Condensing boiler  From Wikipedia, the free encyclopedia Jump
to: navigation, search  Condensing boilers are water heaters in
which a high efficiency (typically greater than 90% on the
higher heating value) is achieved by using the waste heat in the
flue gases to pre-heat the cold water entering the boiler. They
may be fuelled by gas or oil and are called condensing boilers
because the water vapour produced during combustion is condensed
into water, which leaves the system via a drain. In many
countries their use is compulsory or encouraged with financial
incentives.  Principles of work[edit]  In a conventional boiler,
fuel is burned and the hot gases produced are passed through a
heat exchanger where much of their heat is transferred to water,
thus raising the water's temperature.  One of the hot gases
produced in the combustion process is water vapour (steam),
which arises from burning the hydrogen content of the fuel. A
condensing boiler extracts additional heat from the waste gases
by condensing this wate