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Combined indirect heating boiler tank in tank. Indirect heating boiler - what is it? Connection on the water supply side

Indirectly exploiting opportunities heating system, is becoming increasingly popular today among residents country houses and private sector cottages. Indirect heating of water for a domestic hot water system is the most energy-efficient, economical and intelligent way to heat water of all available methods.

Boiler indirect heating, as opposed to direct heating, which heats water using gas or electricity, provides housing with hot water at a minimal cost. A heater of this type is a tank in the form of a rectangle, cube or barrel made of a metal sheet with heat-saving insulating material and resembles a huge thermos.

An indirect heating boiler is usually installed next to the boiler in the boiler room; there are branded kits where the installation is thought out directly to the boiler equipment.

What is an indirect heating boiler

What is it for?, the typical average person asks first of all. Owners of country houses rightly believe that it is much easier to buy a double-circuit boiler. One circuit will be used to heat the household using a heating system. The second circuit will prepare hot water for DHW, thus immediately solving two issues with one purchase.

Yes, such reasoning is fair, but up to a certain point. Firstly, the double-circuit boiler instantly switches to hot water preparation mode as soon as you open the tap. At this time, the boiler completely stops taking care of your heating system, leaving it to the mercy of fate. Simply, the boiler directs all its power to DHW heating, blocking heating of the heating heat exchanger.

Secondly, as a rule, a double-circuit boiler does not have the full functionality of a gas water heater; its power is hardly enough for one water collection point. It turns out that if a family returned from a ski trip and the household decided to take a shower, then the heating system will be turned off for at least a couple of hours.

In addition, the rest of the family will have to wait patiently for all participants and not open the tap in the kitchen if they do not want to hear flattering words addressed to them. Thus, only at first glance an indirect heating boiler looks like a waste of money. In fact, this is a necessity to ensure comfortable stay. An acceptable compromise would be to buy an indirect heating boiler with a capacity of 200 liters.

Schematic diagram of an indirect heating boiler

Installed inside heat exchanger - the heart of the structure, is most often made ofbrass or carbon steel, coolant circulates through it from the heating boiler. The heat exchanger has the shape of a spiral, which allows you to quickly and efficiently heat the liquid in the tank.

Through the hot water outlet and cold water inlet, the device is connected to the main water supply system. It turns out that the design of an indirect heating boiler is more than simple, and it is not even clear why the simplest invention was not used by humanity for so long.

By spending just three and a half minutes watching the video review, you will understand the principle of operation of an indirect heating boiler, especially since the video series is easier to understand:

Indirect heating has the following advantages in use:

• The main advantage is that an indirect heating boiler does not require financial costs for operation. It does not at all burden the electrical wiring with additional load during the peak heating period, because the described system does not consume electricity;

• Due to the closed circuit, the water constantly circulates through the boiler and is in a hot state; after opening the tap, the consumer immediately receives a hot stream without draining the cold sludge;

• The recirculation process not only keeps the water hot, but also protects the hot water system from infection by pathogenic microorganisms - Legionella. Supported heat, interferes with their development.

• Running water is excluded from interaction with inner surface heat exchanger tubes, scale and salts are not deposited in it, which makes it possible long-term operation boiler systems;

• Large reserves hot water and increased power modern designs allow the liquid to heat up much faster than traditional storage tanks. The volume of reserves easily makes it possible to connect an indirect heating boiler to two or more points consuming hot water.

• The coolant coil and the auxiliary heating element are protected from corrosion by a special anode. In fact, the anode takes on the entire corrosion load, extending the service life of the heating elements.

This device also has some disadvantages:

• depending on connected heat sources;
• V summer period, in the absence of heating, it is necessary to connect to electricity, which is why it is equipped with electric heaters.

Essentially, an indirect water heating system uses thermal energy generated by a solid fuel or gas boiler. The combination of a heat-generating device and an indirect heating boiler forces the boiler to do double work. The advantage is especially felt in winter - it turns out that the water is heated for free, due to the fact that the heating system is working one way or another.

