PRE-INSTALLATION
6 720 812 175 (2014/07)
10
3.3
WATER SYSTEMS & PIPE WORK
PLASTIC PIPE WORK:
• Any plastic pipe work must have a polymeric barrier with 600 mm
(minimum) length of copper or steel pipe 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 approx. 50°C.
The pipe work from the boiler to the blending valve must be in copper
or steel (protected from corrosion).
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
• On new installations, or extensions to existing systems where a
radiator previously did not exist, each radiator should be fitted with a
TRV, except the one fitted in the same room/area as the thermostat.
• On boiler only replacement jobs, it is recommended, (but not
mandatory,) to fit a TRV on each radiator.
• An automatic bypass may be required, (downstream of the pump), in
order to maintain the minimum flow-rate through the appliance.
• A drain cock is required at the lowest point on the system.
• An air vent is required at the highest point on the system.
A - Diverter Valve
B - Automatic Bypass
C - Radiator Valve (Flow)
D - Lockshield Valve (Return)
E - Extra expansion Vessel
• The sealed system must be filled using a WRAS approved filling loop
or comply with the diagram opposite 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 (E) must
be fitted as close as possible to the appliance in the central heating
return.
• Pressurize the extra expansion vessel (E) to the same figure as the
expansion vessel built into the appliance
• Do not use galvanised pipes or radiators.
• A drain cock is required at the lowest point on the system.
Fig. 6
A
C
D
B
E
A
C
D
E
B
Cylinder
return
Cylinder flow
Heating
flow
E
B
C
D
Heating
return
Heating return
Hose
Non return
value
Non return
value
Test cock
Mains
supply
Stop cock
Stop
cock
Temporary hose
return
Heating return Auto
air vent
Non
return value
Stop
value
Make up
vessel
1000mm (39in)
above the
highest point of
the system
S plan layout
Y plan layout with external diverter valve
System layout with optional internal diverter valve
fitted (not supplied with the boiler.
System fill
System make up
6720647472-04.1Wo