Technical data

See Fig. 7.
7b.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.
7b.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.
7b.3 The feed and expansion cistern should be arranged so that
a minimum static head of 1.0m above the top of the appliance or
above the highest point in the heating circuit, whichever is the
highest, is achieved. See Fig. 7.
7b.4 The feed and vent pipe must rise continuously from the
appliance to the feed and expansion cistern.
7b.5 A pressure relief valve is not required on an open vented
system. With the pressure relief 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.
7b.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.
7b.7 The pump is set to maximum and must not be reset.
7b. Open Vent Primary System
10
Hot Water
Out
S.H. S.H.
Mains
Cold
Water
Lockshield Valve Radiator Valve
Heating Flow
Heating
Return
22mm dia. Vent Pipe
Circulating Pump
Combined feed and vent
pipe (22mm).
Must rise continuously.
British Standard Stop
Valve.
Fixed spindle type
Water Main
NOTE:
A Drain Cock should be
installed at the lowest point of the
heating circuit and beneath the
appliance.
STATIC HEAD (S.H.)
Minimum Static Head 1.0m. 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.
Appliance
(Refer to
Fig. 1
for appliance
Water Flow
diagram)
Part view
showing
Vent Pipe
connection
Fig. 7. Open vent water system.
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.