In winter, the cost of heating water can account for up to one third of all energy bills. Connecting an indirect boiler system to a gas or pellet boiler effectively contributes to saving our finances.

Advantages and disadvantages of an indirect heating boiler

The positive factors of using such a boiler include:

• Indirect water heating does not create additional load on the electrical wiring, especially during the heating season, since it is connected to centralized heating and has practically nothing to do with electricity;
• with proper connection and configuration, the boiler is able to show a high performance coefficient with an acceptable cost comparison;
• the heater located inside as well as the coolant do not come into contact with the inlet water, thereby ensuring the duration of operation and safety of the unit;
• It is always possible to connect an indirect heating boiler to other heat sources, as well as simultaneously use several devices, creating a cascade.

The tank and emergency heating element are protected from corrosion by an anode made of magnesium alloy. To avoid the maximum permissible pressure, a thermostat and a safety valve are installed in the boiler. The tank body can be of any design to suit a variety of interiors.

Along with the undeniable advantages of this system, there are also disadvantages:

• if it is necessary to re-equip an existing system, you need to be prepared for the costs;
• The price of an indirect heating boiler is very high; the initial costs of purchase and installation will require significant financial resources. So, the price will always be higher than the cost or;
• after installation and first start-up, heating the first 100 or more liters of water will last up to two hours, which may negatively affect the heating of the house during this period;
• buying a boiler is only half the battle, a capacity of 100 - 200 liters has large dimensions that will have to be taken into account, your boiler room must provide free space.

How to choose an indirect heating boiler

The main difference between a boiler and a boiler is the tank capacity. For the right choice and to avoid excessive costs, when purchasing a boiler, you need to know how much water will be required to meet the demand of the family unit. The average indicators are presented by the following calculations: personal hygiene, per day - up to 15 liters; the washing up kitchen utensils- up to 25 liters per day; shower - up to 100 liters per day; bathroom - up to 200 liters.

It is generally accepted that one person consumes about one hundred liters of hot water, but this, of course, is a convention; actual consumption depends on the person himself and his habits. Some people visit the shower twice a day, others spend one day a week taking a bath. We can certainly say that a larger heater volume will have a higher cost.

The second important factor influencing the cost of the boiler is the materials from which it is made, in particular its internal parts. It is recommended to choose a unit with a brass coil, which gives more efficient heating compared to steel. Brass is also convenient because it is much easier to remove scale from it than from steel.

The level of corrosion protection should also be taken into account. In inexpensive models, the surface of the tanks is covered with an enamel layer or glass ceramics. In higher quality devices, instead of an internal coating, stainless steel is used in the production of the tank.

A good boiler must be provided with a thermal insulation layer. This material is used either basalt wool, or gas-filled plastic- polyurethane foam. If the thermal insulation of the boiler is foam rubber, it is better to ignore this model.

Correct connection of an indirect heating boiler

The first step is to correctly select the location of the device. It is necessary to take into account, at the place where the boiler is installed, quick and easy accessibility to important connecting links of the system - this will allow for routine maintenance renovation work equipment and carry out maintenance.

Mounted models of an indirect heating boiler will require a strong brick load-bearing wall at the mounting location. Walls made of plasterboard or light interior partitions cannot provide the required rigidity and cannot be fully used in installation work

The distance from the tank fastenings to the ceiling should be 15-20 cm. The fasteners are anchor-type spacer bolts, and their length and diameter are selected based on the wall material and the volume of the boiler.

The approximate load for tearing out a container of up to 100 liters is from 25 to 25 kilograms, when mounted on concrete wall a bolt will suffice 10 mm thick in diameter and 100 mm long. For the same parameters, but taking into account the brick-cinder block wall, you need a bolt with a diameter of 12 mm and a length of 120 mm.

