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INCOMING COLD SUPPLY
M
DC
DC
DC
TO
EXTERNAL
TAP
SINK
WATER SOFTENER (IF NECESSARY)
WM or DWM
WHB W.C.
DC
DC
SH
DHW
WHB
WC BATH
SCV SCV
P&T
ERV/NRV
PRV
DCV
Note:
Cold supplies to single taps must be
taken from the mains cold water
system.
Cold supplies to mixer taps must be
taken from the balanced cold water
connection on the combination
valve.
General Design Considerations
The cupboard footprint needs to be at least 650mm square for standard units up to
300 litres, 730mm for 400 litre and 575mm for slimline units. The base chosen for the
cylinder should be level and capable of supporting the weight of the unit when full of
water as shown in General Data. The discharge pipework for the safety valves must have
a minimum fall of 1 : 200 from the unit to a safe discharge point. All exposed pipework
and ttings on the cylinder should be insulated, and the unit should NOT be xed in a
location where the contents could freeze.
In new systems, pipes should be insulated to comply with building regs, the maximum
permissible heat loss is indicated in the table opposite, and labelled accordingly as follows:
i. Primary circulation pipes for domestic hot water circuits should be insulated
through their length, subject only to practical constraints imposed by the need
to penetrate joists and other structural elements.
ii. All pipes connected to hot water storage vessels, including the vent pipe, should
be insulated for at least 1 metre from their points of connection to the cylinder (or
they should be insulated up to the point where they become concealed).
In replacement systems, whenever a boiler or hot water storage vessel is replaced in
an existing system, any pipes that are exposed as part of the work or are otherwise
accessible should be insulated as recommended for new systems, or to some lesser
standard where practical constraints dictate.
The pipe connecting the boiler ow to the appliance must not be less than 22mm
copper or equivalent.
Standard and Slimline Model Selection Guide
Max hot water demand
Max number
of bed spaces
(Bedrooms)
Indirect
litres
Direct
litres
1 shower room Bedsit (0) 90 120
1 bathroom 2 (2) 120 150
1 bathroom 4 (3) 120 180
1 bathroom + separate shower room 6 (4) 150 210
1 bathroom + 2 separate shower rooms
or 2 bathrooms 7 (5) 180 210
2 bathrooms + separate shower room 7 (5) 210 250
2 bathrooms + 2 separate shower rooms 7 (5) 250 300
3 bathrooms + 2 separate showers rooms 9 (6) 300 -
General Restrictions
a. The highest hot or cold water draw o point should not exceed 10 metres above
the Pressure Reducing Valve.
b. An ascending spray type bidet or any other appliance with a Class 1 back-syphonage
risk requiring a type A air gap should not be used.
c. StainlessLite Plus should not be used where steam is the primary heating medium,
or in a situation where maintenance is likely to be neglected.
d. Unvented cylinders are not suitable for use with solid fuel boilers.
e. If the supply to the mixer ttings (other than a dual outlet type) is not taken from
the balanced supply the system will become over pressurized and cause the
pressure relief valve to discharge. Over time this could also cause the premature
failure of the appliance itself which will not be covered by the warranty.
f. In larger properties with a number of bathrooms/en-suites and long pipe runs
we would recommend that the balance cold supply is provided with its own
pressure reducing valve and is not taken from the balanced cold connection on
the combination valve. In this case it will also be necessary to t a small expansion
vessel on the balanced cold water system to accommodate the pressure rise caused
by the increase in temperature of the balanced cold water.
g. Check the performance requirements of the terminal ttings with regard to ow/
pressure are suitable.
h. In relation to potable water systems, expansion vessels shall be installed in a vertical
orientation and located so that the length of the connecting pipe work is kept to
a minimum.
