14
6.0 System Details
© Baxi Heating UK Ltd 2016
Fig. 4
Fig. 6
Pressure Relief Valve
Discharge Pipe
Fig. 5
6.5
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. A filling loop is supplied with the boiler. Follow the
instructions provided with it.
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
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 1.0 bar.
Therefore, the minimum cold fill pressure is 1.0 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. 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. 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
Filling Loop
Connections
Stop
Valve
Double
Check
Valve
DHW
Mains
Inlet
CH
Return
Temporary
Loop
Stop
Valve
Fig. 6a
The end of the pipe should
terminate facing down and
towards the wall