Characteristics of storage water heaters of indirect heating. What is an indirect heating boiler. With coolant recirculation

Article plan

If you live in a private house, then installing a boiler indirect heating together with the boiler will allow you to kill two birds with one stone - to heat the house and provide constant access to hot water. We have selected for you best models water heaters that can be found on sale today - choose!

Briefly about the main characteristics

In conventional storage water heaters, the liquid temperature rises due to the operation of heating elements, while in boilers, heating is carried out due to the circulation of a heated coolant in the system. It looks something like this: water is heated in a single- or double-circuit boiler and fed through pipes to a coil or other heat exchanger installed in the tank; at the same time, cold water, which is subsequently heated by heat transfer through the walls of the coil. Instead of a coil, a tank-in-tank design can be provided. In this case, the coolant is supplied to the external tank, and the heated liquid is supplied to the internal one. The presence of temperature and liquid volume sensors inside the tank, as well as automatic relays, ensure the smooth operation of the equipment. Some models are also equipped with additional electric heaters - even in case of force majeure, you can use the boiler hot water. Everything seems to be simple, but before buying it is necessary to understand the main technical characteristics of such equipment.

Reminder for future purchases

Selection criterion	Varieties	Note
Volume of the tank	from 50 to 400 liters and more	In the most popular models for domestic use, tanks with a volume of 80 to 200 liters are used. The volume is selected based on the flow hot water and the number of water points.
Power	from 2 to 60 kW and above	Together with the volume of the tank, the power determines the rate of heating of the liquid. The more powerful the equipment and the smaller the capacity, the faster the heating goes.
Max water pressure	6-10 bar (0.6-1 MPa)	The pressure that the boiler can withstand in operating mode. It is advisable to install pressure reducers to prevent damage from water hammer.
Mounting method	Wall	Equipment with a small tank volume (up to 100 liters) is often attached to the wall. The larger the volume, the more difficult it is to do this, so capacious water heaters are made in the floor version.
	Floor
	Combined
Heat exchanger design	Coil	The heat carrier from the boiler is supplied through a metal coil installed in a tank with heated water. The most common type.
	coil in coil	The heat exchange area is increased due to the use of two coils with different diameter spirals.
	Tank in a tank	There are two steel tanks - one inside the other. The coolant from the boiler is supplied to the larger tank, heated water is supplied to the smaller one.
Heat exchanger material	Stainless steel, brass	The vast majority are made of stainless steel. However, this material may vary in quality. Therefore, you should not save and buy products of an unknown brand.
Material and thickness of the thermal insulation layer	Foam rubber, mineral wool, expanded polystyrene, polyurethane foam - from 20 to 60 mm thick	The effectiveness of thermal insulation is determined by the value of thermal conductivity (the less, the better) and the thickness of the insulation layer (the more, the better). To date, a good solution is the use of 50-60 mm polyurethane foam insulation.
Maximum productivity in flow mode when heated to ΔT °C, l/min	where ΔT °C = 25, 45, 55 etc.	Determines the efficiency of the heater in flow mode. Depends on its power.
Heating time per ΔT °C, min.	where ΔT °C = 25, 45, 55, 60 etc.	Determines the heating rate of the entire volume of water in the tank. Depends on size and power.
Options	heating element	Many models can be upgraded with tubular electric heaters that fire when the boiler is turned off.
	recycling	The tank may be provided with a circuit for water circulation using a pump. This is necessary so that water is supplied to the consumer at a constant temperature.
	Solar collectors	The use of solar energy to heat the coolant with the subsequent transfer of heat to water heating. Collectors are installed on the roof. In the CIS, this option is relevant only in the warm season.
	Heat pump	Connectivity heat pump to minimize the cost of heating cold water. A very rare option.

We omitted such a parameter as the thread diameter for connecting to pipes, because. this issue, if necessary, is solved by installing adapters.

Calculation of the volume of water

Only you can determine exactly the required volume, because. calculations are tied to the conditions of water consumption. Our task is to provide information that will somehow help in the choice or suggest thoughts when making the calculation. For example, we open SNiP 2.04.01-85 and see that the norms set 7.9-10.9 liters of hot water (HW) per hour per person. Following some simple calculations, we get the following table.

These calculations can only be taken into account if the water heated by the boiler is consistently used and one draw-off point is operating at the same time (only one tap is open). In practice, the given values \u200b\u200bmust be multiplied by 3-5. Why is this happening? Because the norms do not take into account the desire to bask in the shower (+20 l. HW) and take a bath (+80 l. HW), wash a mountain of dishes (+20 l. HW), etc. and so on. Take into account the peak loads on the boiler - choose the volume that is most suitable for your needs.

50-60 liters is enough for 1 person;
for 2-3 people you need to choose from models of 80-120 liters;
for a family of 3-5 people, the capacity of a boiler of 120-200 liters is enough

To make it easier for you to choose suitable model equipment, we have identified four product groups depending on the volume of the storage tank: up to 100, 200, 300 and 400 liters. All technical specifications are taken from open sources, and prices are provided for comparison purposes only.