After installing the heater to the wall, it must be connected, for this:

• two separate shut-off valves are installed on it;
• a fum tape is wound and a discharge valve is attached to the cold water inlet line;
• connection to the water supply system is made using a flexible hose;
• After all connection operations, you can supply cold water to the water heating and at the same time turn off the hot water tap - this will allow any possible air to bleed out.

Connecting an indirect heating boiler

Can be done using like hydraulic system, and electric. The most effective is considered to be a scheme in which the connection occurs on 2 pumps, i.e. a hydraulic scheme, where one of the pumps functions as a room heater, and the second is used for indirect heating of the boiler itself. The electrical connection is made via a relay switching system.

When an indirect heating boiler is connected through two pumps, the heat-carrying flows move in different directions due to the operation of recirculation (recirculation) pumps.

The hot water supply line coming from the coolant and the water heater is simultaneously connected to the circulation pumps, and the operating mode of the pumps is controlled by the heater temperature sensor.

Direct-acting fittings in the form of a check valve must be installed behind the pumps in sequence, for autonomy and independent operation of the pumps from each other.

Connection to pipes made of various materials

The insertion of the boiler may differ slightly, depending on what material the water pipe is made of.

Polypropylene pipe

Pipes not sewn into the wall will not create connection problems. The work will consist of cutting the water supply pipe in the required location and soldering tees into the holes, from which tubes will go to the boiler. The taps are connected using ordinary couplings. If the pipes are walled up, the algorithm of actions will change slightly:

• pipes should be opened;
• a cut-in occurs;
• pipes are diverted;
• pipes are sewn into the wall.

Metal-plastic pipes

Since there is no technology to install such pipes using a hidden method, insertion will not be a problem. The pipes are cut, tees are attached to them, and water supply pipes are connected to the heater.

Steel pipes

Connecting to steel pipes is a complex matter. In this case, it is rational to use the mixer pipes through which the tank will be connected. Tees are put on the pipes, by connecting them, the water heater and mixer are connected to one pipe.

Frequent mistakes when connecting an indirect heating boiler

A common mistake is not appropriate place placement of the boiler. It should be installed as close as possible to the heating boiler or central heating outlet - this will help save on laying additional pipes and other accompanying infrastructure.

The bathroom is almost ideal for this; the only catch is its small dimensions:

Another “popular” mistake is incorrect connection of the cold water inlet. Connecting the thermal energy substance (thermal body) in a sequential order of input and output must ensure correct and efficient operation of the boiler.

The optimal and effective option for heating and heat supply would be to enter the coolant into the water heater from above, and exit, accordingly, from below.

Incorrect connection of the circulation pump can lead to a lot of adverse consequences, namely:

• different from horizontal arrangement the motor axis can lead to rapid wear of the bearings;
• An important factor is keeping the pump clean and free from debris. Mesh filters should be checked regularly.

Cost of equipment

Potential buyers, faced with the choice of an indirect heating boiler, solve the problem of finding an acceptable price for equipment with optimal functions. The cost of equipment presented in stores varies greatly depending on the model. Here are just a few factors influencing pricing:

• Manufacturing company. European analogues, due to the influence of the high cost of EURO, will cost more than the same Korean ones. However, the quality level of the leading brands in the Eurozone: , ACV, Viessmann, Buderus, Vaillant, Protherm, Drazice, Gorenje, always remains at its best, which makes the products in demand in the domestic market.
• Materials present in the product and the quality indicator of the tank.
• Accessories high quality and not so good. Expensive models are equipped with tanks made of brass or stainless alloy. Hull cladding made of such material also leads to an increase in price.
• Constructive solution. The “tank in tank” module leads to higher costs compared to the traditional design of an indirect heating boiler.
• Dimensional parameters of the device. Of course, a more spacious tank is offered at an increased cost.
• Functionality. Equipping an inlet for a recirculation system requires additional costs in the production process. As you might guess, the seller will include everything in the final price.

