APR 2018
4
Hot Water Energy Storage
Unvented Cylinders
GB & NI
Installation & Maintenance Instructions for an unvented
hot water cylinder with external thermal expansion
SITING THE UNIT
The unvented cylinder can supply outlets above it or at
some distance from it. Site the unit to minimise “dead leg”
distances, especially to the point of most frequent use.
Outlets above the unvented cylinder will reduce the outlet
pressure available by 0.1 bar for every 1m of height difference.
The unit should be protected from frost. Particular care is
needed if siting in a garage, outbuilding or loft space. All
exposed pipework should be insulated. The unvented cylinder
must be installed in the correct orientation i.e. vertically
(unless you’re using a horizontal model), on a flat base
capable of supporting the weight of the cylinder when full.
See technical specification insert sheet for weights. The
minimum recommended cupboard size for vertical models is
750mm square.
Access
Consideration should be given to the position of discharge
pipes (tundish) drain valves. Avoid positioning these too close
to electrical devices and components. Also allow sufficient
space so that the cylinder can be inspected, maintained and
serviced in the future.
The immersion heaters are 400mm long and care should be
taken to ensure that they can be withdrawn, enabling the
immersion heater to be replaced at the end of its working life
and providing inspection access to the interior of the cylinder
in servicing if required.
The discharge pipework from the safety valves should fall
continuously and terminate safely.
Cradles
Horizontal cylinders are provided with two support cradles.
One of the cradles is fitted with a locating pin, this must be
fitted into the corresponding location hole at the end of the
cylinder with the T&P valve - this is to ensure that the T&P
valve is the highest point on the cylinder. Position the other
cradle a quarter of the way along from the opposite end.
STORAGE PRIOR TO INSTALLATION
The unvented cylinder should be stored in its original
packaging in an upright position in an area free from
excessive moisture.
HANDLING PRODUCT
The unvented cylinder should be carried upright where
possible. Assessments of risks for carrying the cylinder should
be conducted. Use more than one person for carrying where
appropriate. Never carry the cylinder using the pre-plumbed
pipework or components. Always follow latest guidelines for
lifting techniques, to avoid injury, or damage to the product.
WATER SUPPLY
The unvented cylinder operates at 3 bar (controlled by the
inlet control set) and is capable of delivering over 50 litres per
minute. The high quality inlet control set has been designed
to make the most of the flow rates available, however the
performance of any unvented system is only as good as the
mains water supply. The maximum possible water demand
should be assessed, taking into consideration that both
hot and cold services are supplied simultaneously from the
mains.
The water supply should be checked to ensure it can
meet these requirements. If necessary, consult the local
water company regarding the likely pressure and flow rate
availability.
If measuring the water pressure, note that a high static
(no flow) mains pressure is no guarantee of good flow
availability. In a domestic installation 1.5 bar and 25 l/min.
should be regarded as the minimum. The maximum mains
pressure that the inlet control set can accept is 12 bar.
Consideration should be given to upgrading existing
1/2” (15mm) cold mains pipework to a larger size if the
recommended minimum pressure/flow rate is not being
achieved.
ELECTRICITY SUPPLY
The unvented cylinder requires 240 Volt electrical supply
for the immersion elements. The electrical supply to each
immersion heater must be fused at 13A via a double pole
isolating switch that meets the current BS Standards. The
cable must be at least 2.5mm
2
heat resistant (85°C HOFR)
sheathed flex complying to the current BS Standards
PREPARING TO INSTALL THE CYLINDER
