Heating area
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.
Heat output
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).
Heating circuit max. pressure
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.
Efficiency
The efficiency of the boiler.
For electric models (see "Energy source"), this parameter is calculated as the ratio of net power to consumed; in such models, indicators of 98 – 99% are not uncommon. For other boilers, the efficiency is the ratio of the amount of heat directly transferred to the water to the total heat amount released during combustion. In such devices, the efficiency is lower than in electric ones; for them, a parameter of more than 90% is considered good. An exception is gas condensing boilers (see the relevant paragraph), where the efficiency can even be higher than 100%. There is no violation of the laws of physics here. It is a kind of advertising trick: when calculating the efficiency, an inaccurate method is used that does not take into account the energy spent on the formation of water vapour. Nevertheless, formally everything is correct: the boiler gives out more thermal energy to the water than is released during the combustion of fuel since condensation energy is added to the combustion energy.
Flue diameter
The diameter of the pipe through which combustion products are discharged from the combustion chamber.
In boilers with a closed combustion chamber often used the coaxial flue, consisting of two pipes nested one inside the other. At the same time, products of combustion are discharged from the combustion chamber through the inner pipe, and the air is supplied through the gap between the inner and outer ones. For such flues, the diameter is usually shown in the form of two numbers — the diameter of the inner and outer pipes, respectively. The most popular values are
60/100,
80/80 and
80/125. Non-coaxial flues can be
100,
110,
125,
130,
140,
150,
160,
180 and
200 mm.
Inlet gas pressure
It is the optimum gas pressure supplied to the inlet of the boiler system. Most often indicated for natural gas and is about 15-20 mbar. This parameter must match the specs of the gas supply system. However, the pressure in the latter may be higher, which may require the installation of a special gas regulator.
Max. gas consumption
Maximum gas consumption in the boiler with the corresponding energy source (see above). Achieved when the gas heater is operating at full capacity; with reduced power and consumption, respectively, will be lower.
Note that boilers of the same power may differ in gas consumption due to the difference in efficiency. While the more fuel-efficient models tend to cost more, the price difference pays off in gas savings.
Safety systems
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Gas pressure drop. This protection system ensures that the boiler is switched off in the event of a critical drop in gas pressure, insufficient for the normal functioning of the burner. In the event of such a fall, the valve that supplies gas to the burner is closed and blocked. After the restoration of gas pressure, it also remains closed; it is necessary to open it and resume the gas supply manually.
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Water overheating. A temperature sensor automatically turns off the boiler when the temperature of the water in the system is critically exceeded.
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Flame loss. Flame loss protection is based on a sensor that monitors the combustion of gas and automatically stops its supply. It prevents the room from filling with gas and the possible tragic consequences of this.
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Draft control. In boilers with an open combustion chamber, to maintain normal conditions in the room where such a boiler is installed, constant removal of products of combustion into the atmosphere is necessary. The lack of a normal draft in the chimney can lead to the accumulation of combustion products in the room. The draft protection system prevents this by automatically turning off the boiler when it detects the release of combustion products outside the chimney.
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Power outage. Most modern boilers h
...ave an electronic control system; in addition, many structural elements (pumps, valves, fans, etc.) are also powered by electricity. Thus, a power outage during the operation of the boiler will inevitably lead to an abnormal mode of operation, which is fraught with breakdowns and even accidents. To prevent such cases, a power outage protection system is installed, which completely stops the operation of the boiler in the event of a power outage. When the power supply is restored, the boiler needs to be restarted manually.
— Water circulation failure. This protection system controls the normal movement of the water through the heating circuit. Water circulation failure can lead to overheating of some elements of the boiler and damage to it. To avoid this, if the circulation is disturbed, the system turns off the pump and shuts off the gas supply to the burner.
— Frost protection. A system that controls the temperature in the heating circuit. Freezing of the liquid in the circuit disrupts the normal operation of the heating, which may require heating of the pipes and lead to system damage. To avoid this, when the water temperature drops below 5 °C, the burner is ignited, the circulation pump is activated, and the circuit warms up to a temperature of about 35 °C — thus preventing the formation of ice in the pipes.