At the beginning of 2018, the price for an indirect heating boiler design foreign production, with a volume of 100 liters is formed in the region of 50-90 thousand rubles. The cost of a similar boiler with a volume of 300 liters increases to 100 thousand rubles, and for a device with a capacity of 1000 liters, you will have to pay 350-450 thousand rubles.

Conclusion

Based on numerous positive reviews from boiler owners indirect heating, you can see that the system is quite popular and in demand. When purchasing a particular model, almost all the information can be found on the Internet, where you can also consult online stores specializing in such equipment.

For private homes, such designs will be an indispensable help in saving money, and you can forget about the lack of hot water.

This question is often asked by owners of private houses. Many people rightly believe that if they already have installed system heating system, which allows you to supply the house not only with heating, but also with hot water for household needs, then why spend money and install an indirect heating boiler? At first glance, the boiler design really looks like an unnecessary waste of money. But that's not true.

The indirect heating boiler has a very low coefficient heat loss

What is an indirect heating boiler and why is it needed?

An indirect heating boiler is a water heater that allows you to provide an uninterrupted supply of hot water to all households at the same time.

In addition, its design does not imply the presence of its own heat source. External heat sources are used as a heat carrier for an indirect heating boiler. They can be a heating boiler, central heating, etc.

So, why do you need an indirect water heating boiler? Let's take as an example a situation where the lady of the house decided to wash the dishes, and the owner of the house, meanwhile, decided to take a shower. In this case, both will face either a lack of hot water or a sharp drop in water temperature, which is also unpleasant. The design of this water heater will allow you to avoid such situations, since it will be able to compensate for the resulting shortage of hot water.

How does an indirect heating boiler work?

Externally, an indirect heating boiler looks like a large tank with a cylindrical shape. And the boiler design itself consists of the following parts:

• boiler body;
• insulation;
• tank made of stainless steel;
• thermometer;
• heat exchanger;
• magnesium anode.

Due to the presence of a layer of insulation between the tank and the body of the boiler itself, the heat loss coefficient is 3-4ºC per day. The thermometer allows you to control the set temperature of the water in the tank. The heat exchanger is a spiral-shaped steel or brass tube, which is located inside the boiler itself. Very often this tube has a complex shape and is located closer to the bottom of the boiler. Manufacturers claim that it is thanks to this fact that it is possible to achieve uniform heating of water throughout the entire container. The magnesium anode is designed to protect the tank from galvanic corrosion. Almost all electrochemical reactions will affect the magnesium anode without affecting other parts of the water heater. Over time, this part of the water heater will have to be replaced as it is subject to constant wear and tear.

Almost all new models of modern boilers have an alternative heat source. Such devices are also called combined. In the summer, when the heating season is over, boilers use either electricity or gas to heat water. There are also models on the market that can heat water using sunlight.

Operating principle of the device

An indirect heating boiler is simple in design, and the principle of its operation will be clear to anyone. Inside a large tank there is a hollow spiral-shaped tube, most often called a coil. The coolant continuously circulates in the tube. Constant circulation is ensured by a pump specially installed for this purpose, which, in turn, is equipped with an automatic control system. As soon as the water temperature reaches the set parameter, the pump turns off. Since the source of the coolant is a working heating system, when the water in the boiler is heated, a slight decrease in the temperature of the heating elements is possible. However, the water in the tank heats up quite quickly, so you can only notice a decrease in temperature for a short time using a thermometer.

Once the water in the tank reaches the desired temperature, it will remain that way for a long time. Modern technologies help to significantly reduce heat loss in the tank. insulating materials. Excellent as thermal insulation for boilers expanded polystyrene is suitable or polyurethane foam.

Each boiler has two pipes for inlet and outlet, and they perform different tasks. The inlet pipe is connected to the heating boiler, where coolant enters the coil through it, thereby heating the water in the tank. And the outlet pipe supplies already heated water directly to the point of its supply.

