between these two structural elements. It helps to retain heat longer and also protects the outer shell of the tank from extreme heat. Water, which is directly responsible for heating the liquid in the boiler tank, usually circulates through a heat exchange coil. The elements of the tank are protected from corrosion by the presence of a magnesium anode. To control the pressure in the unit, the installation of a so-called safety valve and thermostat is provided. Water circulation occurs due to the presence of a special system of pumps.

So BKN is a kind of "thermos" for water in the house. It does not heat the water itself, but is able to keep the liquid heated by the coolant in a warm state.

Advantages, disadvantages, types of equipment

How good is this boiler? The most important thing is that the water in it can be heated at no extra cost. That is, you will not have to pay extra for electricity or gas, unlike the same direct heating boilers that have special heating elements such as burners in their design. Boiler KN uses a ready-made resource of the heating system in the house.

This aspect also allows us to talk about a reduced load on the power grid in the house. At the same time, the performance of the boiler is quite high, it is safe and able to serve for many years without any complaints, because its inner part is even protected from contact with running water. Water from such a boiler is supplied to the consumer as soon as it is needed.

Of course, the equipment has its downsides. First of all, this is a high cost - it costs more than a direct heating boiler. It is also worth understanding that the water in it heats up longer, but it also stays hot longer. Yes, and such a boiler takes up a lot of space, it is better to put it in a separate room. And one more main drawback - in the summer, in order to heat the water, you will have to start the heating boiler.

On a note! There are several types of indirect heating boilers. Let's see how they differ from each other.

Table. Types of boilers KN.

View	Description
	Such heaters are connected to boilers that do not have control. Usually they are equipped with a special sensor that allows you to control the temperature of the water, and also allow you to accurately control the on and off of the fluid supply to the so-called coil - to the coolant circuit. It is easy to connect such a boiler - just connect the supply and return of water from heating the house, as well as connect the supply of cooled liquid and the distribution of heated hot.
	Such tanks are usually connected to a system equipped with an automated boiler. When installing, it is important to think about mounting the temperature sensor and install it in the housing, then connect it to the boiler.
	As you might guess, such a boiler is mounted on the wall. Usually it is small in size, so that a lot of water does not heat up in it. It is important to understand that the boiler is not an easy construction, and the wall on which it will be mounted must be strong.
	This option is placed on the floor and can have different sizes and capacities. It is rarely used in residential buildings - such a boiler can often be seen in industrial premises. They put him in a separate room.
	The most common option, as it allows you to competently save space in the room. But such a boiler does not have a large capacity.
	This is usually a large enough boiler that will hold a lot of water. Often used in enterprises.

On a note! It is important to understand that the smaller the boiler, the faster the water will heat up in it. Although modern designs sometimes allow you to heat a large amount of water in a very short time.

Boiler selection KN

The choice of such a unit as an indirect heating boiler must be approached with all responsibility and, first of all, ask yourself the question: “Will it be convenient to use such a device?”. The pros and cons of the unit are described above. In this section, we will note several aspects that you need to know in order to understand whether you should buy it. They will also help you choose the most suitable version of the KN boiler.

It is also better to take boilers that have some protection elements - safety valves, thermostats, etc. Do not be lazy and refuse to fill out a warranty card in a store upon purchase. The boiler is expensive, and it will be a shame, having acquired it, to be convinced of the inadequate quality of the goods. And it is difficult to change such equipment without a warranty.

Connecting the BKN unit to a boiler with one circuit

You can connect such a unit to boilers of various types - single-circuit, double-circuit gas, solid fuel boilers, etc. The connection is made according to various schemes and it is important not to violate them, otherwise you can not only create a dangerous environment for hot water users, but also completely remove the system out of service. It is best if the boiler is connected by a person who has special skills. But with careful familiarization with the connection diagram, you can do all the work yourself.

A single-circuit water heater is more common than other types. So we will consider connecting the BKN specifically to a single-circuit boiler. There are several methods.

Three way valve system

If a family needs a large amount of warm water, then it makes sense to think about this type of connection. Here, the priority will be heating tap water. The whole system consists of two heating circuits, where one of them heats the water in the BKN tank, and the other is directly responsible for heating the house. Water flows are distributed precisely through the presence of a three-way valve, which is easy to control using a thermostat. It is important to correctly adjust the latter - the temperature of the heating of the liquid in the unit must always be lower than the temperature of the water that heats it directly. Otherwise, distribution of flows will not occur.

The valve is mounted at the outlet of the water from the boiler. And he is responsible just for switching the direction of flows. That is, if the water in the tank has cooled down, then the valve will switch to the DHW system, and if it is hot enough, the valve will send the coolant to the house heating system.

Important! If the thermostat is set incorrectly, that is, the temperature is set too high, the valve will always direct water to the hot water supply, and not redistribute it between the water supply and heating.

Two circulation pumps

This option is suitable for those who are not going to use the BKN all the time. In this case, two circulation pumps will be installed at once - one will go to the operation of the heating system, the second - to supply liquid to the boiler tank. Then it turns out that the coolant itself is constantly circulating in the heating system of the house. One of the pumps (on the boiler) is connected to the temperature sensor and, as soon as the liquid in the water supply pipes cools down, a signal is given to indicate this. Then pressure is created, which can change the direction of movement of the coolant and send it to the boiler. It turns out that the coolant runs through different pipelines thanks to specially installed pumps.

Important! To prevent the coolant from mixing, you need to put a check valve in front of each pump.

The difference between this scheme and the previous one is that the thermostat controls the operation of two pumps at once. That is, if the pump is working to supply water to the user, then the heating pump is turned off.

hydraulic arrow

This option is optimal if in the house, in addition to the boiler itself, as well as heating, there is a water-based floor heating system or a wall heating system. That is, here it is necessary to redistribute several streams of water at once. This circuit is highly complex, so there can be no question of its independent connection.

Features of connecting BKN

KN boilers can be connected in different ways, but there are still general principles for performing such work.

An example of connecting the BKN to a single-circuit boiler

Step 1. The first step is to mount the entire heating system and connect it to the distribution manifold system and the heating boiler.

Step 3 A thermal relay must be installed on the BKN body, which will help to set the desired water temperature.

Step 4 Behind the boiler itself, you need to connect all communications. These are pipes for supply and output of water. To the uppermost outlet, you need to connect the hot water outlet for consumption through a shut-off valve.

Step 5 The intake of heated water in this boiler model can be carried out from above the boiler or behind the top outlet. Here it is necessary to install a Mayevsky air vent valve in the upper outlet.

Step 6 The next way out is to connect hot water recirculation. Here it is important to mount a check valve, directly the recirculation pump itself and a ball valve. A system equipped in this way, in the presence of a ball valve, will, if suddenly necessary, turn off the flow of water and repair or replace the pump. The equipment turns off when the liquid has warmed up to the temperature desired by the user. When the water cools down, the pump will turn on again. In general, recirculation is required so that hot water is always immediately supplied from the boiler, without a small amount of cooled water dripping. It also allows you to connect heated towel rails.

Step 7 Below the recirculation equipment, it is required to connect directly the water supply from the heating pipes to the coil circuit inside the boiler. A pump, a check valve and a shut-off valve are also mounted.

Step 8 At the bottom, you need to connect the return pipes, which will bring the water coming from the heating system back out of the boiler chamber.

Step 9 The cooled water enters the boiler chamber through the lowest pipe. Here you need to mount a tap, then a safety valve, as well as a special expansion tank. The last element you need to buy is the one that is suitable for water supply, and not for heating.

Step 10 After the connection point of the expansion tank, it is also necessary to install a check valve in this part of the communications.

Step 11 A stopcock should also be installed on the drain of the tank and drained into the sewer.

Video - How to connect a KN boiler to a single-circuit boiler?

