Comparison Electrolux EWH 50 Royal vs Bosch Therm 4000 O WR 10-2 P

In addition to the classic, familiar to all storage heaters and gas water heaters, you can find tankless wall-mounted water heaters, instant taps and boiling systems.

— Tankless. Tankless 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 storage heaters, 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, and 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 a tankless 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 tankless water heaters. However, their efficiency, respectively, will be lower. Nevertheless, gas heaters are deprived of these shortcomings (see "Energy source") — in general, it is not difficult for them to provide the necessary power.

— S...torage. Water heaters are equipped with a water tank; cold water is drawn into this tank, heated and 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 tankless heaters (and the larger the water supply, the larger and more expensive the device), and their energy consumption is generally somewhat higher, 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 tankless 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 tankless models this moment 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 (except for the mandatory presence of a power supply) and instant taps (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 have such a name, is the ability to heat water to 100 °C, thereby several litres 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 catalogue in the taps section.

— Instant tap. tankless 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.

— 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 flue gasket to remove combustion products. At the same time, the mentioned high power is relevant mainly for gas water heaters (instant water heaters), and most gas models belong to this type. However, there are also storage gas water heaters.

— Mains. Electric water heaters are versatile and easy to install — unlike gas, and they do not need a flue. 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 switchboard 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 storage 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 for storage (see "Type") — t...his 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.

— 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. 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.

The volume of the tank installed in the storage water heater (see "Type"). It 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 this point of view determining the optimal capacity of the tank.

Some special tables and formulas 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 litres; 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 value is considered to be a volume of 80 – 100 litres, such a tank is quite enough for an apartment in which 3 – 4 people live. In the largest models, the volume is already calculated in cubic metres; such water he...aters 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.

The shape of the water heater.

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

— Cylindrical. This form is traditional for storage water heaters. It is because with the same total volume, less material is needed for a cylindrical tank than for a rectangular one; and in production, such tanks are simple and cheap, which allows them to be used in water heaters 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. It is the traditional form for instant 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 instant water heaters, the “rectangle” is simply one of the most convenient options in terms of the overall layout. But in storage water heaters, this shape differs from the flat one (see below) only with a slightly greater thickness and, in some cases, pronounced angles.

— Flat. A variant found mainly in s...torage 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 bathroom, where a cylindrical device would hang over the toilet bowl, creating discomfort.

— Slim. A variety of cylindrical cases are 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.

The type of power required to operate the water heater.

— 230 V (1 phase). Powered by a single-phase household main 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, 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 a three-phase main at 400 V. This power format can be called "industrial", connection to 400 V is available in specialized boiler rooms, workshops and other similar places, but in an ordinary residential area it may be difficult — you will likely 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. 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- Energy independent. Water heaters that operate without power at all and do not require an electrical connection. Only gas a...nd indirect models can be energy-independent (see “Energy source”). However, not every gas or indirect heater belongs to this category.

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.

Electrical power consumed by the heater during operation.

This parameter is of key importance for electric models (see "Energy source"). In them, the power consumption corresponds to the power of the heating element and, accordingly, the heat output of the entire device. The overall efficiency and flow rate of the water heater directly depend on the useful power. Accordingly, high-flow rate 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 flow rate and water temperature. So when choosing a device according to flow rate, you need to look primarily at flow rate and temperature. Power must be taken into account when connecting: for example, if a 220 V model (see "Power source") consumes more than 3.5 kW, it, as a rule, cannot be plugged into a regular outlet — connection is required according to special rules. And the most productive and high-powered models — 10 kW or more — are connected only to three-phase mains.

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. 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.

Rated power of the heat exchanger installed in the gas or indirect heater (see "Water heater type"), 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.

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 can be found much more often: for example, water heaters of 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 instant 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 thermostats (see "Features").

Also, note that heating to operating values may involve different ΔT (degree of temperature change) — depending on the initial temperature of the cold water. 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.