Before you decide to buy a boiler, be sure to check the power of your heating system. After all, if you purchase a boiler with a large volume, there is a possibility that the heating system in your home simply will not cope with the task. Or heating will occur very slowly, and during this period the temperature heating devices will decrease sharply, which will have an extremely negative impact on the comfort of people living in the house. You will also need to choose in advance what type of boiler you want to purchase: floor-mounted or wall-mounted. If you have a wall-mounted water heating system, then it is best to purchase a wall-mounted boiler. And vice versa. Experts advise purchasing a heating system and an indirect heating boiler from the same manufacturer. In this case, installation and installation will be easy and quick. And the results of their work will be effective and productive.

Advantages and disadvantages of the system

The main and main advantages of indirect heating boilers, in contrast to flow-type heaters, are:

1. Ability to heat water in large quantities.
2. Compensation for emerging hot water shortages during peak load periods. For example, when the hostess decided to wash the dishes and the owner decided to take a shower. Thanks to the boiler, several people in the house will be able to use hot water at once without causing discomfort to other users.
3. The cost of water heated by an indirect heating boiler is extremely low. After all, no additional energy was spent for its production. The indirect heat source completely satisfied the need for heating water. IN winter period Over time, the use of a boiler becomes extremely important due to the high savings in energy spent on heating and heating.
4. Compared to a flow-type water heater, the use of an indirect heating boiler makes it possible to supply hot water in several directions at once.
5. Possibility to use alternative heat sources (gas, electricity, sunlight, etc.).

The disadvantages of indirect heating boilers include the following:

1. High cost of equipment. Considering the fact that to install an indirect heating boiler it is necessary to first install a heating boiler, installation of the first places a heavy financial burden on the owners of a private house.
2. It will take several hours to heat water in a 100 liter container. During this period of time, the heating temperature in all residential areas will be reduced.
3. The whole structure takes up quite a lot of space. Typically, a heating boiler and an indirect heating boiler are installed in close proximity to each other. And since the dimensions of the equipment are rather large, sometimes a whole small room in the economic zone.

How to choose the right boiler?

The main criterion that you should follow when choosing a boiler is its capacity. In order to understand what the optimal weight of your water heater should be, you can use the average statistical indicators, and then multiply them by the number of people living in the house and round the resulting figure up.

So, statistics say that a person spends hot water per day on:

• washing – 6-16 l;
• washing dishes – 20-25 l;
• shower – 60-85 l;
• taking a bath – 160-180 l.

For example, in order to heat water to the required temperature in an indirect heating boiler with a capacity of 20 liters, it will take about 40 minutes, and for a 200-liter boiler it will take about 6 hours.

Once you have decided on the required volume of the boiler, be sure to check what material the coil is made of. In inexpensive boilers, the coil is made of steel and welded to the tank. And in models of a higher price category, the coil is removable and made of brass. Of course, a removable coil is more practical, since over time you can easily remove it and clean it from the scale accumulated in it.

Also, inexpensive models have quality protective coating a layer of glass ceramics or enamel. However, such a coating is not entirely reliable, because constant temperature changes will occur inside the tank, which over time will lead to microcracks and will no longer protect the metal from corrosion. Therefore, when buying a boiler, choose a tank that is made of stainless steel; such a boiler will cost you more, but will also last much longer.

The next thing you will need to pay attention to is the insulation material. Some models use foam rubber as insulation; this material is extremely unreliable and impractical. Polyurethane is best suited for these purposes. It is with such insulation that heat loss from the tank is practically eliminated, which means that excess energy is not wasted on reheating the water.

Hot water in taps has long ceased to be a luxury. Today this is one of the mandatory requirements of normal life. One of the possibilities for organizing hot water supply for a private home is the installation and connection of an indirect heating boiler.

What is an indirect heating boiler and what are they?

A water heater or indirect exchange boiler is a tank of water in which a heat exchanger is located (a coil or, like a water jacket, a cylinder within 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 occurs simply: 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 container. Since heating does not occur directly, such a water heater is called “indirect heating”. The heated water is used for household needs as needed.

