Technical data

1717
Installation requirements
Installation of Greenstar Highflow CDi combi boilers must
be in accordance with the relevant requirements of the
Gas Safety (Installation Use) Regulations at the time of
installation, current IEE Wiring Regulations, local Building
Regulations, Building Standards (Scotland) regulations
and bylaws of the local Water company and Health and
Safety Document No. 635 (Electricity at Work Regulations
1989). It should be in accordance with the relevant
recommendations of the following British Standards:
BS 6798; BS 5449; BS 5546:1; BS 5440:1; BS 5440:2;
BS 6891.
Gas Safety (Installation and Use) Regulations. All gas
appliances must be installed by a Gas Safe registered
person in accordance with the above regulations. Failure to
install appliances correctly could lead to prosecution.
The manufacturers notes must not be taken in any way as
overriding statutory regulations.
Sealed primary systems
Worcester Greenstar Highflow CDi combi boilers are
supplied complete with all the necessary components to
form a sealed primary system. Included are a pre-plumbed
expansion vessel (12 litres), a pressure relief valve (set at
3bar), an automatic air vent and a pressure gauge.
The expansion vessel fitted to the appliance will
accommodate differing system volumes, depending upon
its initial charge pressure, and system pre-pressurisation.
The table below shows the system volume that can be
accommodated under different conditions. If it is found
that the system volume exceeds that catered for by the
expansion vessel fitted within the appliance, then an
extra vessel should be added as close to the appliance as
possible in the heating return pipe. Refer to BS 5449:1
and BS 6798:1 for further information.
System filling and make-up
To comply with the Water Authority requirements, the
system should be filled via a temporary hose connection
to the mains cold water supply, with a double check valve
assembly and a test point fitted to the mains water side of
the temporary circuit. This is supplied within the boiler.
Valves and joints
It is very important that all valves and joints are able to
sustain a working pressure of up to 3bar (45psi). Particular
care should be exercised when fitting radiator valves and
only those of high quality to BS 2767:10 should be used.
All other valves and fittings should comply with BS 1010.
Loss of water pressure from a sealed system will require
continuous recharging with fresh water and consequential
introduction of air. Air is highly corrosive and will
considerably reduce life expectancy of radiators,
pumps etc.
Plastic pipework
The use of plastic pipework is acceptable. However, some
plastics are permeable to oxygen and must be avoided. Only
pipework with a polymeric barrier should be used. Please
note that the first 600mm of pipework connected to the
boiler must be copper.
Open vented primary systems
It is not permissible to install a Greenstar Highflow CDi
combi on an open vent system.
Total system volume – litres (gallons)
Initial system
pressure (bar)
Initial charge pressure (bar)
0.5 1.0 1.5
0.5 130 (29) – –
1.0 80 (17.5) 102 (22.5) –
1.5 43 (9.5) 58 (13) 71 (15.5)
2.0 20 (4.5) 27 (5.9) 33 (7.5)