Important! Please note that some water heaters are only suitable for certain models of boilers. In the description, we will focus on this, but we recommend that you clarify all the nuances before buying.

Up to 100 liters

1. Baxi Combi 80 (80 liters) - from 52,500 rubles.

A notorious Italian player specializing in heating and water heating equipment, Baxi has been holding the quality mark for decades. The Baxi Combi 80 small volume boiler model is designed to work in conjunction with the LUNA-3 Comfort series boilers of the same manufacturer. Placement is floor, the water heater can be installed directly under the boiler, saving space. One of the advantages of this system is its compact dimensions. Corrosion protection is provided by the use of stainless steel and a magnesium anode. Polyurethane foam is used as thermal insulation. TENA connection is not provided.

2. Gorenje GBK80ORRNB6 (72.6 liters) - from 24,000 rubles.

When looking for a small model that can provide hot water for one or two people, pay attention to Slovenian equipment. This is a classic compact boiler with two tubular heat exchangers, the performance of which is enough for two points of water intake at once. The device is equipped with an electronic control unit and allows you to change the DHW temperature in the range of 15-75 °C. It has outlets for connecting to the boiler on the right side, two dry heating elements are installed as an additional heater. The model is equipped with several types of protection: against corrosion (magnesium anode), against freezing (effective thermal insulation), against overheating and heating without water. The manufacturer also provides a function to control legionellosis (a lung disease whose pathogens actively multiply in hot water). One of the best combined solutions in terms of price / quality ratio.

* operating parameters in flow mode are not specified by the manufacturer. The power of the heat exchanger itself is not indicated - only for the heating element.

3. Protherm FS B100S (95 liters) - from 36200 rubles.

The Czech boiler is structurally tied to the boilers of the same manufacturer - the Bear. Compact, with a concise but informative control panel, it easily fits into the kitchen interior as built-in appliances. Enamelled stainless steel, magnesium anode and antibacterial coating - all aimed at protection against corrosion and microorganisms. The tubular heat exchanger provides a high rate of heating of the entire volume of liquid: water is heated by 50 degrees in 13 minutes. To keep warm, the product is protected by a polyurethane foam coat.

4. ACV COMFORT 100 (100 liters) - from 48,000 rubles.

The Belgian manufacturer with almost a century of history offers interesting solution based on a tank-in-tank heat exchanger - model . The boiler consists of two stainless steel containers of different volumes, one of which is inserted into the other. Particular attention should be paid to the internal container: its surface is corrugated, therefore, due to thermal expansion, a change in size takes place, followed by the removal of the formed plaque of hardness salts (scale). The equipment is installed on the floor by default, but with the help of additional fixings it is possible to mount it on the wall. The heat-insulating layer is made of polyurethane foam 30 mm thick. Kit standard features small, but you can optionally install a control panel. It is also worth considering the lack of the possibility of recycling and connecting the heating element.

Up to 200 liters

5. Baxi Premier plus 150 (150 liters) - from 50,600 rubles.

It is possible to ensure the full operation of two hot water points with the help of. In a series of these heaters, a tubular coil-in-coil heat exchanger is used. Due to its low weight, the device can be hung on a wall or placed on the floor. The parts of the structure that come into contact with water are made of DUPLEX stainless steel, the minimization of heat losses is achieved by the use of polyurethane foam. The model is equipped with a thermostat and can be used in conjunction with any type of boilers. Optionally, it is possible to connect a tubular electric heater. The manufacturer has provided for the connection of the recirculation circuit. According to reviews, this is one of best solutions value for money for a family of four.

6. BOSCH WSTB 160 (160 liters) - from 28,000 rubles.

If a gas boiler is installed in your house, then you should think about buying a water heater. Although there is no possibility of connecting a heating element here, there is a recirculation system. The model is adapted to the harsh conditions of use in the CIS, i.e. suitable for hard water. To protect steel from corrosion, the material is coated with a special composition of glass-ceramic. There is a recirculation line so you can always count on getting water at a constant temperature. To minimize heat losses, a fur coat of 50 mm polyurethane foam is provided, the lining is made of PVC, soft. Frontal connection, it is possible to connect a temperature sensor. The entire volume is heated to ΔT=45°C in 37 minutes.

7. Protherm FE 200 BM (184 liters) - from 41650 rubles.

Many manufacturers offer storage heaters that are only suitable for their boiler models. If you installed a Proterm boiler, then to meet the needs of a large family in hot water supply, you should think about installing it. This is an indirect floor standing boiler made of stainless steel, enameled for corrosion protection. The installed titanium anode serves the same purpose. To prevent bacteria from multiplying on the walls of the container, they are covered with a layer of antibacterial substance. Productivity is high - with a delta of 25 degrees, you can get more than 30 liters of water per minute. Without the possibility of connecting the recirculation line and heating element.

