Condensing boiler

Condensing boilers are water heaters fueled by gas or oil. They achieve high efficiency (typically greater than 90% on the higher heating value) by using waste heat in flue gases to pre-heat cold water entering the boiler. Water vapour produced during combustion is condensed into liquid form, which leaves the system via a drain. In many countries, the use of condensing boilers is compulsory or encouraged with financial incentives.