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An 'indirect' cylinder is
designed to be heated by a remote heat source. The typical
modern gas boiler produces a pumped circuit of hot water that
will heat both cylinder and radiators. There are however devices
that can produce a circuit of hot water that is unpumped, relying
instead on 'gravity circulation' to do the job. It is important to
match the type of cylinder to the heat source - pumped (as it would be
from a typical gas boiler) or unpumped (the sort of heat source
one might expect to get from a solid fuel or wood burning stove, an AGA or
Rayburn stove). The cylinder should also be a vented type*.
* Note:
Unvented cylinders (the type that provide mains pressure hot
water - e.g. Megaflo, Stainless Lite) should not be connected to a heat source that cannot be
fully controlled - the risk of explosion exists. Mains pressure
hot water can however be achieved in conjunction with a gravity
heat source by using a storage device such as a
Thermal Store or a
Torrent Multifuel. For more
info please click on the links or feel free to
contact our office.
How an AGA cylinder differs
An AGA (for example) will produce
an 'unpumped' circuit of hot water relying on the
principle of hot water rising (and cooler water falling) to
create 'gravity circulation' within the system. A cylinder that
will happily accept an unpumped heat source is subtly different
from a standard cylinder in so far as the heat exchanger has a
larger diameter bore (28mm) and bigger tappings (the in and out
connections) which are spaced slightly wider apart improving the
thermal dynamics and therefore the flow.
Choose the correct cylinder for
AGA, Rayburn and Wood burning stoves
Do not connect a cylinder designed
for a fully pumped system to an unpumped system. The smaller
bore heat exchanger in a cylinder suitable only for a pumped
system would constrict the flow of a gravity system. This could
have significant implications as heat dissipation becomes strangled. Please ensure
you mention the heat source/s you intend to connect when
ordering to ensure you get the right advice and the correct
product. |