8. Gorenje GV 200 (188.9 liters) - from 25,800 rubles.

Floor water heater of indirect type Combustion GV 200 - simplicity of the device, reliability of a design and laconic design. The product is an enameled steel tank with a tubular heat exchanger inside. Installed on the floor under the boiler. An overpressure relief valve is used as protection against overheating. The device is protected from corrosion by enamel and magnesium anode. It takes up to 24 minutes to heat the entire volume of water in the tank from 15 to 75 degrees. A 40 mm thick thermal insulation layer is responsible for maintaining the temperature of the hot water supply.

* the possibility of working in flow mode is not announced by the manufacturer

Up to 300 liters

9. ACV COMFORT 240 (240 l.) - from 65,000 rubles.

Another representative of indirect water heaters that use a tank-in-tank heat exchanger. The model is able to provide hot water to three points of water intake. The product is protected from corrosion due to the use of stainless steel and a special approach to the formation of the walls of the inner tank. Here it is corrugated, which has a positive effect on its work even with very hard water. At the same time, the equipment is characterized by the same features as for products of the same series: a minimum of functions, a thermal insulation layer of 30 mm, the inability to connect a tubular electric heater and a recirculation circuit.

10. Protherm FS B300S (295 liters) - from 63,000 rubles.

This accumulator is intended for use with Proterm Grizzly or Bizon boilers. - a capacious tank with a tubular heat exchanger. There are two flanges in the tank: for installing a heating element and servicing the boiler. Enamelled surfaces that come into contact with water, as well as the presence of a titanium anode, protect equipment from corrosion. Not to mention the presence of an antibacterial coating. A layer of polyurethane insulation is responsible for reducing heat loss. The device is characterized by high performance in flow mode, it is possible to connect a recirculation line. The possibilities of this heater will be appreciated by the owners of large private houses with more than three bathrooms.

11. Baxi Premier plus 300 (300 liters) - from 70,000 rubles.

Often the main criterion for choosing a boiler is not only its volume, but also the heating rate. In this case, it is relevant to consider models with a coil-in-coil heat exchanger. - exactly what is needed! Firstly, it is compatible with any boilers. Secondly, high-quality stainless steel, perfectly protected from corrosion, is used for its production. Thirdly, with a fairly compact size and low weight, the equipment has a universal placement and is equipped with an accurate thermostat. The model allows you to supplement the system with a recirculation circuit. Connecting a heating element for 2.7 kW is optional.

Up to 400 liters

12. Drazice OKC 400 NTRR / 1 MPa (380 liters) - from 68,000 rubles.

The Czech boiler is equipped with two tubular heat exchangers, one of which is designed to be connected to a solar collector, and the second to the boiler. This allows you to save a lot on heating water on sunny days, especially in summer. If necessary, for example, a malfunction of the boiler equipment, two auxiliary electric heating elements can be mounted. The enameled tank, as well as the presence of a magnesium anode, provide long-term protection of the tank from corrosion. 50 mm rigid polyurethane foam is used as a heat-insulating layer. There is a recirculation pipe.

Information on the rate of water heating in flow mode is not provided by the manufacturer. This is due to the presence of two independent heat exchangers with different temperature regime work.

13. Bosch SK 400-3 ZB (388 l.) - from 59,500 rubles.

There are not many indirect water heaters of the capacity we are interested in in the Bosch assortment, but among them there is a special model - Bosch SK 400-3 ZB. This is an enameled tank with a stainless steel coil. Corrosion protection is represented by a magnesium anode, which has already become a natural phenomenon in such equipment. The device is quite simple: a built-in thermometer and a flange for easy maintenance. At the same time, it is possible to connect a hot water recirculation line, as well as synchronize with the boiler if the latter has an NTC sensor connector (thermal sensor). Those. you can fine-tune the operation of water heating equipment. Separately, it must be said about thermal insulation. Here it is not polyurethane foam, but made of rigid foam, which, with equal thickness, gives a lower heat-shielding effect.

14. BAXI UBVT 400 SC (395 l.) - from 58100 rubles.

If the prevailing part of the boilers is designed to work in tandem with the boiler, then the model is an exception to the rule. It is adapted for connection to a solar collector, so its purchase will be appropriate in two cases: in places with year-round sunny weather or for seasonal use. Additionally, for heating, it is possible to install electric heaters. The container itself is made of steel coated with titanium enamel - it turned out to be a corrosion-resistant and durable coating. The latter is also facilitated by the presence of a magnesium anode. The kit includes a thermometer for temperature control, there are sockets for connecting sensors. The design provides a flange for monitoring the condition of the coil, as well as a built-in pipe for recirculation.

15. Hajdu STA 400 C (400 liters) - from 64,100 rubles.

The model from the notorious Hungarian manufacturer is interesting in that with one heat exchanger, fine-tuning of the equipment is possible. So, in the cold season, such an indirect heating boiler can be configured to work in tandem with the boiler, while in the summer it can be connected to a solar collector. In the latter case, if necessary, the heating element is additionally connected. The tank and heat exchanger are protected from corrosion by a layer of hot enamel and a magnesium anode. To minimize heat loss, the container is covered on the outside with a layer of polyurethane foam protected by a plastic casing. A branch pipe is provided for connecting a DHW recirculation system.

