PR
E-
IN
S
TA
LL
AT
IO
N
INSTALLATION & SERVICING INSTRUCTIONS
6-720-611-730b (12.05)
9
WATER SYSTEMS & PIPEWORK
PRIMARY SYSTEM PLASTIC PIPEWORK:
Any plastic pipework must have a polymeric
barrier with 600mm (minimum) length of copper
or steel pipe connected to the boiler.
Do not use plastic pipework on sealed systems.
Plastic pipework used for underfloor heating
must be correctly controlled with a thermostatic
blending valve limiting the temperature of the
circuits to approx. 50°C. The pipework from the
boiler to the blending valve must be in copper
or steel (protected from corrosion).
PRIMARY SYSTEM/CONNECTIONS/VALVES:
Do not use galvanised pipes or radiators.
All system connections, taps and mixing valves
must be capable of sustaining a pressure of 3
bar.
Radiator valves should conform to BS2767:10.
All other valves should conform to BS1010.
On new installations TRVs must be used on all
radiators except the radiator where the room
thermostat is sited, this must be fitted with
lockshield valves and left open. All installations
should have TRV's fitted to radiators within the
sleeping accommodation.
Drain cocks are required at all the lowest points
on the system.
Air vents are required at all high points on the
system.
SEALED PRIMARY SYSTEM:
Where the system volume is more than 100 litres
or exceeds 2.65bar at maximum heating
temperature an extra expansion vessel (B) must
be fitted as close as possible to the appliance
in the central heating return.
Pressurise the extra expansion vessel (B) to the
same figure as the expansion vessel built into
the appliance.
WATER SYSTEMS & PIPEWORK
TYPICAL SEALED SYSTEM:
A - Appliance expansion vessel
B - Extra expansion vessel
C - Automatic bypass valve
D - Drain cock
L - Lockshield valve
P - Pressure relief discharge
R - Radiators
T - TRV
D
R
R
R
R
B
P
D
C
T
L
T
L
T
L
T
L
A