Water Systems And Pipe Work - Worcester GREENSTAR 24 Installation, Commissioning And Servicing Instructions

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
Fig. 3
[1] Mini expansion vessel - part no. 7 716 192 105
[2] Mains water inlet pipe
[3] Non return valve
[4] Boiler
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.
3.3

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.
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).
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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-syphon 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.
SEALED PRIMARY SYSTEM:
NOTICE: ARTIFICIALLY SOFTENED WATER MUST NOT
BE USED TO FILL THE CENTRAL HEATING SYSTEM
• The CH sealed system must be filled using a WRAS approved filling
loop or comply with figure 4 for system fill.
• Where the system volume is more than 100 litres or exceeds 2.65
bar at maximum heating temperature, an extra expansion vessel (2)
must be fitted as close as possible to the appliance in the central
heating return.
• Pressurise the extra expansion vessel (2) to the same figure as the
expansion vessel built into the appliance.
• Do not use galvanised pipes or radiators.
SYSTEM FILL
Heating
return
Hose union
SV
Temporary hose
CV = Check Valve
SV = Stop Valve
Fig. 4 System fill
TYPICAL SEALED SYSTEM
1
2
3
4
Fig. 5 Sealed system
Pre-Installation
Mains
supply
CV
CV
SV
Test point
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5 5
5 5
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