gledhill Torrent GreenHeat TGH140-OV Design, Installation & Servicing Instructions page 16

INSTALLATION
Pipe Layout
In all mains pressure installations it is important to remember that the incoming cold
supply must be shared between all terminal fi ttings. It is important that a 22mm supply
is brought to the appliance and a 22mm take-off is continued at least to the bath. If
there are two baths, 28mm pipework should be considered. One metre of smaller
diameter pipework, or fl ow restrictors, should be provided on the fi nal connection to
all outlets so as to balance the water available. In any event the distribution pipework
should generally be in accordance with EN806:1.
Plastic Pipework
All the recommendations with regard to the heating systems in this manual are
generally based on BS/EN Standard copper pipework and fi ttings. However plastic
pipework system can be used in place of copper as long as:-
a. The chosen system is recommended for use in domestic heating systems by the
manufacturers and it is installed fully in accordance with their recommendations.
b. The design criterion of the plastic system is at least equivalent to the use of BS/EN
Standard copper pipework and fi ttings.
c. Barrier pipework for these systems is recommended.
Ball Valve and Overfl ow
The feed and expansion tank can be fi lled manually if required e.g. using a hose pipe
fi tted with a double check valve.
In this situation an overfl ow pipe can still be fi tted if required to ensure that if a leak occurs
on the plate heat exchanger it can be discharged safely to the outside of the building.
Note: If a ball valve is fi tted, then a warning/overfl ow pipe must always be fi tted.
The feed and expansion tank (provided by the installer) must be sized correctly to enable
the expansion of the entire system volume. This will include the central heating, store,
solid fuel and boiler circuit volumes.
See page 14 for guidance sizing the feed and expansion tank.
Water Treatment
In all Torrent models, the primary (i.e. non-potable) water is stored and the domestic
hot water is heated instantaneously by means of heat exchangers. Therefore treating
the primary water will not contaminate the domestic hot water supply.
Although the Torrent primary store has no special water treatment requirements, the
radiators and other parts of the circuit will require the application of a scale and corrosion
inhibitor. The volumes and concentration should be calculated in accordance with the
manufacturers instructions and when calculating the system volume (i.e. the water
content), the volume of the Torrent should be taken into account.
Use In Hard Water Areas And Scale Protection
The patented design of the domestic hot water heat exchanger is such that the
turbulence through the coil slows down the formation of scale in moderate hard water
conditions. However, the requirements set out in the 'Domestic Building Services
Compliance Guide' and the Building Regulations approved documents L1A and L1B
regarding scale protection should be complied with.
These requirements state that; "where the mains water hardness exceeds 200ppm
provision should be made to treat the feed water to the water heaters and the hot
INSTALLATION
water circuit of combination boilers to reduce
the rate of accumulation of scale". To comply
with this requirement: -
a. The hardness of the mains water should be
checked by the installer and if necessary a
suitable in-line scale inhibitor device should
specifi ed for hardness levels between 200
and 300ppm (mg/l).
b. Where the hardness level is 300ppm (mg/l)
and above, the optional phosphate type
inhibitor should be specifi ed and fi tted at
a suitable point in the cold water supply to
the appliance.
It is important that where the supply to the
Torrent is in 22mm the in-line scale inhibitor
is also 22mm. In practice servicing is not
normally required but in hard water areas, the
requirements can be considered similar to those
needed for instantaneous or 'combi' appliances.
The installation of scale inhibitor should be in
accordance with the manufacturers instructions
and Water Byelaws.
London Loop
As the thermal store gets hot the water will
expand and the water level in the R&E tank
will rise, as will the level of water in the vent
pipe. Hot water will also rise to the top of the
cylinder. When the water at the base of the
cylinder becomes hotter it may run out the cold
feed connection pipe. If the cold feed pipe then
runs vertically it works like chimney with the hot
water rising to the top in the same way hot air
does from a fi re. If this section is not insulated
then it will lose heat and waste energy.
If, however, the cold feed is formed into a
sheppard's crook or london loop it will form a
thermal trap. A thermal trap works by ensuring
that cold water is held below hot water. Because
hot water always rises it will not be able to
move down and around the loop/crook and
therefore will not rise up the cold feed pipe
work. This will reduce heat loss and thereby
prevent energy waste.
The minimum depth of the U trap is calculated
by multiplying the pipe diameter by 8. For
example;
• Using 15mm pipework will require a
minimum of 120mm
• Using 22mm pipework will require a
minimum of 176mm
The use of 22mm pipework will enable quicker
fi lling on initial installation.
Page 16