Video - Tying a single-circuit boiler and boiler

Connecting a KN boiler is not as easy as it seems. Moreover, the main difficulty lies precisely in pairing all the indicators of the purchased equipment. And the rest, where and how to connect the supply and return pipes and the rest, is not so difficult to figure out. But in the absence of proper experience, it is better not to install the boiler yourself, but to invite specialists.

Indirect heating boilers are actively used in everyday life as productive devices for convenient and safe preparation of hot water. Using heat from traditional heating pipes for power, they are economical. The indirect heating boiler is connected using several schemes described in this review - we will consider both complex and simple schemes. At the same time, we will figure out how to make the electrical connection of this unit.

Design of an indirect heating boiler

Electric storage water heaters are gradually becoming more and more common sources of domestic hot water, using a conventional household power supply for power. They are equipped with conventional heating elements responsible for heating water in internal tanks. Electricity costs are not the largest, but not the smallest either - the larger the boiler, the higher the consumption. But in the world of water heaters, there is a more economical technique.

Indirect heating boilers use heat extracted from heating systems to heat hot water. To do this, they are equipped with metal coils. With a solid area, they quickly heat the water to the temperature set on the panel. Temperature control is supported by built-in or plug-in automation.

The scheme for organizing the DHW circuit using capacious wall and floor boilers of indirect heating has the following advantages:

• Savings on electricity - in winter it will be tangible;
• Rapid preparation of hot water - "indirect" are characterized by high performance;
• High reliability - many specialists tend to use just such a scheme, and not double-circuit boilers.

The scheme is really simple and reliable, it remains only to select and connect the indirect heating boiler to the heating system. Let's see how to connect.

Basic wiring diagrams

In our review, we will consider some of the most popular schemes for connecting indirect heating boilers to heating equipment. They differ in their degree of complexity, so you have to choose the best option.

Connection without regulation

This scheme is characterized by maximum simplicity, but is practically not used in hot water supply systems. Yes, we can safely connect an indirect heating boiler to a gas boiler without additional piping. But you have to somehow put up with the lack of the ability to adjust the temperature to your liking. In fact, the temperature of the water in the tank with such a connection scheme depends on the temperature of the coolant at the connection point.

Remember that the maximum temperature of the water in the tank of the indirect heating boiler (water heater) is only a couple of degrees lower than the temperature in the heating circuit.

In some cases, the coolant (water) in heating systems is heated to high temperatures, up to + 70-80 degrees. More impressive figures are also recorded. Such powerful heating leads to the fact that the temperature of the water in the water heaters jumps to similar levels. We open the tap, and hands are scalded with almost boiling water. Agree that such a connection is not safe, even if you dilute the water with a mixer.

Thus, the connection diagram for an indirect heating boiler must necessarily contain regulatory elements. Temperature stability at the outlet will avoid problems with scalding hands and other parts of the body. Moreover, most connection methods are relatively simple.

Connection with circulation pump

Connecting an indirect heating boiler to a single-circuit boiler using a low-noise wet-type circulation pump is one of the simplest schemes. It uses the following nodes:

• Circulation pump - provides forced supply of coolant to the inside of the water heater (to the tank);
• Thermostat for indirect heating boiler - built-in or external;
• Check valve - prevents the reverse flow of the coolant and stops circulation when the pump is turned off.

Let's take the simplest case, when there is already automatic equipment in the water heater. For installation, we need a piping for an indirect heating boiler, which includes the following elements - a tap for quick disconnection from the heating system, a circulation pump, a check valve, a shut-off valve from the water supply, a check valve for the water supply.

We begin work on the connection - we install our indirect heating boiler in a given place (floor or wall mounting). Next, we lead the pipe to the heating system, we connect through the tap. We install a circulation pump at the outlet of the water heater, and after it we put a check valve.

A gas boiler with an indirect heating boiler is a simple and reliable link for organizing a durable and productive DHW circuit. To connect the water heater, we can use one simple circuit using a three-way valve. It will play approximately the same role here as in a conventional double-circuit boiler - there it switches the movement of the coolant from the heating circuit to the secondary heat exchanger, in which the water is heated (when the tap is opened).

It works the same way here. To organize the connection, we need a three-way valve, a low-power circulation pump and the indirect heating boiler itself. The circulation pump is common here, it drives the coolant through the heating circuit and through the water heater. And this process is controlled by a three-way valve connected to a thermostat. As soon as the temperature in the tank falls below the norm, the valve switches and the heating of the water in the DHW circuit begins.

No need to think that when the water is heated, the temperature in the house will start to drop - the water heats up quickly, your household will never have time to cool down. After all, it does not cool down during the operation of the DHW circuit in double-circuit boilers.

The hydraulic arrow allows you to connect to the boiler with optimal distribution of the coolant. Radiators, underfloor heating systems, as well as indirect heating boilers are connected to its outlets. Each direction contains its own circulation pump. Another pump is installed between the hydraulic arrow and the pump.

Similarly, the connection is made through distribution manifolds. As in the case of the hydraulic arrow, each direction has its own circulation pump. The advantage of this connection method is the temperature uniformity in the outlets for each direction. The indirect heating boiler is connected to the hot collector, and the cooled coolant leaves it into the cold collector. A non-return valve is installed at the outlet of the boiler, the circulation pump is at the inlet.

The scheme for connecting an indirect heating boiler with recirculation suggests the following convenience - you open the tap, and hot water immediately starts to flow from it. Usually everything happens exactly the opposite, since the pipe section from the water heater to the tap itself could have cooled down. The result of this is that when the tap is opened, a cold year flows out of it, heating up only after a few seconds. The longer the pipe, the longer it takes to heat up.

Recirculation of hot water through an indirect heating boiler avoids this unpleasant phenomenon. When connecting, it is necessary to implement the following scheme - take the pipe from the tap back to the boiler. A circulation pump is also installed in the hot water supply system. Thanks to this, the pipe to the faucet contains hot water all the time. More detailed information will be given by the drawing of this connection method.

For the system to work, you will need to purchase an indirect heating boiler with recirculation support.

How to choose the right connection

An indirect heating boiler can even be connected to a double-circuit boiler, if it makes sense - for example, such a scheme will allow you to connect many draw-off points and use them at the same time. Here we select any available scheme. In the absence of underfloor heating and several heating circuits, the best solution would be to connect through a circulation pump or a three-way valve.

If you need to create a connection diagram for a solid fuel boiler that runs on wood, we recommend choosing the option shown in the picture below. Here the priority of the indirect heating boiler is used. The coolant for heating devices is taken from its outlet. This connection reduces the heat load on the radiators and ensures a reliable supply of hot water.

Connection through hydraulic arrows and collectors is used if it is necessary to provide a building of impressive size with heat and hot water. For example, it can be a two- or three-story cottage. In this case, a powerful boiler is installed in the system, distribution equipment is connected to it.

Electrical connection

In the warm season, the equipment is turned off, so you need to somehow solve the problem with hot water. To do this, we can close the heating circuit and leave only the indirect heating boiler to work. But most often, a simple connection of the water heater to the mains is practiced - for this, heating elements are mounted here (in some models they are built in initially). It is necessary to connect to the mains through circuit breakers.

Video

In order to avoid problems with hot water, no sudden shutdowns, interruptions, an indirect heating boiler is installed. In addition to heating water, heating of residential premises also belongs to its functions. It can be not only a country house, as many people think. The boiler can be installed in the apartment, on the production site. The range of application is very wide.

But, the effectiveness of the installation of such a system is determined by the piping scheme, and it is not necessary for professionals to install it. Installation and strapping can be done by yourself. It is only necessary to understand the complex strapping scheme.

Connection rules

The indirect heating system is another circuit, in addition to the existing one, which produces heating of an additional container, which is called a boiler. It is supplied with the most ordinary water from the water supply, which is heated by a coil. In such a system, there is no direct interaction between the coolant and the resulting hot water. Therefore, it is called indirect.

