How efficient is your condensing boiler?

Use this calculator to estimate the mean boiler efficiency of a condensing boiler system given a return water temperature and percent load at different time intervals.

Unit Type

Operation Profile
i
Hours running
Boiler Load % of rated capacity
25
50
75
100

Return Water Temperature °C

0%
0%

Did you know?

Condensing boilers are capable of achieving thermal efficiencies as high as 98%. However, their performance is highly influenced by two main factors: the return water temperature and the system's operating load.

As a general rule, maintaining return water temperatures around 50°C or lower is necessary to achieve true condensing efficiencies. Additionally, operating the system at part load—rather than full load—can further enhance efficiency by allowing more heat recovery from the exhaust gases.