Condensing boilers are
distinguished by greater efficiency than conventional ones, thanks to which
their operation is cheaper.What is the difference?
Conventional boilers, ie
non-condensing boilers, burning fuel do not use part of its energy called
latent heat to heat the water flowing through it. Its release occurs at the moment of
condensation of water vapor present in the combustion products, and for this to
happen, they must be cooled to a temperature lower than the so-called dew
point, about 56oC for natural gas, 52oC for liquid gas and 47oC for oil
firewood. Conventional boilers
are not adapted to condensation - their control systems do not allow it. Condensing boilers have heat
exchangers designed to make it possible without harm to them (they are
resistant to acid) and without interference in their operation (low temperature
of flue gas is synonymous with a poor chimney draft, therefore it must be
supported by a fan).
The amount of latent
heat in a fuel depends on its water content - for natural gas it is an
additional 11%, for propane 9% and for fuel oil 6% of energy. Hence, the theoretically feasible
efficiency achieved by boilers related to the calorific value (in accordance
with the standards adopted in Europe) is 111%,
109% and 106% respectively. In
practice, condensing boilers reach efficiency by 2-4% lower, due to heat loss
and incomplete combustion - it is by a dozen or so percent more than
conventional ones, and this translates into lower fuel consumption by several
percent.