In the next video, this boiler is presented in section.

Editor's Choice

For ease of comparison, we will enter the main characteristics in the table and decide on the most successful models. To make it clearer, we choose a boiler for 1-2 people, 2-4 people, 4-6 people. (marked in the table below in bold from top to bottom, respectively). Because not all manufacturers adhere to common standards upon registration technical documentation, for example, not everyone indicates the value of performance in the flow mode, then we introduce the characteristic N. It shows the ratio of the unit of power per 1 liter. water. Those. we simply took and divided the capacities indicated by the manufacturer by the useful volume of drives. The larger this value, the faster the heating takes place.

Rating of indirect heating boilers

Model name	Useful volume, l	power, kWt	N, kW/l	Accommodation	heat exchanger	heating element	rec-tion	price, rub.
80	31	0,3875	outdoor	coil	—	—	52500
72,6	2	0,027548	wall	coil	+	—	24000
	95	26,1	0,274737	outdoor	coil	—	—	36200
100	23	0,23	floor/wall	tank in a tank	—	—	48000
	150	30	0,2	floor/wall	serpentine in serpentine	+	+	50600
160	20,8	0,13	wall	coil	—	+	28000
184	43,2	0,234783	outdoor	coil	—	—	41650
188,9	17,6	0,093171	outdoor	coil	—	—	25800
240	53	0,220833	floor/wall	tank in a tank	—	—	65000
Gorenje KGV 300-2/BG	280	69,6	0,248571	outdoor	coil	+	+	83700
295	46	0,155932	outdoor	coil	+	+	63000
300	30	0,1	floor/wall	serpentine in serpentine	+	+	70000
380	57	0,15	outdoor	coil	+	+	68000
388	60	0,154639	outdoor	coil	—	+	59500

To organize the supply of hot water, powered by a heating system, a double-circuit boiler is installed. Its disadvantage is low performance. Hot water is only enough for washing hands or dishes. For comfortable bathing, it is better to install an indirect heating boiler, the advantage of which is a storage tank.

The basic principle of operation of an indirect heating boiler is to circulate the coolant through a heat exchanger connected to the heating system. The hot liquid is pumped by the pump. The internal circuit of the boiler is enclosed in a storage tank, where cold water coming from the water supply system is heated from the energy of the coolant.

The circulation of the heating system has a vicious circle. Having given up energy, the coolant returns to the boiler through the pipes. The cycle is repeated while the pump and boiler are running. The rate of water heating inside the storage tank depends on the thickness of the coil pipe.

Design features

To better understand the work, it is necessary to study the device of the indirect heating device and understand how it differs from its counterparts.

The water heater is intended for systems of heating of the closed and open type. The main difference is the energy source. If gas water heater works from bottled or main gas, and electrical appliance from the heating element, then the internal circuit of the indirect heating boiler consists of a coil. The coolant is the source of energy. The coil is equipped with an inlet and outlet for connection to the heating system.

There are bivalent water heaters with two heat exchangers, where a heat carrier is supplied to one coil from the heating system, and heat is supplied to the other circuit from a solar system or a heat pump. If desired, the coils can be combined with fittings. It will turn out an indirect heating water heater with one circuit.

The heat exchanger is enclosed inside the storage tank, where the indirect heating of the water takes place. To connect to the water supply, the tank is similarly equipped with an inlet and outlet pipe. The shape of the storage tank is usually a cylinder, but there are rectangular models. So that the water inside the tank does not quickly cool down, it was enclosed in a decorative case, and the space between them was filled with thermal insulation.

A magnesium or titanium anode protects against scale formation. The heating element is installed inside the storage tank. The anode protects the metal parts of the boiler from galvanic corrosion and also reduces water hardness.

A thermostat is a regulator with which to reduce or increase the flow of coolant into the heat exchanger. The mechanism allows you to adjust the temperature of water heating.

When choosing a boiler for home use, it is better to give preference to a model where a heating element is additionally provided. The device combines indirect and electric water heater. The heater allows you to heat water in the summer when the heating system is not working. To regulate the heating of water from electricity, an additional thermostat and automation are installed.

Varieties

Most often, an indirect heating boiler with a coil is found on sale. However, there are models assembled according to the "tank in the tank" system. The principle of operation remained unchanged, only instead of a coil, an additional capacity acts as a heat exchanger. The advantage of the tank-in-tank system is the larger heating area. To connect the heating system pipe to the tank, an inlet and outlet pipe is similarly provided.

By type of installation, indirect water heaters are:

Wall models are limited to a storage tank of up to 200 liters. The water heater is hung on steel brackets. The main requirement is a solid wall. A hollow plasterboard partition will not withstand a water tank.
The floor water heater is designed for a large capacity. Household models are usually produced with a storage capacity of 250-300 liters. The floor boiler for industrial use can hold more than 1000 liters of water. Due to the large dimensions, a separate room is allocated for the water heater.