Before proceeding with the installation, it will not be superfluous to familiarize yourself with some rules.

• The water must enter the bottom of the boiler. And the exit must be done from the top.
• The circulation of the coolant of such a system should go from top to bottom.

If you use these rules, then the system will work with maximum efficiency.

The following video clearly shows some options for piping an indirect heating boiler.

Types of strapping

Under the piping of the indirect heating boiler, they mean the connection of the pipelines of the boiler itself with the water supply. The operation of the system as a whole depends on how the installation is carried out.

This is the easiest way to tie. It is used when a large amount of water is consumed.

The boiler is connected to the main circuit and additional. The first is used to distribute heat to the batteries, the second circuit heats the water in the boiler itself. For proper separation of flows, a three-way distribution valve is connected.

The thermostat monitors the temperature of the water in the tank, and when it reaches the set value, a signal is given to the servo. And he already sends a stream of heated water to the main circuit, for heating. If the water temperature drops again, it will switch in the opposite direction and the coolant will return to the coil.

The most important point of setting is that the temperature set on the thermostat must be set higher than the temperature set in the heater! Otherwise, it will not be possible to heat the water to the mark at which it will switch to the heating circuit.

Piping with two pumps

Another piping option is with the parallel use of two pumps. One is mounted on the heating circuit, the other on hot water supply. The control of the pumps, as well as the first case, is entrusted to the thermostat. It is he who switches the operating mode.

The quality of heating at the same time remains at a high level. The main thing is that when piping with two pumps, be sure to mount check valves at the outlet of each. This is done so that there is no mixing of oncoming flows inside the coolant.

Harness with hydraulic switch

If there are many branches in the heating system, such as a multi-circuit battery system or a separate branch to a warm floor, then it makes sense to use this type of piping. To avoid difficulties with a system in which each of the circuits is equipped with its own recirculation pump, a hydraulic distributor is used.

The water gun must balance the pressure in each direction and prevent thermal shock. As for this type of strapping, difficulties are possible here. Therefore, it is better to entrust such a task as installation and subsequent adjustment of such a system to professionals.

Coolant recycling

In the event that hot water is needed as quickly as possible, then it would be more correct to use a recirculation system. Due to the fact that an annular coolant line is formed in the system. The constant movement of water through it leads to heating. That is why the waiting time for hot water is reduced to a minimum.

To ensure the continuous movement of water, a recirculation pump is installed in such a system. Such a hot water flow must be installed so that it passes through installations that constantly need heating. A heated towel rail is an example of such a device.

Connecting the boiler to a gas boiler

For the correct functioning of a boiler with a gas boiler, it contains a temperature sensor. In order for them to work together, a three-way valve is connected. The valve regulates the flow between the main circuit and the DHW circuit.

To a single gas boiler

For such a connection, a harness with two pumps is used. It is she who is able to replace the circuit with a three-way sensor. The main thing is to separate the coolant flows. In this case, it would be more correct to say about the synchronous operation of the two circuits.

To a double-circuit gas boiler

The main in this connection scheme will be two magnetic valves. The bottom line is that the boiler is used as a buffer. Cold water comes from the water supply network. The DHW inlet valve is closed. If you open it, then at first water will flow from the buffer, which is the boiler. The buffer contains heated water, the consumption of which is regulated by the capacity of the boiler and the set temperature.

Scheme using a hydrocollector

To equalize the coolant flows in systems using several circuits, there is a device called a distributor or it is also called a hydraulic manifold. It then allows you to balance different pressures in the circuits. It can be excluded, but this will cause additional difficulties associated with adding balancing valves to the circuit. And this makes it difficult to install and adjust the entire system.

Tying a solid fuel boiler with an indirect heating boiler

Connecting a water heater to a solid fuel boiler solves two problems at once:

• hot water supply;
• obtaining a way to discharge the coolant in case of an accident.

Due to the fact that such a system has a thermostatic valve on the battery, comfort is increased. But there is a danger of overheating the boiler. The same threat occurs during power outages. If a large capacity boiler is installed, this process does not pose any danger. Because the excess heat is spent on heating the water in the water tank. Accordingly, for the normal operation of this system, a boiler with natural ventilation is needed.

One of the options for tying a solid fuel boiler with a boiler, see the following video.

Common mistakes during installation

When installing or during the commissioning process, you need to try to avoid a number of errors:

• Boiler and boiler are installed far from each other. Their installation should be made not only as close as possible to each other. But, and to simplify installation, the nozzles are correctly set.
• Incorrect connection of the pipeline with the coolant.
• Illiterate installation of the circulation pump.

Competent installation, adjustment and adjustment guarantee a stable hot water supply and allow all systems and devices to work in normal mode. That will prevent wear of parts and save on premature repairs.

How to decide on the connection diagram and install the equipment correctly, the following videos will tell you.

General information about connection diagrams:

Practical tips for installation:

BKN strapping overview:

Professional review of the 80 l boiler:

In addition to installing and connecting the BKN, regular maintenance will be required. It consists in flushing the internal cavity of the tank, removing deposits and scale, replacing the magnesium anode. Maintenance of equipment does not require much effort. If the strapping is done correctly, quick repairs will not be required, but if problems arise with the equipment, we recommend contacting specialists.

The nuances of the strapping device

It is easier to do wiring and piping if the KN boiler is installed together with the boiler, pumps and other equipment involved in the assembly of the DHW system. Embedding an additional device into an already existing network is much more difficult. In any case, for the normal operation of the devices, you will have to follow a number of rules:

• choose the right place for installation - as close as possible to the boiler;
• provide a flat surface for mounting the boiler;
• to protect against thermal expansion, install a membrane accumulator (at the outlet of heated water), the volume of which is at least 1/10 of the volume of the BKN;
• equip each circuit with a ball valve - for convenient and safe maintenance of devices (for example, a three-way valve, a pump or the boiler itself);
• to protect against backflow, install check valves on the water supply pipes;
• improve water quality by inserting filters;
• correctly position the pump (or several pumps) - the motor axis must be in a horizontal position.

For safety reasons, do not attempt to mount heavy devices on plasterboard or thin wooden partitions. Concrete and brick walls are suitable. Brackets or other types of holders are fixed with brackets, anchors, dowels.

Regardless of the type of device - floor or wall - if possible, it is mounted above the level at which the boiler is installed, or at the same level. For outdoor, you can make a pedestal or a solid stand up to 1 m high

When installing, the nozzles are directed towards the boiler (even if they are masked in the back or behind a false wall). Do not use unreliable equipment, such as corrugated hoses that cannot withstand the pressure and pressure of water.

For normal operation of the storage water heater of indirect heating, the following functional devices must be included in the piping:

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A complex technical system must be equipped with pumps that supply hot sanitary water to the taps and stimulate the movement of the coolant along the heating branch, as well as along the water heating circuit in the boiler

Cold water coming from a common or autonomous water supply must be cleaned through a sump or filter system that destroys lime salts before being supplied to the boiler. Filtration will prevent the formation of mineral sediment

After the sump or water filtration system, there must be a pressure reducer. However, it is only needed if the pressure in the branch exceeds 6 bar

Before entering cold water into the boiler, a check valve is required to prevent reverse flow.

In order for the heating water to have a reserve for expansion during the period when it is not used, an expansion tank and a pressure relief valve are included in the piping

To prevent excessively hot water from entering the taps, threatening burns, a three-way mixing valve must be installed in the circuit. It will mix portions of cold water with hot water, as a result, there will be water at the required temperature for the user

In order for the heat carrier from the heating to enter the "jacket" heating the sanitary water only when it is needed, a two-way thermostat is installed. Its server is connected to the water heater temperature sensor

Circulation and delivery pumps

Mud tank for cold water treatment

Water pressure reducer in water supply

Non-return valve in front of the boiler inlet

Safety valve and diaphragm tank

Three-way mixing device

2-way thermostat for heating circuit

Additional flow heat exchanger

What to look for when choosing a BKN

One of the main parameters that should be the decisive argument when buying a boiler is its capacity. To find out the required tank capacity, we advise you to focus on the number of people in your family.

