Baxi Megaflo System HE IE Series Installation & Servicing Instructions Manual page 15

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Fig. 3a 'Semi-Sealed' System
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
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. 4)