According to the type of tank location, an indirect boiler is:

Horizontal models are roomy. It is more convenient to maintain the water level, but the water heater takes up a lot of space.
Vertical models are smaller. The advantage of a water heater is its compactness and saving usable room space.

According to the material of manufacture of the storage tank, boilers are of three types:

All cheap models are equipped with an enameled steel tank. After a couple of years, the protective layer is broken and a leak appears.
Glass-ceramic tanks are one step higher in quality. The service life is increased, but they are also more expensive.
Stainless steel tank is expensive. However, the service life is unlimited. The water heater will last for many years, if you do not come across a low-quality fake.

A variety of indirect water heaters allows the consumer to choose the optimal model in terms of shape, cost, and capacity.

Positive and negative characteristics

Considering the pros and cons of indirect water heaters, we must dwell on the main advantage - energy savings. You will have to pay separately for the gas and electric boiler. The indirect water heater receives energy free of charge from a working heating system.

Other benefits stand out:

Long service life. The heating of the heat exchanger does not form solid accumulations. Scale appears during the operation of the heating element, but it is not turned on all year round, but only in summer.
A water heater with two heat exchangers or a tank-in-tank system is characterized by high performance.
The model with an additionally installed heating element combines two important parameters: efficiency in winter, efficiency in summer.
Having welding experience, an indirect water heater can be made independently.

The downside is the complexity and high cost of installation. The first heating of the container takes a long time, but then the water temperature is constantly maintained. In the absence of heating elements in the summer it is impossible to get hot water.

How to choose an indirect heating boiler

Do right choice a suitable indirect heating boiler model is a difficult task for a beginner. However, there is nothing overwhelming here, you just need to take into account a few important nuances:

When choosing a water heater with indirect heating for an apartment or a private house, the first step is to determine the optimal volume of the storage tank. In order for all family members to have enough hot water, they calculate taking into account the approximate consumption of 100 liters per day by one person.
An indirect water heating boiler is economically beneficial for a family of four or more people. With this number of people, the approximate consumption of hot water is 1.5 l / min.
Paying attention to the volume of the tank, take into account the heating time. Large capacity will take longer to heat up. It may be worth giving preference to a model with two heat exchangers or a tank-in-tank system.
The composition of the thermal insulation determines how long the water will remain hot after the boiler is turned off. Cheap water heaters come with foam. Porous material poorly retains heat and quickly decomposes. The optimal thermal insulation is mineral wool or polyethylene foam.
To make the right choice, you need to compare the power of the indirect water heater and the heating boiler. If the latter is characterized by weak parameters, the boiler will become an unbearable load.
When buying any model, be sure to pay attention to the presence of a thermostat, valve and other protection elements.

When with everyone important nuances the issue is resolved, you can pay attention to the form, design, manufacturer and other details.

Calculation of the volume of the storage tank

To make an approximate calculation of the volume of the storage tank, you can use a simple reading of the water meter. When the same number of people constantly arrive at the house, the daily consumption will have the same data.

A more accurate calculation of the volume is based on counting the water points, taking into account their purpose and the number of living family members. In order not to go into complex formulas, the hot water consumption is taken from the table.

Connection diagrams for the heating system

When choosing a connection scheme for an indirect boiler for heating water, the location of the device in the house, as well as the features of the heating system wiring, are taken into account.

A simple and commonly used scheme is based on connecting an indirect device through a three-way valve. As a result, two heating circuits are formed: heating and hot water. After the boiler, a circulation pump crashes in front of the valve.

If the need for hot water is small, a system diagram with two pumps is suitable. The indirect water heater and the boiler form two parallel heating circuits. Each line has its own pump. The scheme is suitable for country houses where hot water is rarely used.

The connection diagram is more complicated if the house has a “warm floor” system installed along with radiators. To distribute pressure across all lines, and together with an indirect boiler they will get three, a hydraulic distributor is installed. The node normalizes the circulation of water through the "warm floor", water heater and radiators. Without distributor pump equipment will fail.

In indirect water heaters with recirculation, three nozzles come out of the body. Traditionally, two outputs are used to connect to the heating system. A looped circuit is led from the third branch pipe.

If the indirect water heating device does not have a third branch pipe, and recirculation must be done, then the return line circuit is connected to the cold water pipe and the recirculation pump is additionally inserted.

Recirculation allows you to get hot water at the outlet of the tap even before the liquid in the storage tank of the boiler is completely heated.

Popular Models

It is always necessary to choose a suitable model according to technical characteristics. As an aid, you can see the rating of indirect heating boilers, compiled taking into account consumer feedback.

Viessmann Vitocell-V 100 CVA-200

The model is equipped with a steel tank with an enamel coating with a capacity of 200 liters. Rapid heating of water is carried out by means of a heat exchanger with a total area of 1 m 2 . The temperature is controlled by a thermostat. The maximum allowable parameters: water heating - up to +95 ° C, inlet pressure - 10 atm.

Drazice OKC 200 NTR

The water heater is presented in two models: with one and two heat exchangers. The container is similarly designed for 200 liters of water. However, heating is carried out faster due to the increased heat exchanger area - 1.45 m 2. The disadvantage is the lack of a heating element, which does not make it possible to obtain hot water in the summer.

