7. Sealed System
See Figs. 4.
7.1The system must comply with the requirements of BS 6798 and BS 5449.
7.2The appliance must not be operated without the system being full of water, properly vented and pressurised.
7.3The pressure relief valve operates at 3 bar (45lb/in2). The discharge must be directed away from electrical components or where it might be a hazard to the user.
7.4The pressure gauge indicates the system pressure which must be maintained.
7.5The 8 litre expansion vessel is charged to 0.5 bar and is suitable for a static head of 5 metres (17.5ft). The pressure can be increased if the static head is greater than 5 metres (17.5ft).
7.6With an initial system pressure of 0.5 bar, a system capacity of up to 100 litres can be accommodated. For system capacities greater than this an extra expansion vessel must be fitted. Refer to BS 7074 Pt. 1 for more information. The charge pressure can be increased but with a consequent decrease in system volume.
7.7The filling point must be at low level. See Fig. 4.
7.8Water loss must be replaced. See Fig 4. The connection should be made in the central heating return as close to the appliance as possible.
7.9Repeated venting loses water from the system. It is essential that this water is replaced and the system pressure maintained.
7.10Connections to the mains water supply must not be made without the authority of the local Water Company.
7.11The pump is set at maximum and must not be adjusted.
7.12Connections in the system must sustain a pressure of up to 3 bar.
7.13Radiator valves must conform to BS 2767:10.
7.14Other valves used should conform to the requirements of BS 1010.
7.15The appliance is fitted with a fixed internal
8. Open Vent System
The appliance is NOT suitable for connection to an open vented system.
Fig. 4. Sealed primary water system.
Radiator valve
Lockshield valve
NOTE: A drain cock should be installed at the lowest point of the heating circuit and beneath the appliance.
Heating return Heating flow
Automatic air vent
Expansion | Mains cold | |
water | ||
vessel | ||
|
Hot water out
British Standard stop valve. 
Fixed spindle type
Water main
Filling Loop Detail
Heating Return
Valve Valve
Hose union 
Stop cock
Test cock | Temporary Hose |
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