• 2 consumers - 80-100 liters.
• 3 people - 100-120 liters.
• 4 - 120-150 liters.
• 5 - 150-200 liters.

It is important to separate the concepts of "total tank capacity" and "working capacity", because the spiral pipe located inside the boiler occupies a significant area. Therefore, be sure to specify when buying how much water is actually placed in the device (this nuance should be indicated in the technical specifications)

Also, in addition to the "total" recalculation of potential consumers, it is necessary to take into account both the frequency and volumes of water use. For example, if your family likes to soak in a warm bath, and not take a quick shower, the working capacity of the tank should be appropriate - at least 120 liters.

It is advantageous to use BKN in combination with a solid fuel or single-circuit gas boiler, but if the water flow is less than 1 l / min, a double-circuit boiler will cost less, which will take up much less space than an indirect heating system

Other important parameters:

1. Power- the greater the water consumption, the higher the resource of the device should be. But at the same time, it is important that the power of the "indirect" does not exceed the capabilities of the heating system (or other external source of energy). For example, if the volume of the storage tank varies between 120-150 liters, the boiler power should be at least 23 kW, and for 160-200 liters 31-39 kW will be needed.
2. Heating time- a parameter depending on the volume of the tank and the number of turns on the coil (large or combined tanks can be equipped with several coils).
3. tank material- for long-term use, boilers made of stainless steel or medical steel are best suited.
4. thermal insulation- cheap models use foam rubber, which wears out quickly and transmits heat, so it is better to purchase a more expensive device where polyurethane was used.
5. Control- the device will be able to work in automatic mode, if necessary, turning off and starting the flow of water, control heating using a temperature sensor.

When choosing the shape and size of the tank, it is also necessary to take into account that although theoretically the boiler can be installed in any room where there is access to the heating main, its optimal location is next to the boiler. So heat transfer is most efficient.

What is a boiler

A boiler is an automated household appliance designed to heat water. It is a storage tank, which is equipped with a heating element outside or inside. The scope is quite wide, it can be installed both in a public place (sauna, office, restaurant, bar), and in a country house, in a private country house or apartment building.

The most widely used boilers with internal heating, their distinctive feature is a serpentine heat exchanger, immersed to the entire depth of the tank. The heat exchanger circulates the heating medium (water, electricity, oil, steam).

A boiler with an external heater works at the expense of thermal energy obtained as a result of burning energy carriers (wood, coal, gas).

Water heater with external heat exchanger, fired with wood

The heated water in the boiler tank is distributed in layers, the hottest is at the top. That is why the water intake for consumption is carried out from the upper part, and the cold water supply is respectively connected to the lower part.

The developers of water heaters have created the most effective heat-insulating layer. It provides long-term cooling of water in the tank. As a result, the heat loss of a modern high-quality boiler is only 3 degrees per day.

Connection diagram with three-way valve

This method is suitable for dwellings with high hot water costs. It involves the creation of two heating circuits: the main one - to move the water supplied to the heating system, and the additional one - to heat the boiler water directly. For the correct distribution of water flows along the circuits, a three-way valve is used, the operation of which is regulated by a special boiler thermostat.

After connecting the boiler, the system functions in this way: when the water in the boiler tank cools to the lower threshold temperature mark, the thermostat switches the three-way valve from the heating system circuit to the boiler circuit, and when the water in the tank receives heat and heats up to the programmed temperature, the valve switches back and resumes coolant supply to the main heating circuit.

Connection diagram with three-way valve

The thermostat plays a central role in this system - it controls the water heating temperature and thereby protects the working equipment from deformation. But in order for the thermostat to do its job correctly, it must be set correctly.

It is important to note here that if the programmed water heating temperature in the boiler tank is higher than the base temperature of the medium in the heating boiler, the water heating in the boiler will be performed on a permanent basis - the valve will not switch to the main heating circuit, since the maximum set temperature is not will be reached. All this together can provoke a malfunction of both the boiler and the boiler.

How does an indirect heating boiler work in summer

The heating tank is effective not only during the heating season. Such a design can maintain hot water not only in a separate unit, but also as the main source of hot water supply. To do this, it is necessary that the coil is heated directly from the boiler equipment. It is especially convenient to use such a scheme in private houses and cottages where solid fuel and gas boilers are installed.

After the device is started, it will fully provide the system with hot water around the perimeter. Due to the presence of a coil and a thermostat inside, the pump will constantly maintain the temperature in the system within 70 degrees Celsius.

Connected boiler to heating equipment and electric heaters

This method is possible only if there is a separate boiler equipment that can operate from natural heating sources in the form of liquefied gas, coal or firewood all year round. In case of connection to central heating, this method will not be effective.

In order to maintain a normal water temperature, it will be necessary to install heating elements inside the boiler. They will heat the water inside the tank using electricity. Many immediately equip the tanks with a coil and heating elements for electric heating. During the period of turning off the heating, it is enough to plug such a device into a socket and the water will be heated again. Thermostats work. As soon as the water reaches the desired limit, the counters will work and the heating will stop.

More about the boiler as an indirect heating device

Scheme of the device of an indirect water heater.

A double-circuit boiler always works on only one of the circuits, which is a disadvantage that remains in the scheme of a single-circuit boiler with a boiler, but the boiler still compensates for some of the disadvantages of double-circuit boilers.

So, in a double-circuit boiler, water is heated in the second circuit in a flow mode, and it takes from 30 to 60 seconds to reach the required temperature, which leads to a certain loss of water. The boiler, in conjunction with a single-circuit boiler, is a heat accumulator and, like a thermos, retains it for a long time.

Only an uninterrupted supply of gas or electricity and properly functioning primary heat sources can guarantee the normal operation of the DHW boiler. Boilers operating on solid or liquid fuels are more reliable in this regard, since the amount of stored fuel must be calculated according to the required energy for heating the house, taking into account domestic hot water.

Providing hot water after the end of the heating season using the same heat source is impractical, if only because of its inefficient use, when a maximum of 50% of its installed capacity is sufficient. For this period of time, a small-capacity wall-mounted gas boiler equipped with a heating element should be provided. In addition, unlike powerful boilers, wall-mounted gas boilers have low inertia, which is useful for quickly heating water. The required power of the heating element only for heating domestic water will be much less. You can also purchase a boiler with a heating element installed in it.

Connecting the boiler to a gas boiler

To connect an indirect heating boiler to a gas heating boiler, its design provides for a temperature sensor installed in the tank.

Connection to a double-circuit boiler

To operate the boiler in tandem with a heating unit that has a hot water circuit, a three-way valve is used. With its help, the heated coolant flow is distributed between the main heating circuit and the additional hot water circuit.

The three-way valve is controlled by signals that come from a thermostat installed in the water heater. When the water in the boiler cools below the set value, the thermostat turns on a valve that directs the flow of coolant from the heating pipeline to the hot water circuit. The thermostat switches the valve to its original state when the temperature of the water in the tank reaches above the set value. In this case, the coolant flow is directed to the heating main. In the warm season, the flow is not redirected, but the combustion mode of the boiler is controlled. When the water temperature in the boiler drops, the thermostat “ignites” the main burner of the unit through a three-way valve, and when it rises, the gas supply to the burner stops.

Connecting the boiler to the boiler using a three-way valve

This connection diagram is perfect for gas boilers equipped with a circulation pump and automation. In this case, the valve can be controlled by the boiler itself by a command received from the water heater thermostat.

In a connection scheme with a three-way valve, the water heater circuit has priority over the heating circuit. The use of this method of connecting the boiler is justified for tanks of large volume or with high water hardness, which will prevent the DHW circuit from working normally.

