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Water Heaters 

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Water Heaters: specifications, types


In heaters, in addition to the classic, familiar to all boilers ( storage heaters) and gas water heaters, you can find flow-through wall-mounted, flow-through taps and boiling systems.

Flowing. Flowing water heaters are called water heaters that do not have built-in tanks — the water in such devices is heated directly in the process of passing through the heater. Compared to accumulative, such devices are more compact (due to the lack of a reservoir) and fast-acting — heated water comes out of them immediately. In addition, they are considered more energy efficient: during operation, only the water that is currently being used is heated, there is no need to waste energy on maintaining the temperature in the tank. At the same time, note that for efficient heating of running water at high pressure, a rather high power is required. For example, a shower will require an instantaneous electric heater with a power of at least 8 kW — and such power requires a special connection format, besides, weak wiring may simply not withstand the load. There are also less powerful instantaneous water heaters, however, their efficiency, respectively, will be lower. However, gas heaters are deprived of these shortcomings (see "Source of Energy") — in general, it is not difficult to provide the necessary power in them....r>
— Cumulative. Water heaters equipped with their own water tank; cold water is drawn into this tank, heated and already from the tank is supplied outside. It takes some time to heat up and the hot water in the tank is limited. Therefore, storage heaters are not designed for continuous operation, and when using such a device, you need to be careful not to use up all the hot water ahead of time. In addition, storage heaters are noticeably heavier and larger than flow heaters (and the larger the water supply, the larger and more expensive the device), and their energy consumption is generally somewhat higher, because. stored water cools down over time, and it must be regularly heated to a predetermined temperature. However, such devices have one key advantage: they do not require high power, they do not create such loads on the power grid as flow-through ones, and many fairly large storage boilers work without problems from a regular household outlet. In addition, the pressure of water from such a device can be almost any (whereas in flow models this moment, again, is directly limited by power).

— Boiling system. This type of water heater is a set of a tap, a small storage tank for water and additional filters. The installation of the device is very similar to reverse osmosis filters (with the exception of the mandatory presence of power supply) and flow heaters on the tap (see below) — only the tap is located in the visible area, the rest of the “organs” of the system are hidden from view. A key feature of boiling systems, which is why they got such a name, is the ability to heat water up to 100 °C, thereby several liters of boiling water always flow from the tap without waiting. Manufacturers position such systems as an alternative to kettles (naturally, if there is enough good quality water in the tap). It is worth considering that such sets exist in a truncated version (without a water tank), in which case they are in our catalog in the taps section.

— Flow to the tap. Flow heaters in the form of water taps. Devices of a similar form factor are installed instead of a standard tap directly on a kitchen sink, washbasin, etc. One of the advantages of their design is the minimum of additional equipment at the draw-off point: only one device instead of a separate tap and water heater.

Energy source

Gas. In such a device, it is easy to provide a high heating power — even in the most modest devices, it is calculated in kilowatts. However, gas models are difficult to install, since they require a gas line and a chimney gasket to remove combustion products. At the same time, the mentioned high power is relevant mainly for gas water heaters (instantaneous water heaters), and most gas models belong to this type. However, there are also storage gas water heaters.

Electric. Electric water heaters are versatile and easy to install — unlike gas, and they do not need a chimney. On the other hand, even for relatively low-power models (up to 5 kW), high-quality electrical wiring is needed, and more powerful heaters require a separate connection to the electrical panel or even a three-phase power supply. In addition, electric heaters are often considered more expensive to operate than gas heaters. This option is popular mainly among accumulative models (see "Type").

Indirect. Such water heaters do not have their own heating element (electric or gas). Its role is played by a heat exchanger, through which a coolant moves, heated by an external source (most often a heating boiler) — due to this, the water is heated. Indirect heaters are made only accumulative (see..."Type") — this is due to the design features. They cannot be installed autonomously — an external heating source is required; the installation process itself can be quite complicated. The main advantage of this option is that it does not require a separate supply of electricity or gas to heat water. In addition, an indirect heater allows more efficient use of heat from a boiler or other heater: the energy that could “fly out into the pipe” is instead used to heat water.

— Combined. Such water heaters are a kind of hybrid between indirect and electric. The main heating of the water in them is provided by a heat exchanger operating at the expense of an external source of heating (for example, a heating boiler) or a built-in heat pump. And an electric heating element (usually, a heating element — see "Heater type") serves for additional heating. Combined heaters provide a higher temperature than conventional indirect heaters and are more economical than electric ones. Their main disadvantage is their rather high cost.

Solar heating

Possibility of operation of a water heater from a solar collector. To be more precise, we are talking about the possibility of connecting an indirect or combined model heat exchanger (see "Type") to a solar collector. Such heating sources have their own characteristics, and for use with them it is worth choosing water heaters in which compatibility is directly stated. At the same time, only one of several water heater heat exchangers can be responsible for working with solar energy.


Regular way to install a water heater.

The choice for this parameter depends primarily on how much free space is available for installing the device and what shape this space has. Therefore, when there is a lot of space (for example, the user has an entire wall in the boiler room of a private house at his disposal), this parameter can be ignored. But in cramped conditions, each installation method will have its own nuances.

