Comparison Electrolux EWH 100 Formax vs Electrolux EWH 100 Royal

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 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 "Features"). 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. The thermostat, if it is in the design, allows you to change the temperature within a specific mode.

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

— Enamel. Like plastic, enamel is chemically neutral and does not affect the taste and smell of water, while it is considered more durable. Theoretically, this material is prone to the appearance of microcracks, including due to temperature differences (which eventually lead to water contact with metal and corrosion). However, 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 enamelled ones, such tanks are absolutely not afraid of temperature changes, and they also normally withstand hits including pretty strong ones. 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 instant 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, and 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 instant 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.

Time to heat the storage tank (see "Type"), 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 filled tank, maximum heating intensity, and temperature rise (∆T) by a certain number of degrees. In practice, the heating time may differ, both one way and the other. For example, if the heating time for the device is 20 minutes at ∆T = 50 °C, then when the water is heated from 15 °C to 60 °C, the time will be shorter (∆T = 45 °C). Nevertheless, this indicator allows us to evaluate the overall flow rate of the boiler, and with equal ∆T and volumes, different models can be compared in terms of heating time.

— Open coil. The open coil 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. Wet 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 open coils, have lower efficiency and are prone to the formation of scale on them; on the other hand, their service life is much longer, and in instant 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, 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. Tu...bular 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 Water heater type). 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. It is done 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 of time and the more efficient the heater is.

The safety of water heaters can be carried out by such functions as overheat protection frost protection, dry heating protection, surge protection, 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 the type) when the heating element reaches a critical temperature. It 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.

— Dry heating protection. A safety system that prevents the heater from being switched on 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 q...uickly 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 can 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 will be useful; except that in very unstable electrical grids, 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 into the case or 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 safety devices are standardly installed directly in switchboards. However, the presence of an RCD in the water heater provides additional security. Naturally, such equipment is found mainly in electric models.

— Safety valve. A 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. It 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.

— Draft sensor. A sensor that monitors the presence of draft in the flue of a gas water heater. This function is especially important for models with open combustion chambers: in the absence of a 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 the draft, turns off the gas supply and issues a warning about the problem. However, such equipment can also be found in 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.

— Anti-legionella. A function that prevents the growth of pathogenic bacteria in the tank and water heater circuits. Some types of such bacteria can live and multiply in fairly hot water — up to 60 °C. To avoid this, the anti-legionella 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.

The warranty period declared by the manufacturer for the storage water heater tank (see “Type”).

This parameter is important for the reasons of maintenance terms. The tank is the most complex element: other parts of the water heater are relatively easy to repair and change, and if there is a problem with the tank, it is often easier to replace the entire boiler. In the most advanced models, the warranty on the tank can be 10 years or more.

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