When setting the maximum temperature of the water in the boiler (the temperature of the thermostat operation), it should be borne in mind that it must be less than the temperature set for the boiler automation.

Connection to a single-circuit heating unit

When connecting a water heater to a single-circuit boiler, a scheme with two circulation pumps is used. This type of connection can actually replace the three-way sensor circuit. A feature of this connection is the separation of coolant flows through different pipelines using pumps. The hot water circuit also has a higher priority than the heating circuit, but this is achieved only by setting the switching algorithm. Therefore, it is more correct to speak of the parallel operation of both circuits.

The alternating switching on of centrifugal pumps is also carried out according to the signals of the thermostat installed in the tank.

To prevent mixing of coolant flows, a check valve must be installed before each pump.

Boiler installation diagram in a system with two circulation pumps

The operation according to this scheme is similar to the previous case, with the only difference being that the thermostat controls the alternating operation of two pumps. When the DHW pump is turned on, the heating pump is turned off, therefore, the heating system starts to cool down. However, the short time of water heating in the boiler does not lead to a noticeable decrease in the house temperature and can only be felt during the initial start-up.

Sometimes several heating units are used to heat houses of a large area. In this case, an additional pump is installed to ensure the operation of the water heater.

Preparing to connect the heater

Boiler volume selection

Choose a place to place the unit. It is better that you have free access to all the connecting elements of the system - it will be more convenient to maintain the equipment and carry out repairs when necessary.

An example of installing a boiler in a bathroom

If a storage heater model is chosen, make sure the wall can support its weight with water. Thin interior walls and drywall partitions will definitely not cope with this task.

An example of installing a boiler on a solid bathroom wall

Install the water heater in close proximity to the water supply pipes - this way you will save yourself from the need to lay additional infrastructure. Therefore, the ideal place to install the boiler is the bathroom.

Boiler in the bathroom

Important! The heating elements of electric boilers have a fairly high power. On average, it is about 2 kW

To avoid problems with wiring in the future, experts recommend connecting this kind of equipment directly to the switchboard, using, if possible, a copper wire with a large cross section. The closer to the shield the boiler is installed, the less wire will have to be used. Consider this moment too.

Water heater power selection scheme

Once you have chosen a location for the heater, start preparing your tools and accessories.

Boiler design

In simple terms, the boiler can be compared to a huge thermos, the water in which is heated and remains hot for a long time. It consists of the following main elements:

• oval or round inner tank;
• decorative case made of plastic, stainless or enameled steel (the internal structure of the boiler is covered with it from above);
• a protective layer of heat-insulating material (located between the inner tank and the outer casing, most often made of dense polyurethane);
• fasteners with which the boiler will be mounted on the floor or wall (located on the outer casing);
• tubular electric heater (TEN), with the help of which water is heated to the desired temperature (located at the bottom of the tank);
• a thermostat that limits the temperature to a maximum value of 75 degrees (located at the bottom near the heating element);
• pipes for supplying cold and draining hot water (mounted in the inner tank);
• protective magnesium anode;
• safety valve;
• control scheme.

Electric storage boiler device

The outer body can have a different shape: rectangular, oval or cylindrical. Models are produced in various colors and designs. On the body, in addition to fasteners, there are also controls, regulators and a thermometer, with which you can control the operation of the boiler.

Particular attention should be focused on the heating element. Heating elements use different power (this value also determines the power of the boiler)

According to the principle of heating, they are:

1. Wet type. Such a heating element is in direct contact with water, as a result of which scale forms on it, which must be removed.
2. Dry type. This heating element is much more advantageous, since it is structurally located in a metal tube through which contact with water is made. Thus, the dry-type heating element is protected from scale, as is the tube itself, covered with a glass-porcelain layer.

Boiler with dry heater

Another structural element is the safety valve. Why is it needed? When the water heater is operating normally, the valve does not play any role. But in an emergency, if, for example, the thermostat breaks down, the water in the boiler will heat up to a boil, which will lead to an increase in pressure to unacceptable values ​​and a possible rupture of the internal tank. In this case, the safety valve is activated, which is located on the cold water supply pipe. When the pressure limit is reached, it opens and the water is discharged.

The safety valve can also be used to drain the water from the boiler if repair or maintenance work is required.

An important element in the device of the water heater is the magnesium rod. The purpose of this electrode (anode) is to reduce the ion exchange between the metal components inside the boiler. In return, it gives up its particles, as a result of which the effect of washing out electrons from the structural elements of the water heater is minimized, and they are less susceptible to corrosion. The anode itself breaks down quite quickly and needs to be changed periodically (if its length decreases to 200 mm and its thickness to 10 mm).

Replacing the spent magnesium rod (anode)

Like any household appliance, the boiler has its positive and negative sides.

The main advantage of this technique is that under any external circumstances there will always be hot water in the house. For small towns and villages where there are problems with hot water supply (or it is completely absent), this is the only way out.

When choosing a water heater, it is necessary to take into account the advantages and disadvantages of each of them. For example, by installing a flow boiler, you will not have to wait until hot water is warmed up, its amount will not depend on the volume of the tank. But you will need a powerful hotel machine and a power cable to connect the device, and the power consumption will also increase significantly.

Boilers with different tank sizes

The storage boiler consumes less electricity, but produces only a certain amount of hot water. And its main drawback is that it takes up a lot of space.

When choosing a boiler, it is necessary to adhere to certain criteria.

Purpose of installation

The main criterion when buying a water heater is the purpose of its purchase:

• have a reserve in case of a shutdown of hot water supply;
• instant heating of water for washing dishes or taking a shower;
• constant supply of apartments (houses, cottages) with hot water.

External dimensions and volume

Immediately you need to decide on the location of the water heater. The equipment is large-sized, you can’t put it anywhere and hang it

When choosing external parameters, one should not forget about such an important criterion as the volume of the boiler. This value depends on the number of people living in the house.

A certain role is played by the equipment of the bathroom, that is, what is used in it for bathing - a shower or a bath. Using a shower is much more economical, with such bathing, about 15-20 liters of water are spent per person. In the bathroom for a similar procedure, you will need 50 liters.

Water consumption table

If the boiler is needed only to provide hot water for washing dishes, and nothing else (without bathing), then a 15-20 liter device will suffice. Such a water heater is usually installed in the kitchen directly under the sink.

Power

Power plays an important role when choosing a water heater. The more powerful the heating element (from 1 to 6 kW), the faster the water will heat up, but will the electrical wiring in the house withstand such a load? If it is new and capable of withstanding a load of 6 kW, then the power of the boiler can be easily chosen based on the needs and number of residents. In apartments with old electrical wiring, the maximum that you can count on is a 2.5 kW water heater.

Tank lining

In cheap boilers, the inner coating of the tank is made of enamel or glass-ceramic. In expensive models, titanium plating or stainless steel is used. When choosing, a person proceeds from his financial capabilities, but a high price, as a rule, guarantees quality and durability. In the case of household appliances, you should not save.

For boilers with an internal stainless steel tank, manufacturing companies give a long warranty period.

Tank lining (stainless steel)

What else to pay attention to?

• The degree of protection against moisture and dust of the boiler (IP) must be at least 23. In the event that the water heater is installed in a bathroom, sauna, bath, you will need a more protected model with IP 44.
• It is worth giving preference to models with a dry tubular electric heater (TEN). The lack of contact with water not only prevents the appearance of scale, but also reduces the risk of electric shock, since the heating element is placed in a sealed glass.
• When buying a boiler, be sure to pay attention to the presence of a magnesium anode in it. Safer and more comfortable in terms of operation will be models with overheating protection, on indication, and an accelerated heating function.
• When choosing a boiler for a dacha where no one lives in winter, you should give preference to models with a freezing prevention mode.
• When buying a water heater, be sure to ask about its heat-insulating layer. The recommended thickness is at least 35 mm (the thicker, the longer the temperature will be maintained). The highest quality material is polyurethane foam (much better than foam rubber).

