Sealed Systems
23
The procedure for filling the sealed
system is as follows:
1. Check the air charge pressure in
the expansion vessel BEFORE filling
the system.
The expansion vessel charge pressure
should always be slightly greater than
the maximum static head of the
system, in bar, at the level of the vessel
(1 bar = 10.2 metres of water). See
Figure 6-2.
The charge pressure must not be
less than the actual static head at
the point of connection.
2. Check that the small cap (or screw)
on all automatic air vents (including
the one fitted at the left rear of the
boiler) is open at least one turn.
The cap (or screw) remains in this
position from now on.
3. Ensure that the flexible filling loop is
connected and that the double
check shut off valve connecting it to
the water supply is closed. A valve
is open when the operating lever is
in line with the valve, and closed
when it is at right angles to it.
3. Open the fill point valve.
4. Gradually open the double check
valve from the water supply until
water is heard to flow.
5. When the needle of the pressure
gauge is between 0.5 and 1.0 bar,
close the valve.
6. Vent each radiator in turn, starting
with the lowest one in the system,
to remove air.
7. Continue to fill the system until the
pressure gauge indicates between
0.5 and 1.0 bar. Close the fill point
valve. The system fill pressure (cold)
should be 0.2 - 0.3 bar greater than
the vessel charge pressure – giving
typical system fill pressures of
approx 0.5 bar for a bungalow
and 1.0 bar for a two storey house.
Refer to the Domestic Heating
Design Guide for further information
if required.
8. Repeat steps 5 and 6 as required
until system is full of water at the
correct pressure and vented.
9. Water may be released from the
system by manually operating the
safety valve until the system design
pressure is obtained.
10. Close the fill point and double
check valves either side of the filling
loop and disconnect the loop.
11. Check the system for water
soundness, rectifying where
necessary.
6.3 Venting the Pump
It is important that the pump is properly
vented to avoid an air lock and also
prevent it running dry and damaging the
bearings.
Unscrew and remove the plug from the
centre of the pump motor.
Using a suitable screwdriver, rotate the
pump spindle about one turn.
Replace the plug in the motor. Do not
overtighten.
6.4 Pressure Relief (Safety)
Valve Operation
Check the operation of the pressure
relief (safety) valve as follows:
1. Turning the head of the valve
anticlockwise until it clicks. The click
is the safety valve head lifting off its
seat allowing water to escape from
the system.
2. Check that the water is escaping
from the system.
3. Top-up the system pressure, as
necessary.
!
NOTE
The expansion vessel air pressure,
system pressure and operation of
the pressure relief valve must be
checked on an annual service. Refer
to Section 11.
!
NOTE
The air charge pressure may be
checked using a tyre pressure gauge
on the expansion vessel Schraeder
valve. The vessel may be re-
pressurised, when necessary, using a
suitable pump. When checking the
air pressure, the water in the heating
system must be cold and the system
pressure reduced to zero.
To Next Page
Loading...
