6.1
A separate vent for combustion air is not required. Refer to
BS5440:2.
The system must comply with requirements of BS6798 and
BS5449 and, in Eire, the current edition of IS813. It must not be
operated without being full of water and correctly pressurised.
The pressure relief valve will operate at 3 bar. The discharge pipe,
of 15mm diameter, must be directed such that the discharge of
water or steam is visible, will not discharge onto the occupants
of the premises or cause any damage to the premises, in
particular any electrical components or wiring.
The expansion vessel, to BS4814, has a capacity of 6 litres
charged to 0.5 bar, which is suitable for a static head of 5 metres.
A schraeder type valve allows the pressure to be increased if the
static head is greater than 5 metres.
If the expansion vessel fails then it must be replaced with the
designated spare part.
Refer to BS 7074:1, BS5449 and Table 9 for a guide to the
available system capacity. The maximum system design pressure
is 1.5 bar. If the pressure is above 2.65 bar when the appliance is
at maximum temperature then an additional expansion vessel
must be fitted as near to the appliance as possible in the return
pipe. The pressure gauge shows the system pressure.
Fill and pressurise the system through a WRAS approved filling
loop.
The system and the appliance must be fully vented
. Repeated
venting loses water from the system, which must be replaced.
The make-up connection must be close to the appliance in the
heating return pipe through an approved non-return valve.
Plastic pipes must not be directly connected to the boiler. A
copper to plastic transition piece should be positioned a
minimum of 600mm from the boiler. A plastic pipe with a
polymeric barrier must be used.
The connection to the mains water supply must have the
approval of the local Water Company.
An integral non-adjustable by-pass is fitted .
The pump is set at maximum and should not be adjusted.
All connections in the system must withstand a working pressure of up
to 3 bar.
The radiator valves must conform to BS 2767:10 and other
valves to BS1010.
This appliance is NOT suitable for connection to an open vent
system.
7. Sealed System
6. Air Supply
9
Fig. 7. Sealed primary water system.
Lockshield
valve
Radiator
valve
Heating
return
Hot water out
Water main
British Standard stop valve.
Fixed spindle type
NOTE:
A drain cock should be installed at the
lowest point of the heating circuit and below the
level of the appliance.
Mains cold
water
Heating
flow
APPLIANCE
Refer to 'Water
Flow Diagram'
Fig.2.
Cold water inlet
8. Open Vent System
Fig 8a - System make up
1.Central Heating Return
2.Auto Air vent
3.Non-return Valve
4.Make-up Vessel
5.Stop Cock
4
1
2
3
5
300mm Above
the highest point
of the system
Fig 8b - Filling loop
Heating
return
Stop
cock
Hose union
Temporary hose
Non return
valve
Non return
valve
Test cock
Mains water
supply
