APR 2018
7
Hot Water Energy Storage
Unvented Cylinders
GB & NI
Installation & Maintenance Instructions for an unvented
hot water cylinder with external thermal expansion
BALANCED CONNECTIONS
Where there are showers, bidets or monobloc mixing taps in
the installation, these should be installed to comply with the
Water Supply (Water Fittings) Regulations 1999.
If these devices have un-balanced supplies there should be
single check valves installed at both inlets, to stop over-
pressurisation of either supply. A balanced cold supply is
necessary.
On some cylinder models the inlet control set, features a
22mm balanced cold connection, refer to the spare parts
list on the insert sheet for details. This connection must be
capped off if not used.
HOT WATER PIPEWORK
Run the first part of the hot water distribution pipework in
22mm. This can be reduced near to the outlet to 15mm or 10mm
if appropriate, for example to suit the type of tap. You should
aim to keep the run length of any hot water pipework from the
cylinder to outlet to a practical minimum so the time taken for
the hot water to reach the outlet is as quick as possible.
Then connect the hot water pipework to the hot water draw-
off on the cylinder (Position B in the diagrams on pages 11-17).
CONNECTIONS FOR INDIRECT UNITS
For Solar input models refer to the shaded box before making
any connections.
Connect the primary connections using the compression
connections provided. The primary circuit must be positively
pumped. Gravity circulation is not suitable. For heat pump
coils use the top primary connection as the primary flow,
reheat times will be effected if connecting the flow to the
opposite end of the coil.
Either primary connection may be used as the primary flow,
reheat times are not affected. The primary circuit can be
open vented or sealed, up to a maximum pressure of 3.5 bar.
If you seal the primary circuit an additional expansion vessel
and safety valve is required.
Connect the two port valve into the primary flow pipework.
The direction of the flow arrow should be towards the
primary flow connection.
Where connecting to a boiler, the boiler can be Gas, Electric
or Oil, but must be under effective thermostatic control.
Uncontrolled heat sources such as some AGAs, back boilers,
solid fuel stoves, etc. are not suitable. Please contact our
Technical department for guidance.
On pre-plumbed models (page 12), connect to the boiler flow
and return Positions F & G, for single zone heating systems
connect the radiator circuit to Positions H & J and with twin
zone heating systems connect the second zone to Positions I &
J. Note, pre-plumbed models are supplied with an additional
expansion vessel and safety valve for the heating circuit. Consult
the boiler manufacturer’s instructions to confirm sizing is
suitable for the heating system and guidance on positioning.
INSTALLATION INSTRUCTIONS (CONTINUED)
SOLAR INDIRECT UNVENTED
(TWIN COIL)
Upper coil
The upper coil is connected to the fossil fuel boiler or
heat pump as per the instructions for the unvented
indirect single coil model, with the dual stat control and
high limit thermostat inserted into pocket G2 (boiler)
or Pocket G1 (heat pump see page 17). The wiring
requirements are shown on page 18.
Lower coil: solar installation
The flow and return from the solar heat source are to
be connected to the bottom coil. Either primary coil
connection may be utilised as the flow or return. The
solar primary circuit must have its own dedicated
circulating pump, thermal and safety controls, which
must be installed as per the solar manufacturer’s
instructions. The solar control system used must be
of the solar differential control type and should be
connected to the solar sensor.
The solar sensor, supplied as part of the solar controls
should be inserted into Pocket G1 (boiler) or Pocket B
(heat pump) and is held in-situ with the black sensor
pocket retaining bung provided.
It is necessary to connect the solar pump via the
overtemperature high limit cut-out (provided) to
ensure the heat input to the solar coil is interrupted
if the cylinder overheats. Some method to prevent
thermosyphoning must also be employed. Non-return
check valves in the primary flow and return pipework
would be acceptable. If solar controls do not offer
appropriate isolation, a two port zone valve (not
supplied) can be used with the pump and high limit stat
as shown on page 18.
Note:
If it is intended to fit a cylinder with a solar coil
to be used at a later date, the two coils should be
connected in series to make use of the solar coil, using
the dual stat in Pocket G2 (boiler) or Pocket G1 (heat
pump), as shown in the diagram on page 16 & 17.
The Domestic Heating Compliance Guide document L1A
and L1B provides excellent advice in sizing both cylinder
dedicated solar areas and heat exchangers to the
surface area of the solar collectors. Using this guide we
are able to offer sizing advice for specification.
Note:
Consult all details of the compliance guide
documentation prior to specifying product or
commencing design.