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

Kinds

There are two types of indirect heating boilers: with and without built-in controls. 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 you need to do is connect the heating supply and return to the appropriate 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 housing) and connect it to a certain boiler input. Next, they wire the indirect heating boiler in accordance with one of the diagrams. You can also connect them to non-volatile boilers, but this requires special circuits (available below).

What you need to remember is that the water in an indirect heating boiler can be heated slightly below the temperature of the coolant circulating in the coil. So if your boiler operates in low-temperature mode and produces, say, +40°C, then the maximum temperature of the water in the tank will be exactly this. You won't be able to heat it up anymore. To get around this limitation, there are combination 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 paired 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? In large-volume indirect units, several heat exchangers are installed - this reduces the water heating time. To reduce the heating time of water and to cool the tank more slowly, it is better to choose models with thermal insulation.

Which boilers can it be connected to?

Indirect heating boilers can work with any source of hot water. Any hot water boiler is suitable - solid fuel - using wood, coal, briquettes, pellets. You can connect to any type of gas boiler, electric or liquid fuel.

It’s just that, as already written above, there are models with their own controls, and then their installation and wiring is more simple task. If the model is simple, you have to think through a system for regulating the temperature and switching the boiler from heating radiators to heating hot water.

Tank shapes and installation methods

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

If we talk about shape, then most often these devices are made in the shape of a cylinder. In almost all models, all working terminals (connection pipes) are located at the rear. It's easier to connect and looks better. On the front part of the panel there are places for installing a temperature sensor or thermostat; in some models it is possible to install a heating element - for additional heating of water when there is 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 only work effectively if the boiler power is sufficient.

Connection diagrams and features

There are two principles for connecting an indirect heating boiler: with and without priority for heating hot water. When heating with priority, if necessary, all the coolant is pumped through the boiler heat exchanger. It takes a little time to heat up. As soon as the temperature reaches the set temperature (controlled by a sensor, thermostatic valve or thermostat), the entire flow is again directed to the radiators.

In schemes without priority for water heating, only a certain part of the coolant flow is directed to the indirect water heater. This results in the water taking a long time to heat up.

When connecting an indirect heating boiler, it is better to choose a scheme with priority - it provides hot water in the required quantity. At the same time, heating does not suffer much - 20-40 minutes are usually enough to heat the entire volume of water, and 3-8 minutes to maintain the temperature at a flow rate. During such a time, no house can cool down enough to feel it. But this is provided that the boiler power is comparable to the boiler power. Ideally, the boiler is more productive, with a margin of 25-30%.

General rules

To ensure the normal operation of all devices connected to the hot water comb, a expansion tank for hot water (not for heating). Its volume is 10% of the tank volume. It is necessary to neutralize thermal expansion.

Also, shut-off valves (ball valves) are installed in each connection branch. They are needed so that each device can be used - a three-way valve, a circulation pump, etc. — if necessary, disconnect and service.

Check valves are usually also installed on supply pipelines. They are necessary to eliminate the possibility of backflow. In this case, connecting an indirect heating boiler will be safe and easy to maintain.

Installation next to the boiler in a forced circulation system (with 3-way valve)

If the system already has a circulation pump, and it is installed on the supply side, and the forced heating boiler can be placed next to the boiler, it is better to organize a separate circuit that comes from the heating boiler. This connection of an indirect heating boiler is implemented with most wall-mounted gas or other boilers that have a circulation pump in the supply pipe. With this connection diagram, it turns out that the water heater and heating system are connected in parallel.

With this piping method, a three-way valve is installed after the circulation pump, controlled by a temperature sensor (installed on the boiler). One of the outputs of the three-way valve is connected to the boiler pipe to connect the heating. A tee is cut into the return pipeline before entering the boiler, and a pipe is connected to it to drain water from the heat exchanger. Actually, the connection to the heating system is completed.