Roda Kessel ILW 200B

The powerful device with a 200 l steel storage tank is equipped with a copper heat exchanger. Additionally, the model is equipped with a heating element, which allows you to get hot water in the summer when the heating is turned off. The temperature is controlled by a thermostat. The maximum limit is +65 o C.

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

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

An indirect heating boiler can only operate on resources from an external source, but a heating element can be connected to service the system in the warm season.

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

An indirect heating boiler is usually installed next to the heating boiler, and this “duo” takes up 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 get no less comfort than when using a centralized hot water supply system.

Image Gallery

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

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

The system works like this: cold water enters a smaller tank, which is heated by a 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 efficiently 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.

Varieties of boiler KN

By location:

Wall- usually, this is a device small size with displacement up to 200 liters. Fastens with special brackets to any vertical surface, strong enough to support the weight of a fully filled tank (plasterboard partitions will definitely not work). It can be located high enough and not occupy the usable area of the room.
Floor- a capacious boiler designed for a large number of consumers. True, for a device with a capacity exceeding 1000 l, it is recommended to allocate separate room– . But such a system is usually installed to serve large cottages, businesses, hotels and other institutions, for family use, you can get by with a device of 250-300 liters.

Tank shape:

Horizontal- takes up a lot of space, but it is easier to maintain the desired water level in it without resorting to connecting pumps.
Vertical- saves free space, but is very limited in capacity.

Depending on the nuances of use, layout features and the availability of free space, you can choose the optimal BKN model that 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 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.

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 specify when buying how much water is actually placed in the device. In the technical specifications, this nuance should be indicated.

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:

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.
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).
tank material- for long-term use, boilers made of stainless steel or medical steel are best suited.
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.
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.

An indirect heating boiler can be made with your own hands. The instructions for manufacturing the unit are described in.

The nuances and schemes for connecting the boiler

As already mentioned, BKN uses energy from an external source to heat water. Therefore, before connecting to the coolant, it is important to choose a suitable scheme for mounting the device. Consider the most common options.

General principles for installing the device

It is necessary to mount the boiler on a prepared flat surface in the immediate vicinity of the boiler. Suspended models are mounted on concrete or brick wall, at the same level or slightly above the heating boiler.

For a floor-standing appliance, you should level the area reserved for the placement of the tank (if the floor is critically uneven, you can make a stand in the form of a podium).

Updated: 16.09.2018 15:03:29

Judge: David Lieberman

*Overview of the best in the opinion of the editors of the site. About selection criteria. This material is subjective, is not an advertisement and does not serve as a guide to the purchase. Before buying, you need to consult with a specialist.

Among the wide variety of water heaters, buyers show particular interest in indirect heating boilers. Outwardly, these models do not differ from conventional storage devices. Most often, manufacturers stop at a rectangular or cylindrical body shape. At indirect boilers has its pros and cons. Experts recommend paying attention to several technical parameters.

How to choose an indirect heating boiler

Power heater is selected taking into account the volume of the tank and the desired rate of water heating. When studying the documents for the boiler, it is necessary to take into account the useful power of the device.
capacity water heating tank depends on the number of users. To take a shower in the country for a couple of avid gardeners and gardeners, a 100-liter drive is enough. If the family is large, there are small children, then more capacious boilers (200-300 liters) should be preferred. But at the same time, the power of the heat exchanger should be greater so that the heating of the water does not drag on for a long time.
Heating rate also depends on the area of the heat exchanger. To find the optimal combination, you can start from the following ratio. The heating rate of water with a volume of 120 liters with a coil area of 1 sq. m will be about 30 minutes.
Reliability and durability boiler is largely determined by the quality of the tank. A stainless steel tank will last the longest, but the price of such models is high. Manufacturers cover tanks made of ordinary steel with enamel or glass-ceramic. Additionally, magnesium anodes help resist corrosion, they also protect the internal cavity from scale formation.
Maintain temperature water in a given interval helps thermal insulation. Budget boilers have a foam layer, more modern products are equipped with polyurethane foam insulation.
Functionality. Various options help to minimize human intervention in the operation of the boiler. These are overheat protection, safety valve, thermostats and thermometers.
Number of water intake points. With the help of a boiler, you can conduct hot water in several rooms. To do this, you need to choose a water heater with several points of water intake.

What is better indirect heating boiler or gas boiler

Boiler type

Advantages

Flaws

high power

Fast water heating

Easy setup and adjustment

Multiple water points

Inconvenience of ignition

Gas costs

High price

Indirect

Effective thermal insulation

Can be connected to different sources energy

High performance

No additional costs

Performance depends on the temperature of the coolant

Large dimensions and weight

Attachment to the source of energy

Rating of the best indirect heating boilers

Nomination	place	Name of product	price
The best indirect heating boilers with a volume of 100 l	1		62 100 ₽
	2		26 900 ₽
	3		18 361 ₽
The best indirect heating boilers with a volume of 150 l	1		39 451 ₽
	2		42 040 ₽
	3		21 700 ₽
The best indirect heating boilers with a volume of 200 l	1		49 250 ₽
	2		56 580 ₽
	3		24 600 ₽
The best indirect heating boilers with a volume of 300 l	1		114 000 ₽
	2		60 362 ₽
	3		36 400 ₽

The best indirect heating boilers with a volume of 100 l

Indirect boilers with a small tank (100 l) are in demand among single residents or families consisting of 2 people. Devices of this type are installed in apartments or cottages. The experts selected several models.