Advantageous indicators when choosing a boiler

What are the types of boilers

There are several types of water heaters depending on the principle of operation and the main energy carriers: gas and electric, storage and flow, combined, indirect heating.

Their distribution in a given country is determined by natural resources. For example, in Russia, which has large gas reserves, gas boilers of indirect heating are still in demand. And Germany was not only ahead of other countries in the electrification of every house, but also the first to start the production of electric boilers. In any country, combined water heaters are in great demand, they allow you to use resources with maximum effect.

flowing

Instantaneous electric water heater

Structurally, a flowing water heater is a small box, inside of which there is an electric heating element. Depending on the principle of operation (non-pressure or pressure), it is installed either in the place where hot water is needed (sink in the kitchen, shower in the bathroom), or cut directly into the water pipe. In it, the amount of hot water is not limited, unlike a storage boiler. But the water temperature will depend on the power of the device itself, and on the pressure (as the pressure increases, the temperature decreases).

Instantaneous water heaters are very powerful, so before you install them, you need to tidy up the electrical wiring in the house.

There is a variant of instantaneous water heater powered by gas. These are gas water heaters known to everyone since Soviet times.

indirect heating

These water heaters do not produce heat energy on their own. Their principle of operation is based on the use of heat from the heating system. The advantage of indirect heating boilers is that there are no additional costs. The heating system of an apartment or house is working, and, as if casually (as if by a side effect), the water in the boiler is heated. A coolant from the main circuit is passed through its coil.

This method of heating water is considered the most economical.

Combined

Combined boiler

This type of boilers is recognized as the most promising. If necessary, you can switch from one heating option to another, since the combined device combines two types of heating elements. For example, water heating can occur due to an electric heating element or from the energy used by a gas boiler. That is, in winter, hot water is obtained by indirect heating, and in summer from electric energy.

Cumulative

A storage boiler is the most common option for heating water. Its difference from flow models in advance heating. There are two types of storage boilers: electric and gas (in one, the heat source is a heating element, in the second, a gas burner).

Their design and principle of operation are almost the same. The only difference is that the storage gas boiler, in addition to the gas burner installed at the bottom, also has a chimney pipe at the top. Installation of gas water heaters is associated with certain problems. First, you need a full-fledged chimney in the house. Secondly, the connection of gas-using installations is always accompanied by difficulties in paperwork.

Gas storage boiler device

Therefore, storage electric boilers are most widely used. Their characteristics, advantages and disadvantages, device and principle of operation are discussed below.

Installation secrets, or how to avoid mistakes

1. Proper installation of an indirect heating boiler involves not only installing the device in accordance with the manufacturer's recommendations, but also setting it up. Otherwise, a situation may arise in which the boiler will not switch to work with the heating system. Therefore, it is important to comply with the requirement that the boiler setting temperature will exceed the thermostat setting values.
2. During installation, it is important not to confuse the direction of the coolant supply to the boiler. Failure to comply with this requirement is fraught with a decrease in the performance of the unit and an increase in energy costs. Incorrect connection of the circulation pump leads to increased noise and reduced service life. You can learn how to choose and properly install this unit.
3. When connecting the boiler, do not skimp on the installation of valves. Ball valves installed at the inlet and outlet of water and coolant will make it possible to dismantle the device without draining the liquid from the heating system and without blocking the supply of cold water to the apartment.
4. Some novice installers do not install a check valve on the supply line, considering this part to be superfluous. This is not recommended, since the heated water will be able to freely go back to the water supply.
5. Make sure that the shut-off valve from the hot water riser is closed during boiler operation. Otherwise, the water will simply go into the general system.
6. After installing the water heater, it is imperative to check the operation of the safety valve. Remember that your safety depends on the serviceability of this part. That is why it is strictly forbidden to install a check valve instead of a safety device.
7. To prevent electric shock, the device must be grounded. In the case of using a combined indirect heating boiler, a residual current device must also be installed. In addition, it is better to connect to the mains with a separate line using additional batch switches.

Principle of operation

In addition to the fact that we examined the general principle of operation of electric boilers, we will consider their individual varieties. And let's make a reservation, this difference refers not so much to the type of electric heaters, the classification of which we have already dismantled, but more to the design features. Therefore, we will consider certain special types of electric boilers, and how they work, we will devote a small paragraph to each. Although these heaters differ from standard types and not much, in order to master the situation, you should definitely familiarize yourself with them.

Electric boilers with dry heating element

Usually TEN is located directly in the water, and its connection with the body is separated by sealing gaskets. However, there is a variety called electric boilers with dry TEN, in which the heating elements are in cavities and are isolated from contact with water. These heaters are safer (there is double protection against the penetration of life-threatening potential into water, which is still a conductor) and cheaper fuel elements can be used in them.

Another plus of such devices is the simple replacement of the heating elements themselves, no additional gaskets are required, you can simply remove the failed heating element and install a new one. Moreover, there is no difference what kind it is, such water heaters are much easier to maintain.

Double-circuit electric boiler

This device is designed for heating water, both with the help of electric current and with the help of heat supply systems. The main feature that a double-circuit electric boiler has is that, in addition to heating elements, it also contains heat exchangers for hot water supply, powered by heating. This approach makes it possible to provide housing with hot water, even during the period when boiler houses or combined heat and power plants are not working.

The advantage of this system is that heating water with electricity is always more expensive than using heat networks.
Most often, these devices are equipped with an automation system that allows you not only to switch the heating elements, but also if necessary. Moreover, it can be both a flowing electric boiler and an apparatus operating on the accumulative principle. Even due to the fact that large sizes of the device are required to accommodate two types, double-circuit boilers are more often accumulative.

In short, this is all that can be said about boilers that heat water using electricity in a small article. Although, in order to have comprehensive information about this topic, you need to constantly follow the news, both in heat engineering and in the latest developments of electrical companies. But this is a topic for a book, not an article.

Recirculation system

The boiler, which has an inlet of the recirculation line, allows instantaneous supply of hot water. At the same time, by opening the tap, it is not necessary to drain cold water from the “hot” pipeline.

This is possible due to the use of a separate loop circuit with its own circulation pump. Such a circuit is called a recirculation system. A heated towel rail can be additionally installed in this line.

Scheme of a boiler included in the recirculation system

In the piping of the boiler included in the recirculation system, the following are used:

• Non-return valve - to prevent mixing of hot and cold water flow.
• Air outlet - to prevent air from entering the system when the pump is turned on.
• Safety valve - serves for emergency pressure relief.
• Expansion tank - compensates for the thermal expansion of the coolant when the valves are closed.

The pressure in the expansion tank must not exceed the opening pressure of the safety valve.

Schemes and rules for connecting BKN

The connection diagram and installation features of an indirect heating boiler depend on the class of the device and the heating system in the house. It is necessary to choose the right installation site, focusing on the location of the boiler, the tie-in of the pumps and the existing wiring. Let's try to figure out what needs to be considered when installing heating equipment.

#1: Three way valve tying method

This is one of the most popular schemes, since when it is used, the heating system and the BKN are connected in parallel, equipped with shutoff valves. The boiler must be installed near the boiler, the circulation pump should be connected to the supply, then the three-way valve. This scheme is successfully used if several heating devices are used, for example, two different boilers.

A three-way valve is a kind of switch that is controlled by a thermal relay. When the temperature drops, the automation is activated, and the coolant flow from the heating circuit is redirected to the BKN (+)

In fact, this is a priority system that provides rapid heating of water in the boiler when the radiators are completely turned off for a while. As soon as the temperature rises to the set value, the three-way valve is activated again and the coolant returns to the previous channel - to the heating system. This strapping method is useful for those who use the boiler in constant mode.