Vertical. Vertical arrangement devices, elongated in height. This option is well suited for narrow cramped spaces — for example, a bathroom in a small city apartment.

Horizontal. The horizontal layout is less suitable for tight spaces than the vertical one, but in some conditions it may be optimal — for example, if the place under the device looks like a low horizontal niche. Also note that many instantaneous water heaters are produced in this design (see "Type") — they do not take up much space, and horizontal orientation is considered optimal for such devices for a number of reasons.

Outdoor. Floor mount models (as opposed to all of the wall mount options described above). The main advantage of such an installation is simplicity: there is no need to drill walls and prepare other special fasteners, it is enough to have free space on the floor. In addition, weight restrictions are not so critical for floor water...heaters, and this method can be used even for the most powerful, capacious and, accordingly, large models. On the other hand, just free space on the floor is not always available, and this installation method is not suitable for cramped conditions.

— Universal (suspended). Devices that can be placed in any position — both horizontal and vertical (see above for details). The advantage of this option is obvious: the user can choose the installation method of his choice, depending on the situation.

Tank volume

The volume of the tank installed in the storage water heater (see "Type"). This is one of the key parameters for such devices. On the one hand, a large tank allows you to keep a large supply of water and reduces the risk that it will run out at the most inopportune moment; this is especially important when water consumption is high, such as in a large family. On the other hand, a volumetric tank correspondingly increases the size, weight and cost of the entire device, requires reliable fastenings (when installed on a wall), and more energy is spent on heating and maintaining the temperature of the water in it. Accordingly, when choosing, it is worth not chasing the maximum volume, but proceeding from the actual water consumption and from this point of view determine the optimal capacity of the tank.

There are special tables and formulas that allow you to calculate the optimal volume of the tank depending on the format of use (washbasin, shower, kitchen sink ...), the temperature of the water used and other parameters. These data can be found in special sources. Here we note that the smallest storage water heaters can hold only 5 liters; such devices are designed for washing, washing dishes for 1 – 2 people and other tasks that do not require a lot of water. The average indicator is considered to be a volume of 80 – 100 liters, such a tank is quite enough for an apartment in which 3 – 4 people live. And in the most "large-caliber" models, the volume is already calcul...ated in cubic metres; such heaters are designed, for example, for hotel buildings, showers in sports complexes and swimming pools, and other similar places where a lot of hot water is required.

2 tanks

The presence of 2 separate tanks for water in the storage water heater; usually, the total volume is divided equally between these tanks.

This design is noticeably more complex and expensive than the traditional 1-tank arrangement, but offers several advantages. Firstly, the containers can be heated in turn, which significantly speeds up the process: after all, in order for hot water to be used, it is enough to warm up only half of the total volume to operating temperature. Secondly, with this format of work, power consumption and the load on the power grid are reduced; and if at a certain moment the user does not need a lot of water, then the energy consumption turns out to be small (again, due to the fact that the entire volume does not need to be heated). Thirdly, compared to traditional models of the same volume, such boilers are thinner, which can simplify installation (the price for this advantage is an increase in width, but this moment is not so often critical). Fourth, this arrangement improves thermal insulation and reduces heat loss.

Hull shape

The shape of the water heater.

The traditional form options are cylindrical and rectangular, but nowadays there are more specific options — flat cases, narrow cylindrical devices. Here are the features of each of these options:

— Cylindrical. This form is actually traditional for storage water heaters. This is due to the fact that with the same total volume, less material is needed for a cylindrical tank than, for example, for a rectangular one; and in production, such containers are simple and cheap, which allows them to be used in boilers of any price category. The disadvantages of this form include, first of all, some bulkiness in comparison with other options.

— Rectangular. The case is rectangular in shape, with pronounced front and side faces; the corners can be both sharply defined and rounded. This is the traditional form for instantaneous water heaters, primarily gas, but it can be found in a fairly large number of storage models. Accordingly, the features of a rectangular case will be different — depending on the type of heater. So, in flow models, the “rectangle” is simply one of the most convenient options in terms of the overall layout. But in boilers, this shape differs from the flat one (see below) only with a slightly greater thickness and, in some cases, pronounced angles.

— Flat. A varia...nt found mainly in storage electric heaters. Such devices look as if the classic cylindrical body was flattened at the back and front, reducing its thickness by increasing the width (and sometimes height). Thus, such a boiler does not protrude as much in front of the wall as a cylindrical one; in some cases, this point may be fundamental — for example, when installed in a toilet, where a cylindrical device would hang over the toilet, creating discomfort.

— Narrow. A variety of cylindrical cases, characterized by a reduced diameter. In other words, boilers from this category are also round, but with the same volume, they have a noticeably smaller width and thickness than traditional cylindrical ones. In cramped conditions, this can be very useful; however, it must be borne in mind that the price for reducing the diameter is an increase in height.

Power source

The type of power required to operate the water heater.

230 V (1 phase). Powered by a single-phase household network at 230 V. At the same time, relatively low-power models (up to 3.5 kW) can be plugged into a regular outlet, with higher power a special connection format will be required. However, anyway, such devices are relatively easy to supply. On the other hand, in heaters of more than 10 kW, this option is practically not found.
Also note that it is this type of power that is used by all gas and indirect models, in which electricity is required only for the operation of control circuits. The power consumption of such circuits is small, and an ordinary outlet is enough for them, as they say, “with a head”.