The operating procedure of this scheme is as follows:

• When information is received from the sensor that the water temperature is below the set temperature, the three-way valve switches the coolant to the boiler. The heating system turns off.
• The entire coolant flow goes through the heat exchanger, the water in the tank is heated.
• The water heats up enough, the three-way valve redirects the coolant to the heating system.

As you can see, the circuit is simple, its operation is also clear.

Scheme with two circulation pumps

Pir installation of water heater in the system in circulation pump, but not next to it, but at some distance, it is better to install a circulation pump in the circuit on the water heater. Connecting an indirect heating boiler for this case is shown in the diagram below.

The circulation pump can be installed either on the supply pipe or on the return pipe. In this scheme there is no three-way valve; the circuit is connected through ordinary tees. The coolant flow is switched by turning the pumps on/off, and it is controlled by a temperature sensor, which has two pairs of contacts.

If the water in the tank is colder than that set on the sensor, the power circuit of the circulation pump in the boiler circuit is turned on. When a given degree of heating is reached, the contacts of the pump close, which drives the coolant into the heating system.

Scheme for a non-volatile boiler

In a scheme with a non-volatile boiler, in order to ensure priority for the boiler, it is desirable that it be located higher than the radiators. That is, in this case, it is desirable to install wall-mounted models. IN ideal— the bottom of the indirect water heater is located above the boiler and radiators. But such an arrangement is not always possible.

The circuits will also work when the boiler is located on the floor, but the water will heat up more slowly and in the lower part it will not be hot enough. Its temperature will be comparable to the degree of heating of the return pipeline, that is, the supply of hot water will be less.

With energy-independent heating, the movement of the coolant occurs due to the force of gravity. In principle, you can connect an indirect heating boiler according to the traditional scheme - with a circulation pump in the circuit to heat it. It’s just that in this case, when the electricity is turned off, there will be no hot water. If you're not comfortable with this twist, there are several designs that will work with gravity systems.

When implementing this scheme, the circuit that goes to the water heater is made with a pipe with a diameter 1 step larger than the heating one. This ensures priority.

In this scheme, after the branch, a thermostatic head with an overhead sensor is installed on the heating system. It runs on batteries and does not require external power. The thermohead regulator sets the desired water heating temperature (not higher than the boiler supply temperature). While the water in the tank is cold, the thermostat opens the supply to the boiler, and the flow of coolant goes mainly to the boiler. When heated to the required degree, the coolant is redirected to the heating branch.

With coolant recirculation

If present in the system, constant circulation of water through it is necessary. Otherwise it won't work. All consumers can be connected to the recirculation loop. In this case, hot water will be constantly circulated by the pump. In this case, by opening the water at any time, you will immediately receive hot water - you will not need to wait for cold water to drain from the pipes. This is a positive thing.

The negative is that by connecting recirculation, we increase the cost of heating water in the boiler. Why? Because the water cools down as it runs around the ring, therefore the boiler will be connected to heating water more often and will spend more fuel on it.

The second disadvantage is that recirculation stimulates the mixing of water layers. During normal operation, the hottest water is at the top, from where it is supplied to the DHW circuit. When stirring, the overall temperature of the supplied water drops (at the same settings). However, for a heated towel rail this is perhaps the only way out.

How to connect an indirect heating boiler with recirculation? There are several ways. The first is to find special indirect units with built-in recirculation. Very convenient - the heated towel rail (or the entire loop) is simply connected to the corresponding pipes. But the price of such water heater options is almost twice as much as the price of a conventional tank of the same volume.

The second option is to use models that do not have an input for connecting the recirculation circuit, but connect it using tees.

In private homes, cottages, sports complexes and hotels, an indirect heating boiler is often used - the water heater operates without being connected to a centralized water supply. This equipment copes with heating large volumes of water, easily maintains the desired temperature and ensures an uninterrupted supply of hot flow.