#2: Option with two circulation pumps

If the boiler is rarely used (for example, seasonally or on weekends) or there is a need for water whose temperature is lower than in the heating system, a scheme with two circulation pumps is used. The first is installed on the supply pipe, immediately before the BKN, the second - on the heating circuit.

The circulation pump is powered by a thermal relay, so it starts to operate only when the temperature drops below the required one. The acceleration of heating occurs together with the inclusion of forced circulation (+)

There is no three-way valve in this scheme; the piping is equipped with simple connecting tees.

#3: Hydraulic switch piping

This connection is used for volumetric boilers (200 liters or more) and branched heating systems with many additional circuits. An example is the heating system in a two-story house, where, in addition to a multi-circuit radiator network, underfloor heating is used.

A hydraulic distributor (hydraulic arrow) is necessary to simplify the heating system layout and avoid installing recirculation pumps on each heating branch (+)

The equipment of the hydraulic arrow avoids thermal shock, since the water pressure in each circuit will be the same. It is rather difficult to make a strapping according to this scheme on your own, so it is better to turn to professional installers.

#4: Using coolant recirculation

Recirculation is useful when there is a circuit that needs a constant supply of hot water - for example, a heated towel rail. If it is connected to the heating system, the coolant will constantly circulate, and the dryer will function and at the same time serve as a heating device.

The use of recirculation has one big advantage - no need to wait for the water to heat up to the desired temperature, it will always be hot (+)

But this scheme also has disadvantages. The main one is an increase in fuel costs, because constant heating of the water cooled in the circuit is required. The second disadvantage is the mixing of water in the boiler. Usually hot water is in the upper part, and from there it goes to the points of draw-off, here it is mixed with cold water, as a result of which the outlet temperature is slightly lower.

There are models of boilers with built-in recirculation, that is, with ready-made pipes for connecting a heated towel rail. But it’s cheaper to buy a regular tank by using tees to connect.

#5: System for working with a non-volatile boiler

A distinctive feature of this scheme is the installation of a boiler at a higher level than the boiler and heaters. Preference is given to wall models that can be hung at a height of 1 m above the floor.

Floor models specifically within this scheme are inferior to wall speed and heating quality. The water temperature is much lower (approximately as in the return pipeline), therefore, the supply of hot water is less (+)

A non-volatile type of heating is based on the application of the laws of gravity, therefore, the coolant will circulate even when the electricity is turned off. In normal mode, you can connect circulation pumps.

Working mechanism

It makes sense to consider separately the principle of operation of an electric boiler and a gas water heater. The heating mechanism has common features, but the type of energy carrier affects some features. Gas units operate according to the following scheme:

• Fuel is supplied to the burner.
• The piezoelectric igniter provides ignition of the gas mixture.
• The desired heating temperature is set using the regulator.
• The burner heats the water in the tank.
• When the required temperature is reached, the burner switches off automatically.
• When the liquid in the tank is cooled, including due to water intake and fresh tap water, the automation switches on the burner on its own.

Electric boilers work according to a similar algorithm. Instead of supplying gas, the heating element is connected to the electrical network. The temperature of the liquid in the tank is recorded using a thermocouple. If the temperature drops by the set value, the power supply to the heater is automatically switched on. If the tank is well insulated, water can retain its temperature for a long time, which provides significant savings.

What is an indirect heating boiler and what are they

A water heater or an indirect exchange boiler is a tank with water in which a heat exchanger is located (a coil or, according to the type of water jacket, a cylinder in a cylinder). The heat exchanger is connected to a heating boiler or to any other system in which hot water or other coolant circulates.

Heating is simple: hot water from the boiler passes through the heat exchanger, it heats the walls of the heat exchanger, and they, in turn, transfer heat to the water in the tank. Since the heating does not occur directly, then such a water heater is called "indirect heating". The heated water is used for household needs as needed.

Indirect heating boiler device

One of the important details in this design is the magnesium anode. It reduces the intensity of corrosion processes - the tank lasts longer.

Kinds

There are two types of indirect heating boilers: with built-in control and without. Indirect heating boilers with built-in control are connected to a heating system powered by boilers without control. They have a built-in temperature sensor, their own control that turns on / off the supply of hot water to the coil. When connecting this type of equipment, all that is needed is to connect the heating supply and return to the corresponding inputs, connect the cold water supply and connect the hot water distribution comb to the upper outlet. That's all, you can fill the tank and start heating it.

Conventional indirect heating boilers work mainly with automated boilers. During installation, it is necessary to install a temperature sensor in a certain place (there is a hole in the body) and connect it to a certain boiler inlet. Next, they make the piping of the indirect heating boiler in accordance with one of the schemes. You can also connect them to non-volatile boilers, but this requires special schemes (see below).

What you need to remember is that the water in the indirect heating boiler can be heated just below the temperature of the coolant circulating in the coil. So if your boiler works in low-temperature mode and produces, say, + 40 ° C, then the maximum temperature of the water in the tank will be just that. You can't heat it up anymore. To get around this limitation, there are combined water heaters. They have a coil and a built-in heating element. The main heating in this case is due to the coil (indirect heating), and the heating element only brings the temperature to the set one. Also, such systems are good in tandem with solid fuel boilers - the water will be warm even when the fuel has burned out.

What else can be said about the design features? Several heat exchangers are installed in large-volume indirect tanks - this reduces the time for heating water. To reduce the time of heating water and for slower cooling of the tank, it is better to choose models with thermal insulation.

Which boilers can be connected to

Boilers of indirect heating can work with any source of hot water. Any hot water boiler is suitable - solid fuel - on wood, coal, briquettes, pellets. It can be connected to any type of gas boiler, electric or oil-fired.

Scheme of connection to a gas boiler with a special outlet for an indirect heating boiler

It’s just that, as already mentioned above, there are models with their own control, and then installing and tying them is a simpler task. If the model is simple, it is necessary to think over a system for controlling the temperature and switching the boiler from heating radiators to heating hot water.

Tank shapes and installation methods

The indirect heating boiler can be installed on the floor, it can be hung on the wall. Wall-mounted options have a capacity of no more than 200 liters, and floor options can hold up to 1500 liters. In both cases, there are horizontal and vertical models. When installing the wall-mounted version, the mount is standard - brackets that are mounted on dowels of a suitable type.

If we talk about the shape, then most often these devices are made in the form of a cylinder. In almost all models, all working outputs (pipes for connection) are brought out at the back. It is easier to connect, and the appearance is better. On the front of the panel there are places for installing a temperature sensor or a thermal relay, in some models it is possible to install a heating element - for additional heating of water in case of a lack of heating power.

According to the type of installation, they are wall-mounted and floor-mounted, the capacity is from 50 liters to 1500 liters

When installing the system, it is worth remembering that the system will work effectively only if the boiler capacity is sufficient.

Types of double-circuit gas boilers with a built-in boiler are they needed

Boilers are used together with single and double-circuit gas boilers. In the second case, the unit itself works only for heating. Allocate freestanding and built-in boilers.

The former are often purchased separately, have a large capacity, suitable for single- and double-circuit devices of open and closed type. Require complex connections.

Built-in tanks - part of turnkey solutions on the basis of double-circuit boilers. They are compact due to their small volume, they are equipped with advanced automation from the factory, they can be easily connected.

Important! The volume of a stand-alone boiler is selected in proportion to the power of the boiler. If the tank is too large, then the water in it will not warm up to the required 60 ° C according to sanitary standards.

This is fraught with the appearance of legionella colonies that are dangerous to health.

Modern devices with built-in storage devices have the anti-legionella function: the boiler automatically warms up from time to time up to 65 °C for 30 minutes thereby killing harmful bacteria.

Double-circuit gas boilers with boilers differ in location, type of storage and its capacity.