The most modern indirect heating boiler in design is the Belgian development ACV Smart 100. The water heater is a heat exchanger that uses two stainless steel tanks. The tank-in-tank system is different in that the coolant heats the contents of a small tank over the entire area. This approach allows for the same time to heat twice as much water as in the traditional way using a coil. The maximum temperature is limited to 90ºС.

Experts gave the first place in the rating of the model for high-quality thermal insulation. The manufacturer used polyurethane foam 50 mm thick, which is famous for its low thermal conductivity. Experts also speak flatteringly about the wavy surface of the tank, due to which self-cleaning of scale occurs.

Advantages

modern design;
effective thermal insulation;
self-cleaning from scale;
fast heating of water;

Flaws

high price.

The indirect heating boiler Electrolux CWH 100.1 Elitec allows you to heat water up to 100ºС. In this component, it outperforms its competitors. The capacity of this small water heater is 390 l/h. Both the heat exchanger and the steel tank are covered with a double layer of glass enamel. To extend the life of the boiler, a large magnesium anode is installed inside. The manufacturer also took care of the thermal insulation, the water remains hot for a long time due to the use of a 75 mm thick insulation. Additionally, you can install a heating element, which is relevant in summer time.

Although the device is somewhat inferior to the winner in innovation and efficiency, it is affordable, and the warranty period is 10 years.

Advantages

high performance;
reliable protective coating;
effective thermal insulation;
several points of water intake;

Flaws

small heat exchanger area;
big weight(55 kg).

At the most affordable price, the Gorenje GV 100 boiler is sold on the domestic market. The quality of the heater is quite high. The role of a heat source is played by a tubular carrier, which allows you to connect the boiler to various heating mains (even to central heating). Water can be heated up to 85ºС, the manufacturer has provided several points of water intake. The model has all the main options, it is a thermometer, indication of switching on and heating, overheating protection, safety and check valve. The heat exchanger is made of stainless steel, and the steel container is covered with enamel. Magnesium anode provides additional anti-corrosion protection to the tank. Users do not complain about the quality of workmanship, but the search for spare parts and mounting elements becomes a serious problem.

Advantages

versatility of connection;
low price;
rich functional content;

Flaws

lack of spare parts and accessories.

What is better indirect heating boiler or double-circuit boiler

HEATER TYPE

ADVANTAGES

FLAWS

INDIRECT HEATING BOILER

HIGH VOLUME

HIGH-QUALITY HEAT INSULATION

MINIMUM SCALING

HIGH PRICE

LARGE OVERALL DIMENSIONS

DOUBLE-CIRCUIT BOILER

AFFORDABLE PRICE

HIGH RELIABILITY

EASY OPERATION

LOW PERFORMANCE

PRODUCES A LOT OF SCALE

The best indirect heating boilers with a volume of 150 l

Boilers with a storage tank of 150 liters can provide hot water to residents of apartments or houses in the amount of 2-3 people. They are affordable and compact in size. Here are some successful water heaters.

The Vaillant uniSTOR VIH R 150/6 B indirect heating boiler has a stylish appearance. It can be installed in any premises, the manufacturer has provided for vertical mounting with top trim. The device allows you to heat water up to 85ºС, and the inlet pressure can reach 10 atm. A powerful heat exchanger (25.5 kW) quickly heats up the contents of the tank, and effective thermal insulation keeps the water hot for a long time. The tank is made of ordinary steel, which is covered with a layer of enamel. The magnetic anode becomes an additional way to protect the tank from corrosion.

Advantages

stylish design;
magnetic anode;
fast heating;
high water temperature;

Flaws

heavy weight (79 kg).

One of the most popular indirect heating boilers is the Italian Baxi model Premier Plus 150. The excellent quality of the product is recognized by specialists in different countries. The storage tank is made of stainless steel, which is highly resistant to corrosion. The efficient polyurethane foam insulation helps keep heat loss to a minimum. A tubular coil will cope with fast and uniform heating of water.

The high strength and reliability of the boiler is perfectly combined with lightness (31 kg), so the user can choose between wall or floor mounting.

Advantages

high efficiency;
effective thermal insulation;
lightness and compactness;
quality assembly;

Flaws

high price;
incomprehensible installation instructions.

The Hajdu AQ IND150SC floor heater attracts the attention of potential buyers with an affordable price. The model is capable of serving several points with hot water. The manufacturer provided for the possibility of installing an electric heater with a power of 2 or 3 kW. The inner surface of the tank is covered with glass enamel, which permanently protects the steel from corrosion. The heat exchanger is made of ordinary steel with protective enamel. Thermal insulation made of polyurethane foam in combination with a polymer paint layer on the outer surface allows long time keep the water hot.

