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Fig. 4
The end of the pipe should
terminate facing down and
towards the wall
Fig. 6a
Pressure Relief Valve
Discharge Pipe
14
© Baxi Heating UK Ltd 2017
Double
Stop
Check
Valve
Valve
Temporary
DHW
Loop
Mains
Inlet
Filling Loop
Connections
Control Box removed
for clarity
Fig. 6
6.0 System Details
6.5
System Filling and Pressurising
1. A filling point connection on the central heating return
Stop
pipework must be provided to facilitate initial filling and
Valve
pressurising and also any subsequent water loss
replacement/refilling.
2. A filling loop that connects to the primary return & cold
mains inlet valves is available as an accessory. Follow the
instructions provided with it.
CH
Return
3. The filling method adopted must be in accordance with all
relevant water supply regulations and use approved equipment.
4. 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".
5. The sealed primary circuits may be filled or replenished by
Fig. 5
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.
6.6
Expansion Vessel (Central Heating only)
1. The appliance expansion vessel is pre-charged to 1 bar.
Therefore, the minimum cold fill pressure is 1 bar. The vessel is
suitable for correct operation for system capacities up to 100
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".
6.7
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. If it is anticipated that any
part of the pipe may be subject to freezing it should be suitably
insulated. 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.
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