gledhill Torrent GreenHeat TGH140-OV Design, Installation & Servicing Instructions page 4

DESIGN
Gledhill developed the principal of domestic thermal stores starting in 1982 and
they have been manufacturing them since then.
Their importance to plumbing systems is described below.
a) Why use a thermal store - Alternative energy fuel sources are typically low grade,
inherently unpredictable and are often available in plentiful supply but not when
the heat energy is needed! A thermal store provides the means to harness the
energy when it is available for later conversion into both hot water AND heating.
Being open vented, they provide a simple and inherently safe way to produce high-
performance mains pressure hot water. So the householder can enjoy the comfort
and luxury of a mains pressure system produced from alternative energy sources.
The alternative energy feeds into the thermal store which is also the water that
circulates around the heating system. This means that the energy available from
solar panels or a wood burning stove, for example, can be used to provide energy
into the heating circuit to decrease the use of fossil fuel based boilers, and hence
reduce household running costs.
It is very problematic and inherently unsafe to connect wood burning stoves or
other uncontrolled heat sources to an unvented cylinder, and not easily possible
to combine alternative energy heat sources to provide energy to the heating
circuit, hence the unique advantages of a thermal store.
b) The heart of an alternative energy system - The Torrent GreenHeat is the ideal
product to use as the heart of an alternative energy system as it will take
energy input not only from a conventional boiler but also from a wide variety of
alternative energy sources, including but not limited to:
• solar panels
• wood burning stoves and other uncontrolled heat sources
• ground or air source heat pumps
• electricity from renewable or low carbon sources
If the system is confi gured appropriately the heat from the alternative energy
source will be available for both hot water AND heating. This is only possible with
a thermal store such as the Torrent and is not possible with an unvented cylinder
where you will only get an alternative energy contribution to the hot water.
c) In-built upgrade potential - You are able to specify from the required tappings,
with any future requirements, for example, a wood burning stove or solar panels
can be added as an upgrade to the property at a later stage and the hot water
cylinder will be ready to work with it.
d) Neutral Point - The Torrent GreenHeat becomes the neutral point in any open vented
system because the open vent and cold feed pipes are connected to it. The benefi t
of this is that another device to enable different systems to be joined together at a
neutral point is not required, which would be required in other systems. In multiple
fuel systems, the Torrent acts as a low loss header.
e) Apartments – The Torrent open vented thermal store does not need a discharge pipe
from a pressure and temperature relief valve, unlike an unvented cylinder which does.
This combined with the fact that discharges are not permitted into PVCu soil stacks
makes the installation of un-vented stores in apartments diffi cult and expensive.
f ) Legionella Risk – Alternative energy supplies cannot be relied upon to raise the
temperature of the stored water above 55 every time they operate. This is not a
problem with a thermal store because the store water is not the water that comes
out of the tap. The water that comes out the hot tap is mains cold water run through
a plate heat exchanger on the outside of the thermal store. This water heats very
quickly and the volume of stagnent water in the heat exchanger is very small so
there is virtually no legionella risk.
DESCRIPTION
g) Less controls – The thermal store is open
vented and therefore does not require
additional safety devices such as temperature
and pressure relief valves or an inlet control
group and expansion vessels.
h) Building Regulation – The thermal store,
being open vented, does not require Building
control to be notifi ed to comply with section
G3 of the building regulations, unlike an
unvented cylinder which does.
i) Annual inspection – The running costs of this
cylinder are greatly reduced by not being
required to have an annual safety inspection
where as an unvented cylinder does.
The Torrent provides high performance mains
pressure hot water without the additional costs
incurred with an unvented cylinder.
The Torrent GreenHeat is available in the
following basic variants:-
Torrent GreenHeat OV
The Torrent GreenHeat OV utilises an open
vented boiler and / or direct electric immersion
heaters as its primary energy source. It comes
fi tted with tappings for a woodburning or
solid fuel boiler as standard, but if not required,
can be removed at the time of order.
One of the benefi ts of the open vented boiler
confi guration is that the whole output of
the boiler is available to the thermal store,
unlike the indirect Sealed Primary (SP) version
where the output from the boiler is limited
by the heat exchanger. This will provide an
improvement in the operational effi ciency of
the boiler, reducing the primary energy usage
and running costs.
The Torrent GreenHeat OV provides high-
performance mains pressure hot water. The
heat energy provided from the primary heat
source and / or solid fuel input is circulated
from the store to the central heating circuit,
allowing rapid heat-up of a radiator system.
In situations where no gas or solid fuel source
is available the Torrent GreenHeat OV can be
used exclusively from the two 3kW electric
immersion elements which will provide both
hot water and auxiliary heating for the property.
The obvious application is apartments where
no gas main is available but this could also be
appropriate where electricity is available from
a renewable or low carbon source.
If connected to the standard grid then the
thermal store is the perfect solution to
maximise usage of an off peak tariff where
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