By location: floor non-volatile and wall

Floor stand-alone boilers are large in size and high power. The mass of the heating device without liquid reaches 100 kg. Equipped with built-in boilers up to 120 l, external hinged or floor - 50–500 l.

Photo 1. Floor double-circuit gas boiler with an indirect heating boiler, installed in a special room.

Often require placement in a specially equipped boiler room. They heat up and supply water quickly, but sensitive to power surges. They create problems when connecting the recirculation system.

Wall-mounted equipment is smaller and weaker than outdoor equipment. It does not require the arrangement of a separate room, it is allowed for installation in bathrooms and kitchens. Usually equipped with built-in tanks of indirect heating with a capacity of 10–60 l with constant heating of the liquid by the secondary DHW circuit.

Less often they are connected to free-standing boilers of the same volume. Their heat exchangers have a small internal section, which is why the devices afraid of scale and are very sensitive to water quality.

By type of boiler with electric heater

Boiler direct heating equipped with its own heating element, independently raising and maintaining the temperature of the water. Often this is a tubular electric heater (TEN), powered by mains or gas. The installation of the second option also requires permission from the supervisory authorities.

The DHW system can be based exclusively on a direct heating storage tank, bypassing the connection to the boiler.

Indirect heating boilers do not have their own active heating element. Placed in a water tank coil, passing through itself a coolant preheated in another heater. Installed with gas equipment with a capacity from 25 kW, A network connection is required for the automation to work.

Photo 2. A double-circuit gas boiler with a combined boiler heats the water in the tank due to the operation of the coil.

Combined boilers have an indirect coil and a heating element that directly heats the water in the tank. work item maintains the temperature at the required level, but most of the heating is provided by the coil.

Reference! Combined drives are suitable for low power single and dual circuit equipment. Reduce electricity consumption during the heating season, providing the necessary heating of water during the entire period of operation.

Factors on which the heating rate depends

In any storage water heaters operating using electric energy, the process of heating water is carried out by one or two heating elements, which may have different power ratings.

The complete set of small volume tanks (no more than 15 l) is represented, as a rule, by one heating element with a power of 1.0 kW. In storage electric water heaters with a useful volume of 50 liters, a heating element of 1.5 kW is most often installed. High-power water-heating structures with a tank of 100 liters are equipped with a heating element with a power of 2.0-2.5 kW.

This version of the heating element is called "wet".

The water heats up when it comes into contact with the heating element.

The water heating time directly depends on such factors as the boiler power, the surface area of ​​the heating element, and the heat transfer coefficient.

Therefore, it is extremely important to purchase modern storage water heating equipment with a sufficient amount of high-quality and durable heat-insulating material.

4 boiler piping schemes

So far, mankind has come up with only 4 main ways to install an indirect heating boiler. Each of the methods has its own characteristics, as well as recommendations for use. Let's consider them in more detail.

Three-way valve and servo

This method is used when tying a single-circuit boiler and a boiler. Suitable for both wall and floor appliances.

The servo in this circuit serves just to control the operation of the valve. This control takes place using the thermal relay of the boiler itself. It should be noted right away that in order to use this particular scheme, it is necessary to circulation pump and expansion tank. The pump is used to move the cooled water from the DHW line to the water heater. That is why hot water will flow immediately, it is worth turning the faucet valve.

The expansion tank for the water heater cannot be used for the heating system. It's all about the temperature difference of the working fluid. The tank can only “hold” water up to 70˚C, while the heating system can use technical fluid, whose temperature can reach 120˚C.

The essence of the method: the leadership in the pair "boiler - water heater" clearly belongs to the boiler. So the thermostat controls the valve. When a signal comes from the thermostat, the three-way valve redirects the fluid flows either to the heating system or to the hot water supply.

For example, if the liquid in the boiler has cooled down, then the valve “sends” the liquid into the water heater coil to heat it up. After completing this task, the coolant is redirected back to the heating system.

If your area has very “hard” water, then we recommend using a single-circuit boiler + boiler with a valve, rather than a double-circuit boiler. All internal components and parts of the latter break very quickly with constant contact with hard water.

Remember to set the thermostat correctly! If the highest water temperature in the water heater tank exceeds the temperature of the water in the heating circuit, then only the water in the water heater will be heated. The turn will not reach the heating system, since the maximum level of water temperature in the boiler will never be reached.

Scheme of an indirect heating boiler with a three-way valve

System of 2 circulation pumps

As you probably already understood from the name, a separate pump is responsible for the movement of fluid in each circuit. By the way, the boiler pump is mounted in front of the boiler pump, so a three-way valve is not needed.

The boiler and water heater are mounted in parallel, and their interaction will occur due to the pump. By the way, the last word in the “boiler - water heater” pair again remains with the DHW circuit.

A non-return valve is required after each pump. This helps to avoid "contact" between two threads.

The essence of the method: both circuits cannot work together. When the DHW line is activated, the heating system is switched off. But this is not scary: the water reaches the desired temperature very quickly (20-40 minutes). During this period of time, the temperature of the batteries will not drop to a critical level.

Hydraulic arrow way

The hydraulic arrow is the distribution of water flows in the heating system.

This method of strapping is relevant if a large area (from 80 sq.m.) is to be heated, when the heating system is highly branched, that is, it consists of several “independent” circuits (DHW, underfloor heating, batteries, etc.). The arrow allows you to equalize the pressure and speed of water in all circuits.

Recirculation method in the DHW system

Connection of heating boilers and indirect heating boilers in the house

This method is real if the manufacturer has provided a 3rd inlet in the boiler, through which water will be recirculated. This is necessary to increase the rate of hot water supply to the water intake point. Roughly speaking: they opened the tap and hot water immediately flowed, as we said before.

Advantage of the method: high water savings, since you will not need to wait until all the cold water is drained from the pipe until the turn reaches the already hot one.

What will be needed to implement this system?

• check valve- thanks to him, hot water will not enter the cold water system if the pressure in the boiler is high.
• Safety valve n - will protect the water heater from damage due to pressure surges.
• Expansion tank- stabilizes the pressure in the hot water supply with closed valves.
• Automatic air vent– removes air that has entered the system.

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Various boiler piping schemes

There are several main ways to tie a device, which are:

With two circulation pumps

Both pumps are designed for parallel operation. One of them is installed on the heating pipe, the second - on the warm water supply. Their switching on and off is carried out due to the operation of thermal relays.

A feature of this connection is the need to install check valves. They are mounted after pumping devices. This is necessary to prevent mixing of flows in the coolant.

In detail, the correct location of all elements of such a strapping can be considered in the diagram:

3-way valve with servo

A servo drive is a system element responsible for controlling the operation of a three-way valve. In the case of the described equipment, such a device is a thermal relay, which can be an integral component of the main heating device or installed additionally.

The system is set up like this:

• 1. There are two circuits:
  • boiler room
  • heating
• 2. When the temperature in the hot water system drops, the thermostat gives a signal to the valve.
• 3. The valve switches the movement of the coolant towards the indirect heating boiler.
• 4. When the desired thermal indicator is reached, the thermostat signals this to the valve.
• 5. The flow to the heating circuit is switched over.

The diagram shows the piping method with a 3-way valve:

Hydraulic arrow method

This option is used when there are multiple circuits. Outlines may include:

• indirect heating boiler;
• warm floor;
• main radiator heating.

If you do not install a hydraulic arrow with such an arrangement of the system, then it will be necessary, instead of it, to install balancing valves. Their installation will be necessary due to the pressure difference in different circuits.

The figure shows a plan for such a strapping:

Recirculation method in the DHW system

This method accelerates the supply of heated water to the consumer.
To provide this type of piping, a third input must be present in the boiler to connect recirculation components to it.
The carrier that pumps the pump goes through several cycles along the line, thereby providing more efficient heating of the water inside the boiler.

A plan for such an arrangement is presented below: