12
e)
If ther
mostatic radiator valves are fitted, a radiator must be
fitted with two lock shield valves, to enable correct operation of
the pump over-run facility.
f)
The following paragraphs outline the specifications of the
items fitted to the appliances.
PUMP
– The available pump head shown in Figur
e 6 is that in
excess of the appliance hydraulic resistance, i.e. that available
for the system.
BY
-PASS
– The boiler is not fitted with an inter
nal by-pass. An
automatic by-pass is required if the boiler is installed to a ‘Y’ or
‘S’ plan system (See Figures 9 and 11) to ensure adequate pump
over-run function.
EXP
ANSION VESSEL –
The integral expansion vessel is pr
e-
charged to a pressure of between 0.5 and 1.0 bar. This should
be checked before the water system is filled. Details below show
the water system volume that is acceptable for this vessel. If the
system water volume is larger then an additional vessel must be
fitted to the system. BS 5449 and BS 6798 give further details
regarding expansion vessel sizing and sealed systems.
Expansion V
essel Requirements
V
essel charge and
bar
0.5
0.75
1.0
1.5
initial system pressure
Total water content of system
using 8 L (1.54 gal) capacity
L
96
84
73
50
expansion vessel supplied
with appliance.
For systems having a larger
capacity multiply the total system
capacity in litres (gallons) by
0.0833 0.093 0.109 0.156
these factors to obtain the total
minimum expansion vessel
capacity required in litres.
PRESSURE GAUGE –
A pr
essure gauge is situated on the
appliance control panel.
PRESSURE RELIEF V
ALVE –
A pr
essure relief valve set to 3 bar
(43.5 psi) is supplied with the appliance, however it will start to
open at approximately 2.7 bar. It should not be used to flush the
system.
FILLING LOOP -
This boiler is not fitted with a filling loop. Any
filling loop being fitted should comply with the current water
supply (water fittings) regulations. A filling loop should be fitted
at some point to allow the CH system to be filled. Two types are
shown in Figure 7.
W
ATER TREATMENT, CLEANSING AND FLUSHING THE
HEATING SYSTEM
NOTE:
British Standard BS7593: 1992 stresses the importance of
cleansing and flushing of the system to ensure it continues to run
efficiently with the minimum of maintenance necessary. Halstead
Boilers fully support this professional approach and recommend
that the system is cleansed with an effective chemical cleanser
and protected long term with a suitable inhibitor. Such products
are available from Fernox and Sentinal.
7
AL
TERNATIVE METHODS OF FILLING A SEALED SYSTEM
MAINS W
ATER
SUPPLY
FLEXIBLE HOSE UNION
TEMPORARY CONNECTION
To be removed immediately after filling
STOP
VALVE
DOUBLE
CHECK
VALVE
ASSEMBLY
STOP
VALVE
HEATING SYSTEM
RETURN
MAINS
WATER SUPPLY
CISTERN &
OVERFLOW
PRESSURE PUMP &
REDUCING VALVE
IF REQUIRED
STOP
VALVE
HEATING
SYSTEM
RETURN
RECOMMENDED AND APPROVED METHOD FOR
FILLING CLOSED CIRCUIT IN A HOUSE.
(R24-2a WATER REGULATIONS GUIDE)
A
VAILABLE PUMP HEADS
6
