23
2
1
fig. 32
GW 634/1
5.4 Filling the heating system
The boiler primary circuit and the
heating system should be filled using
a filling method as described in
Section 3.7.2.
Ensure that the boiler CH service
valves (3, fig. 31) are open.
Partially open the filling valve and
allow water to enter the system.
Starting with the lowest radiator, open
the radiator air release until water
(clear of bubbles) is emitted.
Repeat this at all radiators until the
complete system is full, all air locks
have been cleared and the boiler
pressure gauge reads 1.5 Bar.
Release any air from the pump by
slackening the centre screw (1, fig. 32).
The boiler is equipped with an
automatic air release valve. To allow
this to vent the boiler, the cap on top
(2, fig. 32) must be slackened by 1-2
turns. (This cap must be left slackened
during boiler operation to ensure any
residual air or system gases are
released).
Check the heating system and boiler
connections are sound.
5.5 Initial system flush ('cold')
The whole of the heating system must
be flushed out at least twice: once
cold, and once hot as instructed later
in Section 5.12.
Open all radiator or heating valves
and boiler CH service valves (3, fig.
31) and drain the heating system and
boiler completely from the lowest
points of the system via
1
/
2
in. BSP
drain taps (opened full bore to remove
any installation debris prior to lighting
the boiler).
Refill the heating system as described
in Section 5.4: Filling the heating
system.
Check the operation of the pressure
relief valve by rotating the knob on
the valve.
