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.
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.