Technical data

13
6.0 System Details
© Baxi Heating UK Ltd 2011
Fig. 3
Filling Loop for
Sealed Systems
Fig. 4
Stop
Valve
Double
Check
Valve
Mains
Cold
Water
CH
Return
Temporary
Hose
Pressure Relief Valve
Discharge Pipe
Stop
Valve
6.4 System Filling and Pressurising
Sealed Systems
1. A filling point connection on the central heating return
pipework must be provided to facilitate initial filling and
pressurising and also any subsequent water loss
replacement/refilling.
2. The filling method adopted must be in accordance with all
relevant water supply regulations and use approved equipment.
3. Your attention is drawn to the current edition of I.S. 813
“Domestic Gas Installations”.
4. The sealed primary circuits may be filled or replenished by
means of a temporary connection between the circuit and a
supply pipe, provided a ‘Listed’ double check valve or some
other no less effective backflow prevention device is
permanently connected at the inlet to the circuit and the
temporary connection is removed after use.
‘Semi - Sealed’ Systems
1. ‘Semi - Sealed’ systems require the use of a suitable header
tank and ball cock arrangement to charge and provide
subsequent replenishment of the system.
2. The tank must be placed to provide sufficient head in order
to ensure a minimum system pressure of 0.2 bar.
3. A suitable non - return valve must be fitted in the pipework
between the header tank and heating system.
6.5 Expansion Vessel
1. The appliance expansion vessel is pre-charged to 0.5 bar.
The vessel is suitable for correct operation for system
capacities up to 125 litres. For greater system capacities an
additional expansion vessel must be fitted. Refer to BS 7074
Pt 1. For IE, the current edition of I.S. 813 “Domestic Gas
Installations”.
6.6 Safety Pressure Relief Valve (Fig. 4)
1. The pressure relief valve is set at 3 bar, therefore all
pipework, fittings, etc. should be suitable for pressures in
excess of 3 bar and temperature in excess of 100°C.
2. The pressure relief discharge pipe should be not less than
1/2” dia, run continuously downward, and discharge outside
the building, preferably over a drain. It should be routed in such
a manner that no hazard occurs to occupants or causes
damage to wiring or electrical components. The end of the
pipe should terminate facing down and towards the wall.
3. The discharge must not be above a window, entrance or
other public access. Consideration must be given to the
possibility that boiling water/steam could discharge from the
pipe.
4, A remote relief valve kit is available to enable the boiler to
be installed in cellars or similar locations below outside ground
level (kit no. 5121379).
Fig. 3a
‘Semi-Sealed’
System
CH
Return
Header Tank
Non-Return
Valve
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