400 V (3 phases). Powered by three-phase networks at 400 V. This power format can be called "industrial", connection to 400 V is available in specialized boiler rooms, workshops, workshops and other similar places, but in an ordinary residential area it may be difficult — it is likely that you will have to pull the wire to the street power line or switchboard. On the other hand, such power is suitable for heaters of any power, even the most "heavy". And if you have the opportunity to connect the heater to both 230 V and 400 V, it is better to choose the second option — it will provide a more reliable account of the energy consumed.

— Non- volatile. Water heaters that operate without power at all and do...not require an electrical connection. Only gas and indirect models can be non-volatile (see “Energy source”), however, not every gas or indirect heater belongs to this category.

Energy efficiency class

This parameter characterizes the efficiency of electricity consumption by the water heater. Classes are indicated by latin letters from A to G (A, B, C, D), where A is the most energy efficient device.

Power consumption

Electrical power consumed by the heater during operation.

This parameter is of key importance for electric models (see "Power source"): in them, the power consumption actually corresponds to the power of the heating element and, accordingly, the useful thermal power of the entire device. And the overall efficiency and performance of the water heater directly depends on the useful power. Accordingly, high-performance models inevitably have high consumption. At the same time, we note that the heating power is selected by the designers in such a way as to guarantee the necessary performance and water temperature. So when choosing a device according to performance, you need to look primarily at performance and temperature. Power must be taken into account when connecting: for example, if a 230 V model (see "Power") consumes more than 3.5 kW, it, usually, cannot be plugged into a regular outlet — connection is required according to special rules. And the most performant and high consumption models — 10 kW or more — are connected only to three-phase networks.

The power consumption has a similar value for combined boilers — adjusted for the fact that in them the electric heater is an additional source of heat. And for gas and indirect models, this parameter describes the power consumption of control circuits and other auxiliary structural elements; this power consumption is usually very small — on the order of several tens of watts, less often up to 1.5 kW.

Heating modes

The number of heating modes provided in the device.

This parameter is specified only for models with several heating modes. We emphasize that you should not confuse such functionality with temperature control (see "Functions"). The heating mode is the general format of the device; these formats differ primarily in such parameters as the actual heating power, the number (and in combined models, and types) of the heating elements involved, etc. And the thermostat, if it is in the design, allows you to change the temperature already within a specific mode.

In general, the presence of several heating modes expands the functionality of the water heater, but affects its cost. Well, of course, the specific features of these modes do not hurt to clarify in advance before buying.

Rated heat exchanger power

Nominal power of the heat exchanger installed in the gas or indirect heater (see "Energy source"), in other words, the amount of heat that can be transferred to the heated water through the heat exchanger.

This parameter is directly related to the performance of the water heater: high performance inevitably requires appropriate power. At the same time, the power of the heat exchanger is selected in such a way as to provide the necessary operating parameters (primarily performance and temperature). So when choosing a water heater, you should focus primarily on these parameters. Data on the power of the heat exchanger may be needed for some specific calculations — for example, assessing the compatibility of the heater with a boiler or solar collector: an external heat source must have no less thermal power than the heat exchanger, otherwise it will be impossible to achieve the claimed performance.

It is also worth considering that the actual power of the heat exchanger depends on the temperature of the coolant flowing through it. In the characteristics of the water heater, usually, the power is given for the maximum allowable operating temperature; if the coolant is cooler, then the actual power will be lower.

Maximum water temperature

The highest water temperature provided by the device. The standard temperature of hot water in the water supply is 60 °C, and this value is actually the minimum for modern water heaters: models with more modest rates (usually from 40 °C) are extremely rare. But higher values \u200b\u200bcan be found much more often: for example, water heaters at 75 °C and 80 °C are very popular, and in the most powerful models in this regard, the temperature can reach 95 °C and even higher.

On the one hand, strong heating requires appropriate power (which is especially noticeable in the case of instantaneous electric heaters). On the other hand, the higher the temperature of hot water, the less it is needed for a comfortable outlet temperature, after mixing with cold water; this reduces the consumption of heated water, which is especially important for storage boilers. In addition, many models have their own thermostat (see "Functions").

Also note that heating to operating values may involve different Δt (degree of temperature change) — depending on the initial temperature of the cold water. And the actual performance of the heater directly depends on Δt; this moment is described in more detail below, in the paragraphs devoted to performance at different Δt.

Performance (Δt ~25 °C)

Water heater performance when heating water by approximately 25 °C above the initial temperature.

Productivity is the maximum amount of hot water that the unit can produce in a minute. It depends not only on the power of the heater as such, but also on how much water needs to be heated: the higher the temperature difference (Δt — “delta te”) between cold and heated water, the more energy is required for heating and the smaller the volume of water with which the unit can handle in this mode. Therefore, the performance of water heaters must be indicated for specific options Δt — namely 25 °C, 40 °C and/or 50 °C. And it is worth choosing according to this indicator taking into account the real needs for hot water: exactly how much and what temperature is needed for a particular situation. Methods of such calculations can be found in special sources.

