15
Installation and Servicing
SECTION 1 - GENERAL
General
1.
The installation must comply with all relevant national and local
regulations.
2.
The installation should be designed to work with flow
temperatures of up to 84
o
C.
3.
All components of the system must be suitable for a working
pressure of 3 bar and temperature of 110
o
C. Extra care should
be taken in making all connections so that the risk of leakage
is minimised.
The following components are incorporated within the
appliance:
a.
Circulating pump.
b.
Safety valve, with a non-adjustable preset lift pressure of 3
bar.
c.
Pressure gauge, covering a range of 0 to 4 bar.
d.
An 8-litre expansion vessel, with an initial charge pressure
of 0.75 bar.
4.
‘Make-up’ Water.
Provision must be made for replacing water
loss from the system, either :
a.
From a manually filled ‘make-up’ vessel with a readily visible
water level. The vessel should be mounted at least 150mm
above the highest point of the system and be connected
through a non-return valve to the system, fitted at least
150mm below the ‘make-up’ vessel on the return side of
the radiators.
or
b.
Where access to a ‘make-up’ vessel would be difficult, by
pre-pressurisation of the system.
The maximum cold water capacity of the system should
not exceed 143 litres, if not pressurized. However, if
the system is to be pressurized, the efficiency of the
expansion vessel will be reduced and a larger vessel
(or smaller system volume) may be necessary. If the
capacity of the vessel is not considered sufficient for this,
or for any other reason, an additional vessel MUST be
installed on the return to the boiler.
Guidance on vessel sizing is given in table above.
5. Filling
The system may be filled by the following method:
Where the mains pressure is excessive a pressure reducing
valve must be used to facilitate filling.
a.
Thoroughly flush out the whole system with cold water.
b.
Fill and vent the system until the pressure gauge registers
1bar and examine for leaks.
c.
Check the operation of the safety valve by raising the
water pressure until the valve lifts. This should occur
within 0.3bar of the preset lift pressure.
d.
Release water from the system until the
minimum system design pressure is reached;
1.0 bar if the system is to be pre-pressurised.
Notes
a.
The method of filling, refilling, topping up or flushing sealed
primary hot water circuits from the mains via a temporary hose
connection is only allowed if acceptable to the local water
authority.
b.
Antifreeze fluid, corrosion and scale inhibitor fluids suitable for
use with boilers having aluminium heat exchangers may be used
in the central heating system.
1.16 SYSTEM REQUIREMENTS - Central Heating
Water Flow Rate and Pressure Loss
Max CH Output
kW
24.2
Water flow rate
l/min
17.3
(gal/min) (3.8)
Temperature Differential
o
C 20
Head available for
m.w.g.
3.4
system
(ft.w.g.) (11.1)
Safety valve setting
bar
3.0
Vessel charge pressure
bar
0.5 to 0.75
System pre-charge pressure
bar
None
1.0
System volume
Expansion vessel
(litres)
volume (litres)
25
1.6 1.8
50
3.1 3.7
75
4.7 5.5
100
6.3 7.4
125
7.8 9.2
150
9.4 11.0
175
10.9 12.9
190
11.9 14.0
200
12.5 14.7
250
15.6 18.4
300
18.8 22.1
For other system volumes
multiply by the factor across
0.063 0.074
continued . . . . .
CH Return
6053
Hose unions
Mains
water supply
Temporary hose
(disconnect after filling)
Additional
stop valve
Double check valve
assembly
(
note direction of flow
)
