13
6.0 System Details
© Baxi Heating UK Ltd 2013
Fig. 4
Fig. 6
Stop
Valve
Double
Check
Valve
DHW
Mains
Inlet
CH
Return
Temporary
Loop
Pressure Relief Valve
Discharge Pipe
Stop
Valve
Fig. 5
6.4 System Filling and Pressurising
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:
for GB: Guidance G24.2 and recommendation R24.2 of the
Water Regulations Guide.
for IE: 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.
6.5 Expansion Vessel (Central Heating only)
1. The appliance expansion vessel is pre-charged to 0.5 bar.
Therefore, the minimum cold fill pressure is 0.5 bar. The
vessel is suitable for correct operation for system capacities
up to 100 litres (32 kW model - 155 litres). For greater
system capacities an additional expansion vessel must be
fitted. For GB 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. 6)
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
15mm 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 (Fig. 6a).
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).
5. A boiler discharge pump is available, part no. 720648301.
This pump will dispose of both condensate & high
temperature water from the relief valve. It has a maximum
head of 5 metres.
Control Box removed
for clarity
Fig. 6a
The end of the pipe should
terminate facing down and
towards the wall
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