Recall that water begins to be felt by a person as warm somewhere from 40 °C, as hot — somewhere from 50 °C, and the temperature of hot water in central water supply systems (according to official standards) is at least 60 °C. Thus, at Δt~25°C, for heating to at least the same 40°C, the initial water temperature must be at least 15°C (15+25=40°C). This is a rather high value — for example, in a centralized water supply system, cold water reaches 15 °C, except in summer, when the water pipes warm up noticeably; the same applies to water supplied from wells. So in fact, in the “Δt ~ 25 °C” mode, modern water heaters...work quite rarely — either if the initial water temperature is high enough, or if it does not need to be heated much. Most often, the degree of heating is much higher, and the performance is lower. Nevertheless, data for a given degree of heating is still often given in the characteristics — including for advertising purposes, since with a low Δt, the performance figures are quite impressive. In addition, this information can be useful in fact — for the situations mentioned above, when heating by 25 °C is quite enough.

Performance (Δt ~40 °C)

Water heater performance when heating water by approximately 40 °C above the initial temperature.

Productivity is the maximum amount of hot water that the unit can produce in a minute. It depends not only on the power of the heater as such, but also on how much water needs to be heated: the higher the temperature difference (Δt — “delta te”) between cold and heated water, the more energy is required for heating and the smaller the volume of water with which the unit can handle in this mode. Therefore, the performance of water heaters must be indicated for specific options Δt — namely 25 °C, 40 °C and/or 50 °C. And it is worth choosing according to this indicator taking into account the real needs for hot water: exactly how much and what temperature is needed for a particular situation. Methods of such calculations can be found in special sources.

Recall that water begins to be felt by a person as warm somewhere from 40 °C, as hot — somewhere from 50 °C, and the temperature of hot water in central water supply systems (according to official standards) is at least 60 °C. Thus, Δt ~ 40 °C is a rather significant degree of heating: at an initial temperature of about zero, it allows you to warm the water to the “warm” state, and at an initial temperature of 10 °C — to the “hot” state (10 + 40=50 °C). However in order to achieve standard operating temperatures (60 °C or more), the heater most often has to work with a higher Δt — and, accordingly, with a lower pe...rformance. However, the performance data of the device in the “Δt~40 °C” mode, although not perfect, nevertheless accurately describes its real capabilities.

Performance (Δt ~50 °C)

Water heater performance when heating water by approximately 50 °C above the initial temperature.

Productivity is the maximum amount of hot water that the unit can produce in a minute. It depends not only on the power of the heater as such, but also on how much water needs to be heated: the higher the temperature difference (Δt — “delta te”) between cold and heated water, the more energy is required for heating and the smaller the volume of water with which the unit can handle in this mode. Therefore, the performance of water heaters must be indicated for specific options Δt — namely 25 °C, 40 °C and/or 50 °C. And it is worth choosing according to this indicator taking into account the real needs for hot water: exactly how much and what temperature is needed for a particular situation. Methods of such calculations can be found in special sources.

Recall that water begins to be felt by a person as warm somewhere from 40 °C, as hot — somewhere from 50 °C, and the temperature of hot water in central water supply systems (according to official standards) is at least 60 °C. Thus, Δt~50 °C can be described as a very significant degree of heating: it allows even water with a temperature of about zero to be heated to the “hot” state, and the level of 60 °C can be reached at an initial temperature of only 10 °C (this temperature, for example, it is quite possible to meet in cold tap water even in the off-season, not to mention the summer). However in modern water h...eaters, operating temperatures above 60 °C are often found; to achieve them, you usually have to work with Δt greater than 50 °C — respectively, and the actual performance is less than indicated in this paragraph. Nevertheless, it is this parameter that is closest to the real capabilities of the water heater when it comes to the full conversion of cold water into hot.

Heat loss

Heat losses arising in the storage water heater due to imperfect thermal insulation of the tank.

No insulating material, even the highest quality, can completely prevent heat from escaping to the outside. This paragraph just indicates the amount of heat that “leaks” through the thermal insulation of the boiler per day; to maintain the temperature, this leakage must be compensated by additional heating, even if no water is consumed. So from a practical point of view, heat loss is the amount of energy that the heater spends solely on maintaining the temperature of the water inside. Accordingly, the lower this indicator, the more effective the thermal insulation and the more economical the device is in terms of energy consumption. On the other hand, a decrease in heat loss inevitably affects at least the cost, and often also the size and weight of the heater.

Note that this parameter is indicated for standard conditions: a fully filled tank, heated to operating temperature, zero water flow and a certain outdoor temperature (usually about 20 °C). Under other conditions, the actual level of heat loss may differ from the claimed one in one direction or another. Nevertheless, according to this characteristic, it is quite possible to compare different models directly: lower heat losses claimed by the manufacturer will in fact mean more economical energy consumption.


Heater efficiency.

