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INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER BOSCH
8-716-106-252a (03.05)
WATER SYSTEMS & PIPEWORK
9
PRIMARY SYSTEM PLASTIC PIPEWORK:
Any plastic pipework must have a polymeric
barrier with 1000mm (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.
An automatic bypass valve must be connected
between the heating flow and return where TRV's
are used on all radiators.
Drain cocks are required at all the lowest points
on the system.
Air vents are required at all high points on the
system.
OPEN VENT PRIMARY SYSTEM:
In order to comply with BS 5549 the feed and
expansion pipe and the open vent pipe, (or the
combined feed and vent pipe), must be
connected to the 1 BSP outlet/s on the right
hand side of the primary heat exchanger.
The feed and expansion cistern (E) must be
positioned to provide a static head (S) of at least
1 metre above the highest point in the heating
system to the water level in the feed and
expansion cistern (E).
No valve shall be fitted in the open vent pipe (H)
or the feed and expansion pipe (F).
The heating vent pipe (H) must be at least
22mmØ.
SEALED PRIMARY SYSTEM:
Where the system volume is more than 180 litres
at 0.5 bar 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 OPEN VENT SYSTEM
A - Appliance expansion vessel
B - Extra expansion vessel
C - Automatic bypass valve
D - Drain cock
E - Feed & expansion cistern
F - Feed & expansion 15mmØ min
G - Appliance
H - Open vent 22mmØ min
L - Lockshield valve
P - Pressure relief discharge
R - Radiators
S - Static head
T - T.R.V.
U - To filling system
D
R
R
R
R
C
T
L
T
L
T
L
T
L
E
S
1000mm min.
F
G
D
TYPICAL SEALED SYSTEM
D
R
R
R
R
B
P
D
C
T
L
T
L
T
L
T
L
A
U
H
G
