Technical data

15
6.0 System Detail
© Baxi Heating UK Ltd 2007
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
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. for GB refer to
BS 7074 Pt 1. For IE, the current edition of I.S. 813
“Domestic Gas Installations”.
6.6 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.
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.
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.
Fig. 3
Fig. 4
Stop
Valve
Double
Check
Valve
Mains
Cold
Water
CH
Return
Temporary
Hose
Pressure Relief Valve
Discharge Pipe
Stop
Valve