Advantages

affordable price;
reliable thermal insulation;
good equipment;

Flaws

coil leaks are noted;
service difficulties.

The best indirect heating boilers with a volume of 200 l

Full-fledged families of 3-4 people need a lot of hot water, especially in the summer. Boilers of indirect heating with a volume of 200 liters are capable of ensuring uninterrupted supply. Experts have chosen the following models.

Users call the Viessmann Vitocell-V 100 CVA-200 boiler a reliable heating device. Its work is stable, the unit is easy to operate, the service life is more than ten years. Powerful heat exchanger (36 kW) with an area of 1 sq. m quickly heats water up to 95ºС. The steel tank is protected by an enamel coating, and a magnesium anode is additionally installed, which is powered by a third-party energy source. The manufacturer effectively isolated the tank from the outside world with the help of eco-friendly insulation.

The boiler deservedly becomes the winner of the rating for the optimal combination of price and quality. Users are satisfied with the reliability and uniform heating of water.

Advantages

fast heating of water;
long service life;
high heating temperature;
reliable protection against corrosion;

Flaws

not detected.

To speed up the process of heating water with a volume of 200 liters to a temperature of 90ºС, the Ariston BC2S CD2 200 boiler was equipped with two heat exchangers. Thanks to this constructive solution managed to bring the area of the heat exchanger to 1.8 square meters. m. The heater can be connected to gas boilers and solar collectors. The manufacturer has applied complex protection, the inner surface of the steel tank is covered with a layer of fine enamel. The magnesium anode helps fight corrosion. The layer of polyurethane foam allows to reduce heat loss. The thermostat prevents overheating of water, the device has a safety drain valve. In the absence of water in the tank, protection against turning on the heating is provided.

Experts put the boiler in the second position in the rating for its large weight (111 kg).

Advantages

two heat exchangers;
high performance;
the presence of protective options;
durable anti-corrosion coating;

Flaws

great weight.

Indirect heating boiler Hajdu AQ IND200SC was liked by specialists at an affordable price and stylish design. The model is able to heat water up to 65ºС at a maximum water pressure of 6 atm. Experts note good power (32 kW) and a large heat exchanger area (1.06 sq. M). To protect the inner surface of the tank, a glass-ceramic coating is applied, and the coil is made of an enameled pipe. The magnesium anode helps fight corrosion. The manufacturer has provided the possibility of installing an electric heater with a power of 2 or 3 kW.

Another boiler with a progressive "tank in tank" system becomes the winner in our ranking. This is the ACV Smart Multi-Energy 300 model, which is a floor standing version of the water heater. The device is designed to provide hot water to cottages, offices and production shops. A well-designed design allows you to connect the boiler to the heating systems of residential and industrial facilities. Thermal power is 32 kW, however, the storage device is economical. This is due to excellent thermal insulation, for 8 hours the water temperature drops by only 3ºС.

Experts highly appreciated the use of stainless steel for the manufacture of tanks and components, which makes the boiler exceptionally reliable and durable. In addition, it is also the lightest (99 kg).

Advantages

high power;
reliability and durability;
several points of water intake;
quality manufacturing;

Flaws

high price.

The high power of the Buderus Logalux SU300 indirect heating boiler is provided by a smooth-tube heat exchanger. It is able to quickly heat water up to 95ºС. The manufacturer chose to make the storage tank out of ordinary steel, thermal glaze was used in combination with a magnesium anode to protect against corrosion. Keep high temperature water is helped by thermal insulation made of thick polyurethane foam (50 mm), which does not contain dangerous fluorine and chlorine hydrocarbons.

The model is located on the second position not only because of the steel tank, the large weight (145 kg) also made a negative contribution. It is not surprising that the installation of the tank is provided only on the floor, and adjustable supports help to quickly level the boiler. Users like the model for the optimal combination of price and quality.

Advantages

quality assembly;
effective thermal insulation;
powerful heat exchanger;

Flaws

great weight.

The Hajdu STA300C indirect heating boiler has several advantages that helped it climb to the third step in the rating. Firstly, the model is sold in the domestic market at an affordable price. Secondly, you can connect the heater to different energy sources, starting from gas boiler and ending with a solar collector. The manufacturer uses the classic scheme to protect the steel tank from corrosion (glass-ceramic + magnesium anode). Heating efficiency is achieved by a powerful heat exchanger (45 kW) with a recirculation pipe. Possibility of installation of additional TEN is provided.

The boiler is not perfect in build quality, which has prevented it from climbing higher in the rankings. Users note a number of minor flaws that have to be eliminated on their own.

Advantages

connects to different energy sources;
affordable price;
installation of an additional heating element is allowed;

Flaws

build quality sucks.

Attention! This rating is subjective, is not an advertisement and does not serve as a purchase guide. Before buying, you need to consult with a specialist.