In a word, if you are looking for a budget water heater to go with a single-circuit boiler, consider installing a BKN in your home. And to simplify the task of choosing, we suggest that you familiarize yourself with the criteria for purchasing a boiler, the principle of its operation and connection diagrams.

An indirect heating boiler can only operate on resources external source, but to service the system in the warm season, you can connect a heating element.

To ensure uninterrupted supply, the system includes a recirculation circuit - water will constantly move through the pipes, and when the tap is opened, a hot stream will flow at the water collection points connected to the circuit.

An indirect heating boiler is usually installed next to a heating boiler, and this “duet” occupies a fairly large area, especially if both devices are floor-standing.

Thus, the device allows you to significantly save on energy resources, but at the same time receive no less comfort than when using a centralized hot water supply system.

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The rate of heating of water depends on the number of turns on its spiral. The operating principle of this design of an indirect heating boiler is extremely simple: cold water enters the tank, and the coolant, moving along the coil, warms it up to the desired temperature.

But there are also devices designed according to the “tank-in-tank” scheme, where instead of a spiral pipeline, two containers of different diameters are used.

The system works like this: cold water enters a smaller tank, which is heated by hot coolant circulating between the walls of the tanks.

In such devices, water becomes warm in a matter of minutes - a large heating area allows the equipment to operate effectively in flow mode, guaranteeing an uninterrupted supply of hot flow.

A combined BKN for heating water can use energy from several sources at once or be equipped with a built-in heating element.

Types of KN boiler

By location:

• Wall– usually this is a small device with a displacement of up to 200 liters. Attaches using special brackets to any vertical surface strong enough to support the weight of a fully filled tank ( plasterboard partitions definitely won't fit). It can be located high enough and not occupy usable area rooms.
• Floor– a spacious boiler designed for a large number of consumers. However, for a device with a capacity exceeding 1000 liters, it is recommended to allocate a separate room -. But such a system is usually installed to serve large cottages, enterprises, hotels and other institutions; for family use, you can get by with a 250-300 liter device.

According to the shape of the tank:

• Horizontal– takes up a lot of space, but is easier to maintain independently required level water without connecting pumps.
• Vertical– saves free space, but is very limited in capacity.

Depending on the nuances of use, layout features and availability of free space, you can choose optimal model BKN, which will organically fit into the design of the room and provide your home with an uninterrupted supply of hot water.

What to look for when choosing 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.

• 80-100 l– 2 consumers;
• 100-120 l- 3 persons;
• 120-150 l– 4 users;
• 150-200 l– 5 consumers.

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 check when purchasing how much water actually fits in the device. This nuance should be indicated in the technical specifications.

Also, in addition to the “universal” 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 rather than take a quick shower, the working capacity of the tank should be appropriate - at least 120 liters.

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

Other important parameters:

1. Power– the greater the water consumption, the longer the device’s lifespan 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 energy source). For example, if the volume storage tank varies between 120-150 liters, the boiler power must be at least 23 kW, and for 160-200 liters you will need 31-39 kW.
2. Heating time– a parameter depending on the volume of the tank and the number of turns on the coil (large or combined containers can be equipped with several spirals).
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 allows heat to pass through, so it is better to purchase a more expensive device that uses polyurethane.
5. Control– the device will be able to operate in automatic mode, turning off and starting the water flow as necessary, and 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. This is how heat transfer is most efficient.

You can make an indirect heating boiler yourself. Instructions for manufacturing the unit are described in.

Nuances and boiler connection diagrams

As already mentioned, BKN uses energy from an external source to heat water. Therefore, before connecting to the coolant, it is important to select a suitable diagram for installing the device. Let's look at the most common options.

General principles for installing the device

The boiler must be mounted on a prepared, flat surface in close proximity to the boiler. Hanging models are mounted on a concrete or brick wall, at the same level or slightly above the heating boiler.

For a floor-standing device, the area allocated for placing the tank should be leveled (if the floor is critically uneven, you can make a stand in the form of a podium).