Recall that in a general sense, efficiency is the ratio (in percent) between useful work and total energy consumed. And in water heaters, this parameter is indicated mainly for gas models of a flow-through design. It describes what part of the heat from the gas burning in the furnace is transferred to the water; accordingly, the higher the efficiency — the more efficient this model, the less gas it will need to heat a certain volume of water to a certain temperature. However the increase in efficiency inevitably affects the price of the device; on the other hand, additional spending can quickly pay off due to gas savings.

In general, modern gas "flows" have fairly high efficiency — from 81 – 84% in the most modest models to 90% or more in the most efficient ones.

Tank lining

Enamel. Like plastic, enamel is chemically neutral and does not affect the taste and smell of water, while it is considered more durable and durable. Theoretically, this material is prone to the appearance of microcracks, including due to temperature differences (which eventually leads to water contact with metal and corrosion). However, in fact, high-quality heat-resistant enamels are most often used in boilers, which have the same coefficient of thermal expansion as the material of the tank, and are damaged only in case of violation of operating conditions (or with strong impacts) .. So the mentioned drawback is typical mainly for the most inexpensive models with appropriate quality materials.

Stainless steel. Due to its high strength, stainless steel is considered the most reliable and durable material today. Unlike enameled ones, such tanks are absolutely not afraid of temperature changes, and they also normally withstand shocks and shocks, including pretty strong. On the other hand, steel is noticeably more expensive than enamel. At the same time, for such containers, the possibility of corrosion is not ruled out — especially when it comes to cheap devices that use outdated welding technologies, and the material of the seams may differ from the material of the tank. To eliminate this phenomenon, cathodic protection is required, which further affects the cost.

Glass ceramics. Material, in many respects similar to the enamel described above. On the one hand, glass-ceramic does not react with water, does not affect its taste and properties, and is also considered quite reliable. On the other hand, this material is more brittle and prone to the appearance of microcracks and the loss of its properties — both as it wears out and due to strong heating. Because of this, such water heaters usually have a recommended temperature limit of 60 °C.

Plastic. Plastic is chemically resistant, not subject to corrosion and practically does not affect the composition of water, besides it is inexpensive. The main disadvantage of plastic coating is considered to be fragility.

— Copper. Copper coating is used exclusively in instantaneous water heaters (see "Type"); more precisely, in such devices, the entire tank is usually made of copper. This material is not suitable for a storage tank: copper is too heavy, besides it has a corrosive effect on some materials (aluminium, cast iron) due to its electrochemical properties, even if these materials are used outside the heater, in other parts of the water supply system. However, in a small tank in an instantaneous water heater, these moments are invisible, while copper perfectly tolerates compression and tension during temperature changes.

— Titanium-cobalt alloy. A special alloy, characterized by the highest strength and resistance to corrosion, but also very expensive. It is extremely rare, only in top-level heaters.

Water supply

Under pressure. Such water heaters are designed for a constant pressure of about 6 atmospheres, due to which they can be connected directly to the water supply and wired to several water points (for example, a washbasin and a shower in the bathroom and a kitchen sink). Note that, by definition, all boilers are designed for this format of work, that is, storage models (see "Type"), as well as the vast majority of flow heaters.

Without pressure. Such water heaters do not imply direct connection to the water supply and constant operation under high pressure. The non-pressure principle of operation is found exclusively in flow models; such devices can be divided into two main categories. The first is separately made heaters that are connected to the water supply through a tap or other similar device; so to supply water to the heater, you must first open the tap. The second option is models that themselves are made in the form of water taps (see "Body shape"). Anyway, non-pressure devices cannot serve more than one draw-off point.

Heating time

Time to heat up a storage tank (see "Type"), completely filled with cold water, to operating temperature.

It is worth remembering that this characteristic is not 100% accurate. Manufacturers usually indicate the heating time for certain conditions: a completely filled tank, maximum heating intensity, temperature rise (∆t) by a certain number of degrees. In fact, the heating time may differ, both in one direction and in the other. For example, if a device is claimed to have a heating time of 20 minutes at ∆t = 50 °C, then when water is heated from 15 °C to 60 °C, the time will be shorter (∆t = 45 °C). Nevertheless, this indicator makes it possible to evaluate the overall performance of the boiler, and with equal ∆t and volumes, different models can be compared in terms of heating time.

Magnesium anode

Magnesium anode is used in storage heaters (see type). It is an additional means of protecting the tank and heating elements from corrosion. Due to its special electrochemical properties, magnesium significantly slows down the oxidation of other metal parts that come into contact with water. Note that the magnesium anode has a limited service life — it needs to be changed every 5-7 years.

Electronic anode

A fundamentally new version of protection for the heating element and the internal surfaces of the tank. Thanks to the electronic anode, the potential difference between the heating element and the tank is leveled, which neutralizes corrosive currents. The electronic anode consists of two titanium plates between which a constant voltage of about 0.5 V is passed. The voltage source is a built-in battery pack or voltage converter. Unlike magnesium anodes, which simply dissolve during the protection of the water heater, the electronic anode is not subject to wear and therefore does not need to be serviced.

Heating elements

The number of individual heating elements provided in the design of the water heater. In this case, it is the total number of elements that is taken into account, regardless of whether they belong to the same type or to different ones: for example, 2 heat exchangers and 1 heating element are considered as 3 elements.

