Water Supply; Water Systems And Pipe Work - Worcester Greenstar 25Si Compact Installation, Commissioning And Servicing Instructions

4.2.3 Water supply

Use in hard water areas:
Normally there is no need for water treatment to prevent scale formation
as the maximum temperature of the DHW heat exchanger is limited by
the electronic control.
In areas where temporary water hardness exceeds 200 ppm,
consideration may need to be given to the fitting of a scale prevention
device. In such circumstances, the advice of the local water authority
should be sought.
Water mains pressure:
• Minimum mains water pressure for maximum performance: refer to
the Technical data in section 3.3.
• Maximum mains fed water pressure 10 bar.
If necessary fit a pressure reducing valve.
NOTICE: Non return, back flow prevention devices
(including those associated with water meters) fitted to
the mains water supply can cause a pressure build up
which could damage the boiler and other household
appliances.
• Where the mains water supply has a non-return,
back flow prevention valve fitted, a mini expansion vessel (1) should
be connected to the mains water inlet pipe (2) between the non-
return valve (3) and the boiler (4) as shown below.
1
2 3
1 Mini expansion vessel - part no. 7 716 192 105
2 Mains water inlet pipe
3 Non return valve
4 Boiler
4.3

Water systems and pipe work

PLASTIC PIPE WORK:
• Any plastic pipe work must have a polymeric barrier with 600mm
(minimum) length of copper pipe before being connected to the
boiler.
• Plastic pipe work used for underfloor heating must be correctly
controlled with a thermostatic blending valve limiting the temperature
of the circuits to approximately 50°C.
PRIMARY SYSTEMS CONNECTIONS/VALVES:
• All system connections, taps and mixing valves must be capable of
sustaining a pressure up to 3 bar.
• Radiator valves should conform to BS2767:10.
• All other valves should conform to BS1010.
• Thermostatic radiator valves (TRV's) must be fitted to all rooms
except bathrooms and the room in which the room thermostat is
fitted.
• A drain cock is required at the lowest point(s) in the system.
• An air vent is required at the high point(s) in the system.
Greenstar Si Compact ErP - 6 720 813 278 (2015/07)
4
6720643895-04.1Wo
The boiler is equipped with an internal by-pass.
The internal bypass is not intended to be a substitute for
an external system bypass.
An external automatic bypass should be used if the
system flow can be significantly adjusted or stopped by
zone valves and thermostatic radiator valves (TRV).
SHOWERS/BIDETS:
• If a shower head can be immersed in water or comes closer than
25mm from the top edge of a bath or shower tray spill over level then
an anti-siphon device must be fitted to the shower hose.
• Bidets with direct hot and cold mains water can be used (with the
approval of the local water authority) and must be the over rim
flushing type with shrouded outlets to prevent the fitting of hand held
sprays.
PRE-INSTALLATION
13