what is meant by condensing boiler
what is meant by condensing boiler
Considering 100 the heat of the flame delivered by a conventional boiler, this is able to recover about 90%. the rest is dispersed into the atmosphere via the exhaust fumes at a temperature above 140/160° C. Furthermore, as shown in the figure, they also contain a large amount of heat in the form of water vapour, which is a product of combustion.
A condensing boiler is able to recover the heat emitted in the form of water vapour.
Its heat exchanger is specifically designed to appropriately lower the temperature of the exhaust fumes and obtain condensation of the water vapour, which occurs around 55°C .
The heat released by the condensation is transferred to the system, which therefore will have to absorb less heat to reach the flow temperature, thus saving on gas consumption.
this heat of condensation of methane gas is about 11% of its total thermal energy, therefore the amount of savings is considerable. in fact, a further 11% is added to the heat supplied by the gas boiler (100%) due to the recovery of the condensation heat.
To make the most of the condensation , a low temperature is required in the heating circuit as the system return is capable of "cooling the fumes".
However, the maximum temperatures in the heating circuit should not exceed 75°/55°C (corresponding to the maximum thermal load).
Efficiency measures the efficiency of using the energy contained in the fuel. Theoretically, condensing appliances can reach a maximum efficiency of 111% (referring to the lower calorific value of natural gas, 100+11).
Condensing gas boilers consequently have yields that can reach 107%