All gas models (see "Power source") have only one heating element — this is quite enough for efficient operation. In combined devices (see ibid.), on the contrary, there are several heating elements by definition (at least two — a heat exchanger and an electric one). In electric and indirect water heaters, the options may be different.

The meaning of several heaters of the same type is primarily to increase the heating efficiency. For example, in a flow-through (see "Type") electrical device, in this way it is possible to increase the working length — the distance that water passes inside the device from inlet to outlet; by increasing the working length, the water is heated longer. In storage electric models, several heaters provide more uniform heating of the water, and in indirect ones, they allow more heat to be taken away. In addition, in indirect devices, heat exchangers can differ in the source of heating: for example, one can work from a heating boiler, the second from a solar collector.

Also note that duplication of heating elements can also be used as protection against failures: if one of th...em fails, the heating efficiency decreases, but the device remains operational. However, this possibility is not available in all models with several heaters, its presence should be clarified separately.

Heating element type

Spiral. The spiral is made from a high-resistance electrical wire enclosed in a thin insulating sheath. The main advantages of such an element are the heating rate, high efficiency and precise temperature control; in addition, scale is almost not formed on the spiral. And of the shortcomings — a low service life.

"Wet" heating element. TEN (tubular electric heater), is a metal tube with a heating thread laid in the centre; the space between the tube and the thread is filled with an insulating material with good thermal conductivity. Heating elements heat up more slowly than spirals, have a lower efficiency and are prone to the formation of scale on them; on the other hand, their service life is much longer, and in flow heaters, heating elements are not so sensitive to air pockets.

"Dry" heating element. A kind of heating element with an improved design: the heater tube is enclosed in an additional shell (most often made of metal with an enamel coating on the outside) and does not come into contact with water, hence the name. Thanks to this, in particular, the likelihood of scale formation is reduced, which is especially important when working with “hard” water. Also, the replacement of such elements is significantly easier than conventional ones. Among their shortcomings can be called a rather high cost.

Infrared heating element.... Tubular electric heater of a special design: in the form of a transparent glass tube, in which the incandescent spiral is enclosed. The principle of operation of such an element is somewhat different from a conventional heating element: a significant part of the heating is provided by infrared radiation, which heats not so much the water as the walls of the tank — and heat is already transferred from them to the water. Thus, the water is heated not only at the point of contact with the heating element, but also at the point of contact with the walls — which means that the heating is faster and more uniform. Also note that the IR-heater itself is usually "dry"; see above for the advantages of this design. The main disadvantages of such heaters are high cost and relatively short service life.

— Heat exchanger. It is used in gas and indirect heaters (see Energy source). It is a metal structure heated by burning gas (in gas heaters) or passing inside a heated coolant (in indirect heaters). Usually has a ribbed shape; this is done in order to ensure the maximum area of contact with the heated water with relatively small dimensions — the larger this area, the more heat is transferred to the water per unit time and the more efficient the heater works.

Ignition type

The method of ignition of gas in gas water heaters.

— From batteries. Ignition from an electric spark created by a special electrical circuit powered by batteries. Battery ignition allows you to do without unnecessary wires, it can be used in models that do not require a mains connection at all. However the user has to monitor the condition of the batteries and periodically change them, but this does not have to be done so often, and the replacement itself is not difficult.

— From the network. Ignition from an electric spark created by electricity from a socket. Batteries do not need to be changed in such systems, but they require a connection to the mains. Mains ignition is found mainly among gas heaters with advanced electronic control, in which power from the outlet is required for control circuits — it makes sense to power the ignition from the same outlet.

Piezo ignition. Ignition due to a piezoelectric element — a special device that generates electricity when a button is pressed (transforms the mechanical energy of pressing into electrical energy). Piezo ignition does not require battery power, and the life of the piezo element is usually comparable to the life of the heater itself.

Turbine column. It is used in instantaneous water heaters (see "Type"). With this type of ignition, electricity...to create a spark is generated by a microturbine driven by the movement of water through the heater. At the same time, in many cases, no additional actions are required from the user — ignition occurs automatically when the tap is opened and water begins to move through the device.

Note that most gas boilers also allow traditional ignition, from a match or other open flame. This option is provided as a spare, in case of failure of the main ignition system.

Combustion chamber type

Type of combustion chamber of a gas water heater. Combustion chambers are divided into open and closed.

Open (chimney). It works according to the classical scheme: for the combustion of fuel, air is consumed from the room in which the heater is located, and the combustion products are removed through the chimney due to natural draft. For normal operation of such a heater, it is necessary that the room has good ventilation, and the chimney must be at least 4 m high.

Closed (turbocharged). The closed combustion chamber draws air for combustion of the fuel from the outside, and the products of combustion are removed there. In this case, gas exchange is carried out forcibly, with the help of a fan, therefore sometimes such combustion chambers are called turbocharged. The main advantage of such heaters is that they take air for combustion from the street without burning oxygen in the room — thus, comfortable conditions are provided in the room, and the heater itself can be installed regardless of ventilation conditions (for example, in the kitchen or in the bathroom). ). However, for turbocharged chambers, there are restrictions on the maximum length of the chimney.

Chimney diameter

Nominal chimney diameter for which the gas water heater is designed (see "Energy source").

