Open Vent System - Worcester Highflow 400 RSF Installation And Servicing Instructions

8. Open Vent Primary System
See Fig. 8.
8.1 The appliance is supplied suitable for connection to a sealed
system. If it is to be used with an open vent system then the
instructions given below must be followed.
8.2 A 22 mm preformed combined feed and vent pipe
available as an optional extra must be connected to the
appliance. See Section 11.3 and Fig. 18.
Note: Refer to Section 2 – Table 4, for the sizes of the flow and
return pipework.
8.3 The feed and expansion cistern should be arranged so that a
minimum static head of 1.0m (39 in) above the top of the
appliance or above the highest point in the heating circuit,
whichever is the highest, is achieved. See Fig. 8.
Fig. 8. Open vent water system.
STATIC HEAD (S.H.)
Minimum Static Head 1.0m (3ft). Measured
from the top surface of the appliance or the
highest point in the heating system to the
water level in the feed and expansion tank.
Lockshield Valve
NOTE:
A Drain Cock should be
installed at the lowest point of the
heating circuit and beneath the
appliance.
Radiator Valve
Heating Flow
Disconnect the flexible hose from behind the
circulating pump. The expansion vessel and
flexible hose are not required in the open vent
system and may be discarded. Fit the 22mm
vent pipe supplied as on optional extra.
12
8.4 The feed and vent pipe must rise continuously from the
appliance to the feed and expansion cistern.
8.5 A safety valve is not required on an open vented system.
With the safety valve left in position a pipe must be fitted which
terminates such that any discharge does not cause a hazard to
the occupants or damage to electrical components.
8.6 Air within the appliance will be expelled via the feed and
vent connection or dissipated into the rest of the system which
must be fitted with manual air vents at any high point.
8.7 The pump is set to maximum and must not be reset.
Hot Water
Out
Mains
Cold
Water
Appliance
(Refer to
Fig. 1
for appliance
Water Flow
diagram)
Part view
showing
Vent Pipe
connection
Heating
Return
22mm dia. Vent Pipe
Circulating Pump
Combined feed and vent
pipe (22mm).
Must rise continuously.
Spherical Plug Ball Valve for
appliance servicing
British Standard Stop
Valve.
Fixed spindle type
Water Main