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Condensing boilers
modern condensing boilers can be over 90%
efficient in their condensing mode. They manage to achieve this
much higher efficiency by making use of the from the normally
wasted flue gas temperature, which is in the region of 175 to
250°C. Extra pipe’s and heat exchanger is take this heat from
the flu and use it to put back into the water entering the
boiler. Since the flue gases are now as low as 75°C the
majority of water vapour in the flu products becomes liquid
giving up its latent heat, hence the term condensing. As a
result of the condensing action there is a weak acid solution
of water which must be discharged from the boiler via a
condensate pipe. The condensate pipe is usually a small plastic
22 mm up hype which extends from the boiler to the nearest
waste point, quite often this is under the sink. Ideally the
condensate pipe should have a continual fall from the point it
leaves the boiler up until the point that connects the waste
pipe. If a constant for he is not possible then that a
condensate pump can be used. The fact that the boiler as a
condensing action this also means that the flu must be
positioned in such a way that the resultant liquid can fall
there down with the flu into the boiler and away through the
condensate pipe.
Boiler installation
London
Most traditional boilers other single
combustion chamber enclosed by the waterways of the heat
exchanger, through which the hot gases can pass and the
eventually expelled from the boiler into the flu at high
temperatures. Condensing boilers on the other hand, are
designed to first allow the heat to rise upwards through a
primary heat exchanger, then at the top of the heater the flue
gases are divided and turned 180° to passed back down over to
secondary heat exchanges the two second dairy heat exchanges
reduce the flow gas temperature to about 55°C, this reduction
of temperature calls as the water vapour, formed during the
combustion of the fuel, to be condensed out the last releasing
the latent heat which would otherwise escape with the move
gases. As the flue gas temperature is reduced the droplets of
water formed for by gravity to collect at the base of the flue
manifold. From here a condensate drying allows the liquid to
run off as described above. Remaining gases are expelled to the
outside environment through a fan assisted balanced flue. The
main point of a condensing boiler is to make the system a lot
more efficient. Older boilers can be as low as 50% efficient
where as modern condensing boilers which are SEDBUK A rated are over 90% efficient.
This means that with old less efficient gas boilers, it is
possible that up to 50% of the gas is being wasted. All new
boilers being fitted by boiler installers are condensing
boilers even if they are attached to older open vented
central heating systems.
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