This parameter is useful primarily for the selection and installation of a chimney for a specific device. At the same time, it is worth remembering that the design of the chimney differs depending on the type of combustion chamber (see above). So, for an open chamber, an ordinary pipe is used without any frills; in such cases, one diameter is indicated in the characteristics. But closed (turbocharged) combustion chambers are usually made under the so-called coaxial chimney — a channel of the "pipe in pipe" type, where combustion products are brought out through the inner pipe, and the air necessary for fuel combustion is taken from the outside through the outer pipe. For such chimneys, two diameters are indicated for each of the pipes.


Among the functions of the water heater there are thermostat, automatic water flow regulator, Smart (automatic mode), programmer, display and control via the Internet. More about each of them

— Thermostat. A device that allows you to control the temperature of the water at the outlet of the heater. In accumulative models (see "Type"), the thermostat actually sets the maximum temperature for heating water in the tank; in flow devices, this function is carried out by changing the intensity of heating.

— Automatic water flow regulator. It is used in instantaneous water heaters. Since the water in such devices heats up "on the go", in the process of its movement through the heater, the higher the speed of water movement (the greater the pressure), the lower the heating temperature, and if the pressure is too high, the power of the device may simply not be enough for effective heating. The use of an automatic water flow regulator avoids this — this system regulates the speed of water movement through the heater, limiting it if necessary.

— Smart (automatic mode). A special “smart” mode in which the boiler is controlled (primarily the intensity of heating) automatically. Specific features of this mode may vary depending on the model. However, the followin...g format of operation is most common: during the first week of use, the device remembers at what time of the day the most hot water was used, and then the heater’s operating mode adjusts to this data. Thus, the boiler provides the user with hot water at the right time and at the same time does not waste energy on heating during hours when heating is not needed.

— Programmer. The presence of a programmable thermostat — a device that allows not only to maintain the temperature, but also to program the operation of the device for a certain period of time. The simplest programmers work like a timer, turning on at the right time (vacation or vacation mode, when the device is not active for several days, and when the family returns to the house, it will turn on and heat the water). More advanced ones allow you to set the mode of operation for individual days. Either way, this feature provides added convenience and eliminates the need to constantly adjust the operation of the device manually. On the other hand, the presence of a programmer affects the cost.

— Display. Usually, a simple LCD screen with a few characters is used as a display. However, even such equipment significantly increases the convenience and information content of management. Various service data can be displayed on the display — from the temperature of the water in the tank to messages about malfunctions and failures. This feature slightly increases the cost of the device, but compared to the total cost of the heater, this moment is usually insignificant.

— Management via the Internet. The specific nuances of such control may vary: for example, some models use a special application installed on a smartphone or tablet, while others can work through a regular browser from any computer. However, anyway, this function allows you to control the heater from almost anywhere in the world — provided that there is access to the Internet. In addition, with this control, the user can also monitor the status of the device and receive various notifications (on and off, about the temperature of the water in the tank, about various problems, etc.).


The safety of water heaters can be carried out by such functions as overheating protection, frost protection, protection against switching on without water, protection against voltage drop, electrical protection (RCD), anti- legionella, gas control and draft sensor. More about them:

— Overheat protection. Water heater safety system that automatically turns off the power supply or gas supply (depending on type) when the heating element reaches a critical temperature. This avoids overheating and the troubles associated with it, ranging from heater failure to fire.

— Frost protection. Function to prevent freezing of water in the circuits, tank and/or heat exchanger of the water heater. It will be useful when the device is installed in a room with a low temperature and works with long breaks. Frozen water expands, which can damage the device; to avoid this, the frost protection monitors the temperature of the water in the device and turns on the heating when this temperature drops to a critical level.

— Protection against inclusion without water. A safety system that prevents the heater from being switched on “dry”, that is, without the presence of water in it. Since the heating element...does not transfer heat to the water when turned on, it heats up very quickly and in a short time reaches a high temperature that can lead to damage to the heater and even to a fire. The presence of protection against switching on without water allows you to avoid such unpleasant consequences.

— Voltage surge protection. System for protecting the heater from power surges. Electronically controlled models are usually equipped with such protection (see Control), since it is the control electronics that are most sensitive to problems with the power supply. Note that the capabilities of such systems are noticeably more modest than those of specialized stabilizers or protective systems: the “hardware” of a water heater is able to smooth out relatively weak power surges, but in case of serious failures, it will most likely simply turn off the device to avoid damage. However, this feature anyway will be useful; except that in very unstable electrical networks, prone to frequent fluctuations, such a heater may require an external stabilizer.

— Electrical protection (RCD). Built directly into the heater, the RCD is a residual current device. Such a device is primarily intended to protect people from electric shock — for example, if the insulation is damaged and electricity leaks to the case or into water. When a person comes into contact with this electricity, a so-called leakage current occurs; The RCD reacts to it and almost instantly turns off the power to the boiler, preventing electric shock.
Note that such protective devices are standardly installed directly in switchboards; however, the presence of an RCD in the water heater provides an additional guarantee. It is natural that such equipment is found mainly in electric models.