Shower Fittings
Aerated taps are recommended to prevent splashing. Any type of shower mixing valve
can be used as long as both the hot and cold supplies are mains fed. However, all mains
pressure systems are subject to dynamic changes particularly when other hot and cold
taps/showers are opened and closed, which will cause changes in the water temperature
at mixed water outlets such as showers. For this reason and because these are now no
more expensive than a manual shower we strongly recommend the use of thermostatic
showers with this appliance. These must be used in 3 storey properties where the
impact on pressure/temperature of opening another tap in the system is greater than
normal. The shower head provided must also be suitable for mains pressure supplies.
Pipe Layout
In all mains pressure installations it is important
to remember that the incoming cold supply
must be shared between all terminal ttings. It
is important that a 22mm supply is brought to
the appliance and a 22mm take-o is continued
at least to the bath. If there are two baths, 28mm
pipework should be considered. One metre of
smaller diameter pipework, or ow restrictors,
should be provided on the nal connection to
all outlets so as to balance the water available.
In any event the distribution pipework should
generally be in accordance with BS EN806-1 to 5.
Plastic Pipework
This appliance is suitable for use with plastic
pipework as long as the material is recommended
for the purpose by the manufacturer and is installed
fully in accordance with their recommendations.
Secondary Hot Water Circulation
All models 210 litres and above are tted with
a secondary return tapping as standard (see
tables 1 and 2 for details). If tted, an extra
expansion vessel may be necessary. A non-
return valve MUST be FITTED near the return
connection. No valve or terminal tting should
be installed between the non return valve and
the cylinder. (See schematic arrangement on
page 15.) All pipes kept hot by the secondary
circulation should be insulated.
Solar Model Selection Guide
Max hot water demand Bedrooms Indirect
litres
Direct
litres
1 shower room Bedsit - 180
1 bathroom 1-3 180 -
1 bathroom 1-3 210
1 bathroom + 1 shower room 1-3 210 -
1 bathroom + 1 shower room 1-3 - 250
1 bathroom + 2 shower rooms 2-4 250 -
1 bathroom + 2 shower rooms 2-4 - 300
2 bathrooms + 1 shower room 3-4 300 -
2 bathrooms + 2 shower rooms 4-5 400 -
INSTALLATION INSTALLATION
INSTALLATION INSTALLATION
Further guidance on converting heat loss limits
to insulation thickness for specific thermal
conductivities is available in TIMSA “HVAC
guidance for achieving compliance with Part L
of the Building Regulations”.
Mains Water Supply
Existing properties with a 15mm supply will be
satisfactory provided the local mains pressure is
good, but should be conned to single bathroom
properties. For newproperties wheresimultaneous
demand is required to more than one bathroom
or a bathroom and one or more en-suites, the
communication and service pipe into the dwelling
should be a minimum of 22mm (usually in the
form of a 25mm MDPE supply). The optimum
performance is achieved if the inlet pressure is
3 bar dynamic. However, the StainlessLite Plus
will function with lower inlet pressures, but
this will reduce the performance. For optimum
performance, 30L per minute incoming mains ow
should be present, however the StainlessLite Plus
will work at lower ow rates, although performance
will be affected. Normally StainlessLite Plus
provides well in excess of 40 litres/min in most
conditions. Flow rates for ALL mains pressure
systems are subject to district pressures and system
dynamic loss. Particularly on larger properties with
more than one bathroom, the pipe sizes should be
calculated in accordance with BS EN 806-3:2006
and BS 8558:2011.
Model Selection
The suggested Direct model sizes, shown
opposite, are based on a typical days hot water
use assuming an Economy 7 tari is provided.
A reduction of one model size can normally
be made with an Economy 10 tariff. When
using the Direct models for high specication
developments an increase of one model size
should be considered.
The suggestedmodel sizesare basedon typicalhot
water usage. For high specication dwellings an
increase of one model size should be considered.
Insulation of pipework
Pipe outside
diameter
Maximum
heat loss
15mm 7.89W/m
22mm 9.12W/m
28mm 10.07W/m
35mm 11.08W/m
