Comparison Marten Praktik MP-20 20 kW vs Ogonek KOTV 16-DG 16 kW

The type of fuel or heater used by the boiler.

— Gas. Gas boilers are popular due to their low fuel cost and several other advantages. For example, heating starts and stops almost instantly, the burner power can be easily adjusted, various additional features can be provided in the design (such as connecting a room thermostat), etc. The disadvantages of this type of boiler are dependence on gas pipelines (gas in cylinders can also be used, but this is rather inconvenient and rarely used), as well as installation complexity and dependence on the power supply.

— Electricity. Boilers with electric heaters are the easiest to install, because of the absence of chimneys, and can have advanced control options. On the other hand, high electricity consumption affects the cost of operation, and only the most low-power models can be connected to a regular outlet — more or less powerful units require a separate connection. Electric boilers are convenient primarily where it is not possible to provide the boiler with gas or solid/liquid fuel.

— Electricity (electrode). A variety of electric boilers (see above), also known as "ionic" ("ion exchange"). The key difference between such devices is that they do not have heating elements or other separate heating elements: heating occurs because the electric current passes directly through the liquid coolant. In...addition to the general advantages of all electric boilers (small size, ease of installation and control, the possibility of using advanced automation, etc.), such models also have such advantages as very high efficiency and good heating rate. It should be noted that even if the water leaks, there is practically no danger of electric shock. On the other hand, electrode boilers are very demanding on the quality of the water: it must be water with a strictly defined salt concentration, and during use, the resulting electrolysis gases must be regularly removed from the heating system and fresh solution added to it. In addition, units of this type, for technical reasons, are not compatible with RCD protection.

— Solid fuel. Solid fuel boilers most often use coal, coke or special fuel briquettes. The main advantage of such boilers is the small price. The disadvantages are due to the type of fuel used: it is most often required to be loaded manually, as well as to remove solid combustion products (ash, soot). In addition, the combustion process is difficult to regulate and cannot be stopped until the fuel is completely burned out, which leads to problems in setting the boiler to the required power and may require special automation. Therefore, such boilers are used where it is impossible to install gas or electric boilers.

— Firewood. Firewood boilers are a type of solid fuel boiler with all their characteristic advantages and disadvantages (see above for details). The main feature of such boilers is that they can use pyrolysis, which significantly increases the efficiency (see Pyrolysis).

— Liquid fuel. Boilers, as the name suggests, use liquid fuel. Most often it is diesel fuel, but some models can also work with lower-quality options — such as fuel oil or even used oil. Such boilers are in many ways similar to gas boilers — in particular, they make it easy to adjust the operating mode and instantly stop heating. At the same time, they are completely autonomous. And they tend to be more powerful. On the other hand, such units require fairly large fuel tanks. Otherwise, you will have to constantly refill the tank during the season, and the fuel itself is much more expensive than gas. In addition, boilers of this type have increased requirements for the quality of the chimney, because, during operation, products of combustion are formed. Another drawback is their high cost. Therefore, liquid fuel models are not widely used; most often they are used as an option for those rooms in which it is impossible to conduct gas.

In addition to single-fuel boilers, there are also combined boilers that can operate with more than one energy source. In modern models, almost any combination is found. For example, gas and liquid fuel, solid fuel and electricity, etc. The exception is perhaps the option "electricity plus liquid fuel", such units are practically not produced. Anyway, compatibility with several energy sources makes the boiler more versatile and less dependent on malfunctions (for example, gas pipeline failures), but it affects its cost. Also note that switching to another energy source may require additional work — for example, replacing a gas burner with a fuel injector.

A very conditional parameter that slightly characterizes the purpose based on the size of the room. And depending on the height of the ceilings, layout, building design and equipment, actual values may differ significantly. However, this item represents the maximum recommended area of the room that the boiler can effectively heat. However, it is worth considering that different buildings have different thermal insulation properties and modern buildings are much “warmer” than 30-year-old and especially 50-year-old houses. Accordingly, this item is more of a reference nature and does not allow us to fully assess the actual heated area. There is a formula by which you can derive the maximum heating area, knowing the useful power of the boiler and the climatic conditions in which it will be used; For more information on this, see "Useful Power". In our case, the heating area is calculated using the formula “boiler power multiplied by 8”, which is approximately equivalent to use in houses that are several decades old.

Long-burning boilers include a specific type of solid fuel model (see "Energy source"). Such boilers have a rather large height with a small width as well as a special air circulation system. Due to all this, not the entire mass of fuel is involved in the combustion process, but only a relatively thin layer (usually about 10 – 15 cm). It means that a lot of fuel can be loaded into the boiler, but it will burn out gradually without generating excessive power and allowing it to work for a long time.

It is the maximum useful power of the boiler.

The ability of the device to heat a room of a particular area directly depends on this parameter; by power, you can approximately determine the heating area, if this parameter is not indicated in the specs. The most general rule says that for a dwelling with a ceiling height of 2.5 – 3 m, at least 100 W of heat power is needed to heat 1 m2 of area. There are also more detailed calculation methods that take into account specific factors: the climatic zone, heat gain from the outside, design features of the heating system, etc.; they are described in detail in special sources. Also note that in dual-circuit boilers (see "Type"), part of the heat generated is used to heat water for the hot water supply; this must be taken into account when evaluating the output power.

It is believed that boilers with a power of more than 30 kW must be installed in separate rooms (boiler rooms).

The type of electrical supply required for normal operation of the boiler. Power supply may be required not only for electric models but also for other types of boilers (see "Power supply") — in particular, for the operation of control automation. Connection options can be:

— 230 V. Work from a household system with a voltage of 230 V. At the same time, models with a power consumption of up to 3.5 kW can be connected to a standard outlet, but for high consumption devices, you need to connect directly to the distribution board. Many of the electric boilers with this connection also allow operation from 400 V (see below).

— 400 V. Operation from a three-phase system with a voltage of 400 V. This power supply is suitable for boilers with any power consumption. However, it is not as common as 230 V: in particular, it may be difficult to use it in a residential area. Therefore, this option is provided mainly in high-power devices for which a 230 V power supply is not suitable.

— Autonomous work. Work in completely autonomous mode, without an electricity connection. This format of operation is found in all boilers that do not use electrical heating (see "Energy source"), except for purely liquid fuel ones — in them, electricity is necessary for the operation of the fuel supply systems.

The maximum electrical power consumed by the boiler during operation. For non-electric models (see Energy source), this power is usually low, as it is required mainly for control circuits and it can be ignored. Regarding electric boilers, it is worth noting that the power consumption in them is most often somewhat higher than the useful one since part of the energy is inevitably dissipated and not used for heating. Accordingly, the ratio of useful and consumed power can be used to evaluate the efficiency of such a boiler.

The minimum operating temperature of the heat medium in the boiler system when operating in heating mode.

The maximum operating temperature of the heat medium in the boiler system when operating in heating mode.

The maximum pressure in the heating circuit of the boiler, at which it remains operational, and there is no risk of physical damage to the structure. For a heating system, the maximum pressure is usually about 3 bar, and for a domestic hot water circuit up to 10 bar. When the maximum pressure is exceeded, a safety valve is activated, and part of the water is discharged from the system until a normal pressure level is reached.