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4 INSTALLATION
4.1 Cylinder Location
The unit must be located where it can be supplied from an expansion tank / cistern above the
cylinder. A vertical vent pipe of at least 19mm internal diameter must be connected to the hot
outlet.
Ensure the cylinder is positioned such that future servicing and part replacement is possible.
The routing of pipework must not prevent the thermostats or immersion heater from being
removed for maintenance.
4.2 Hot & Cold Water Connections
All connections to the cylinder must be made using compression fittings. We recommend 22mm
supply pipework is used.
4.2.1 Drain
A full bore drain cock (not supplied) must be fitted to the cold inlet pipework, between the cistern
and the cylinder, at as low a level as possible, to facilitate draining.
4.2.2 Distribution pipework
The pipework supplying the hot water taps should be run in 22mm throughout the property.
Only short lengths (max 1 metre) of 15mm should be used to connect baths, showers and basin
taps where required. If using a secondary / pumped return circuit, all pipework must be well
insulated. The circulator (bronze pump) should be time and/or temperature controlled to reduce
energy consumption.
4.3 Primary, Renewable & Tertiary Circuits
The working pressure and temperature for all heat exchanger coils must not exceed 6 bar and
120°C respectively. All connection to the cylinder must be made using compression fittings.
All 22mm coils
must be fully pumped
– gravity circulation is NOT suitable for the 22mm coils.
Gravity circulation may be used on the 28mm coil(s) only, although these may be pumped if
desired.
4.3.1 Safety thermostat
Each heat exchanger coil has an associated combined control & safety thermostat. These can
be used as part of system controls on
fully pumped circuits only
. Suggested S-Plan and Y-
plan system schematics are given in Section 4.5.
Controls devises (e.g. motorised valves)
must not be used on gravity circuits
.
4.3.2 Solar installations
If connecting a solar thermal installation, for example, to the renewable coil, the controls must
be wired in series with the combined control & safety thermostat. If using a solar pump station
with check valves to prevent gravity circulation, a motorised valve may not be required. Refer to
the appliance manufacturer’s instructions and to Building Control for further guidance.
Additional motorised valves (not supplied) may be required.
4.4 Hard water
In areas with moderately hard water, choosing a lower control thermostat temperature can result
in less scale being deposited within the cylinder. Where water hardness in excess of
200mg/litre is experienced, a suitable and effective hard water treatment must be installed. A
devise rated for a flow rate of 50 litres per minute is recommended in order to maintain
maximum performance.