— Overpressure protection. Safety system that prevents a critical increase in water pressure in the heater. Usually, this protection is based on a safety valve that opens when a certain pressure level is reached and drains excess water, avoiding damage to the heater.

— Gas control. Gas heater safety system that automatically shuts off the gas supply in the event of a burner flame failure. This avoids filling the room with gas and possible unpleasant, and even tragic consequences. Resuming the gas supply after the protection is triggered must be done manually.

— Traction sensor. A sensor that monitors the presence of draft in the chimney of a gas water heater. This function is especially important for models with open combustion chambers: in the absence of draft, combustion products will fill the room where the heater is located. And this, in turn, can lead to a deterioration in people's well-being, health problems and even deaths. To avoid such consequences, this sensor, when detecting problems with traction, turns off the gas supply and issues a warning about the problem. However, such equipment can also be found in individual models with closed combustion chambers — in them, the draft sensor performs mainly a diagnostic function, allowing you to determine what interferes with the normal operation of the burner.

— Antilegionella. A function that prevents the growth of pathogenic bacteria in the cistern and water heater circuits. Some types of such bacteria are able to live and multiply in fairly hot water — up to 60 °C. To avoid this, the Antilegionella system monitors the temperature of the water in the tank and periodically raises it to a level of about 65 °C. The specific methods of operation of such systems can be different: for example, some work strictly according to a set schedule (for example, once every two weeks), others turn on additional heating only if for some period (for example, a month) the water has not been heated to sufficiently high temperatures. . However, "anti-legionella" anyway contributes to hygiene.


Mechanical. Manual control with rotary knobs and mechanical buttons. Models with mechanical control are inexpensive, but the possibilities of the control itself are rather limited and, usually, include only basic functions.

Electronic. Such control is carried out using an electronic unit. Electronically controlled heaters tend to have a wider range of functions than "mechanical" counterparts, may be programmable and equipped with a display to indicate various parameters. On the other hand, ceteris paribus, such heaters are much more expensive.

Governing bodies

Location of heater controls. It is worth choosing by this parameter, taking into account where it is planned to install the device and from which side access to it will be most convenient. For example, when installing in cramped conditions, the water heater can only be opened from the side or from the bottom; for such cases, it is worth looking for a model with the appropriate location of the controls.

Remote control

Possibility to use the remote control with the water heater. The presence of such a remote control in the delivery set should be specified separately, as well as its type — wired, IR or radio; some models support several types of remotes at once, which allows you to choose the option at the discretion of the user.

The convenience of this function is obvious — it allows you to change the operation settings remotely, without going to the device itself. This can be especially useful if the heater is installed in a hard-to-reach place — for example, behind a cabinet or cabinet. On the other hand, the presence of a remote control significantly affects the cost of the unit, and the real need for such control is relatively rare. Therefore, such models of distribution did not receive.

Wi-Fi module connection

The possibility of expanding the capabilities of the water heater by connecting a Wi-Fi module. With its help, control from a smartphone becomes available, diagnostics of the state of the boiler, etc.

Pipe connection

The direction from which pipes are connected to the heater. The choice for this parameter depends primarily on the characteristics of the place where the device is planned to be placed. Note that in universal models (see "Installation"), the place of connection of pipes depends on the method of installation, while specific options in different models may be different, this should be specified separately in each case.

Nozzle tap

The presence of its own tap in the design of the water heater. In such models, the nozzle is attached to the body. This feature is typical mainly for flow type heaters (see above); it allows you to do without buying a separate tap for hot water.

Shower head

Nozzle designed, in accordance with the name, to supply warm water to the shower. It is a complete shower hose with a watering can. Such a watering can differ from a conventional shower in a smaller width of the holes — this is done in order to create sufficient pressure at a low power (and, as a result, productivity) of the water heater.

Shower heads are mainly equipped with flow-through models (see "Type"), but this function is extremely rare in accumulative models: it is assumed that it is more convenient to connect a heater with a tank to a standard mixer in the bathroom.

Conversion to liquefied gas

Possibility of converting a gas water heater to work from liquefied gas (in cylinders).

Recall that by default, all such devices are designed to be connected to the gas main. However, where it would be desirable to have a gas heater (for example, in a house with weak wiring), such a line may not be available. The only option in such cases is the use of liquefied gas in cylinders — and such a gas differs not only in higher pressure, but also in composition (methane is standardly used in highways, propane in cylinders). Therefore, to switch the heater to liquefied gas, it is not enough to install a gearbox — you also need to replace at least the nozzles on the burner, and in some cases, also individual elements of the ignition system. Technically, this feature is available for almost any gas heater; however, if the characteristics directly indicate the possibility of conversion, this usually means that the corresponding parts are immediately supplied with the device. Yes, and their installation is usually much easier than in a device where re-equipment is not initially provided.

Tank Manufacturer's warranty

The warranty period claimed by the manufacturer for the storage tank (see "Type").

This parameter is important for those reasons that in terms of maintenance, the tank is the most difficult element: other parts of the water heater are relatively easy to repair and change, and in case of problems with the tank, it is often easier to replace the entire boiler. In the most advanced models, the tank warranty can be 10 years or more.


The weight of the device itself, excluding the water collected (passing) into it.
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