Power consumption
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.
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.
Combustion chamber
The type of combustion chamber provided in the boiler.
—
Open(atmospheric). Combustion chambers of this type consume air from the room in which the boiler is installed, and the combustion products are naturally removed through the flue. Boilers of this design are simple and inexpensive but have specific installation requirements: the room must be well-ventilated, and the height of the chimney must be at least 4 m to ensure sufficient draft.
—
Closed(turbocharged). Closed combustion chambers are isolated from the room in which the boiler is installed: combustion air is taken from the street, and combustion products are removed there. For this, a coaxial flue is usually used — in the form of two pipes nested one inside the other: combustion products are removed through the inner one, and the outer one is responsible for the air supply. Turbocharged combustion chambers are more complicated and expensive than open ones, and the maximum length of the chimney is limited. On the other hand, such a boiler does not burn the air in the room, and it can be installed anywhere, regardless of the ventilation efficiency.
— Is absent. Boilers powered by electricity do not have combustion chambers (see "Source of 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.
