Table of Contents
Advertisement
7.2
fiLLinG thE hEatinG SYStEM
Filling of the system must be carried out in a manner approved by
the local Water Undertaking.
! WaRninG !
Only ever fill or add water to the system when it is cold and
the boiler is off. Do not overfill.
The procedure for filling the sealed system is as follows:
1.
Check the air charge pressure in the expansion vessel
BEFORE filling the system.
! nOtE !
the air charge pressure can only be correctly checked
when the system water pressure is zero.
The expansion vessel air 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).
For example: If the height to the top of the highest radiator
from the centre of the expansion vessel is 5metres, then the
static head at the vessel would be 0.5 bar. Refer to Figure
7-2.
The air charge pressure must not be less than the actual
static head at the point of connection.
! 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 charge pressure,
the water in the heating system must be cold and the
system pressure reduced to zero.
2.
Check that the small black plug on the side of both automatic
air vents is unscrewed one turn. Also check that the cap on
the manual air vent is unscrewed one turn. Refer to Section
4.10.
3.
Ensure that the flexible filling loop is connected between the
double check valve (on the cold water pipe) and the filling
point on the drain cock connection in the lower right corner of
the boiler.
Also ensure that the shut off valves on both the double check
valve and the fill point are closed.
Note that these valves are open when the operating lever is
in line with the valve, and closed when it is at right angles to
it.
4.
Open the shut off valve on the fill point valve.
5.
Gradually open the shut off valve on the double check valve
until water is heard to flow into the system from the cold
water supply.
6.
When the needle of the pressure gauge is between 0.5 and
1.0 bar, close the shut off valve on the double check valve.
7.
Vent each radiator in turn, starting with the lowest one in the
system, to remove air.
8.
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 air charge pressure.
Refer to the Domestic Heating Design Guide for further
information if required.
9.
Repeat steps 4 and 5 as required until system is full of water
at the correct pressure and vented.
10. Water may be released from the system by manually
operating the safety valve until the system design pressure is
obtained.
11. Close the shut off valves on the fill point and double check
valves and disconnect the filling loop.
12. Check the system for water soundness, rectifying where
necessary.
page 22
7.3
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.
Section 7: Sealed Systems
Hide quick links:
Advertisement
Table of Contents
