gledhill Torrent GreenHeat OV TGH140 Design, Installation & Servicing Instructions page 3

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 configured 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 benefit
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 difficult and expensive.
f ) Legionella Risk – Alternative energy supplies cannot be relied upon to raise the
temperature of the stored water above 60 degrees 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 notified 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 is
available with tappings for a woodburning
or solid fuel boiler, but if any of the standard
tapping are not required, they can be removed
at the time of order.
One of the benefits of the open vented boiler
configuration 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 efficiency 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 arrangements
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should be made to power the lower immersion element in order to minimise the running
costs. It is important to note that the design heat loss, of the rooms to be heated, must
be less than the lowest immersion power. If the design heat loss is greater than this, the
heating will need to be supplemented by another heat source.
The Torrent GreenHeat OV is designed to be heated directly (i.e. without internal heat
exchangers) by one or more of the following heat sources;
• Electric immersion heaters e.g. to utilise off peak electricity
• A remote gas or oil boiler
• A solid fuel boiler or stove
Torrent GreenHeat SP
The Torrent GreenHeat SP utilises a sealed system boiler as its primary energy source.
It is available with tappings for a woodburning or solid fuel boiler, but if any of the
standard tapping are not required, they can be removed at the time of order. The
Torrent GreenHeat SP provides high-performance mains pressure hot water.
Where a sealed primary coil is used, the thermal store is a hot water only thermal store.
If too much heat is taken out of store, then hot water performance will be limited. The
hot water priority should be protected by use of an appropriate thermostat. The central
heating circuit is normally supplied directly from the boiler although an auxiliary
heating circuit can be connected from the store in which case the solid fuel source
will provide energy to the auxiliary heating circuit. Obviously, the energy output that
can be provided by the auxiliary heating circuit will be limited to the energy input
from the solid fuel appliance.
This sealed primary (SP) model permits the use of a smaller feed and expansion tank
because the main central heating circuit does not need to be catered for. This can
make positioning the F&E tank more straightforward.
An immersion element is provided and it is normally envisaged that this will be used as an
emergency electric back-up for hot water and to provide emergency energy to the auxiliary
heating circuit. However, if a low carbon or renewable electricity source is available then
this could be connected to the immersion element to provide heat input to the thermal
store, decreasing the use of the fossil fuel boiler and hence reducing running costs.
The Torrent GreenHeat SP is designed to be heated by one or more of the following
heat sources;
• Directly by an electric immersion heater as a backup heat source only
• Indirectly (i.e. via a heat exchanger) by a remote gas or oil boiler
• Directly by a solid fuel boiler or stove
Torrent GreenHeat SOL
The Torrent GreenHeat SOL utilises either a sealed system boiler and / or an open
vented boiler as its primary energy source. It also has a high-efficiency solar coil to
allow the homeowner to benefit from a wide variety of alternative energy inputs.
It is available with tappings for a woodburning or solid fuel boiler, but if any of the
standard tapping are not required, they can be removed at the time of order.
The Torrent GreenHeat SOL provides high-performance mains pressure hot water.The
central heating circuit can be supplied directly from a sealed system boiler although
an auxiliary heating circuit can be connected from the store in which case both the
solar and solid fuel energy will also provide an input to the auxiliary heating circuit.
Alternatively, an open vented boiler can be used to directly heat the store so that the
energy will be available for both hot water and auxiliary central heating circuit.
The cylinder comes with two return connections for solid fuel and woodburning
stoves to enable the homeowner to have an aga running 24 hours a day but still
retaining the dedicated solar volume.
An immersion element is provided and it is normally envisaged that this will be
DESIGN
used as an emergency electric back-up for
hot water and to provide emergency energy
to the auxiliary heating circuit. However, if a
low carbon or renewable electricity source is
available then this could be connected to the
immersion element to provide heat input to the
thermal store, decreasing the use of the fossil
fuel boiler and hence reducing running costs.
The Torrent GreenHeat SOL is designed to be
heated by one or more of the following heat
sources;
• Directly by an electric immersion heater as
a backup heat source only
• Either indirectly or directly by a remote gas
or oil boiler
• Directly by a solid fuel boiler or stove
• Indirectly by solar thermal system
Torrent GreenHeat HP Models
The Torrent GreenHeat HP and HP SOL are
directly heated, open vented thermal stores
designed for use with an air source or a ground
source heat pump. It is available with tappings
for a woodburning or solid fuel boiler, but if any
of the standard tapping are not required, they
can be removed at the time of order.
Although the thermal store is open vented,
the mains pressure hot water is heated
instantaneously via the plate heat exchanger.
The Torrent GreenHeat HP range of primary
thermal stores are only suitable for open
vented heating systems but they provide mains
pressure hot water without the requirements of
a pressure and temperature relief valve.
The suggested model sizes are based on typical
hot water usage and the store charged to about
75°C. If the store charge temperature is going
to be lower, then a larger model should be
considered. This is especially important where
the heat pump alone is unable to charge the
store to 75°C as is likely to be the case with a
heat pump. If the immersion element is used
to raise the temperature of the store, then
a suitable control system should be used
to ensure the immersion element does not
operate until the heat pump has raised the store
to the maximum temperature, or the overall
efficiency of the system will be reduced.
The Torrent GreenHeat HP and HP SOL is
designed to be heated by one or more of the
following heat sources;
• Directly by a ground source or air source heat
pump
• Directly by an electric immersion heater as
a backup heat source only
• Directly by a solid fuel boiler or stove
• Indirectly by solar thermal system
DESCRIPTION
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