Technical data

6.0 System Details – page 10
Fig. 3
Fig. 4
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. The filling method adopted must be in accordance with
all relevant water supply bye-laws and use approved
equipment.
3. Your attention is drawn to: IRN 302 and Byelaw 14.
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 (Fig. 3).
6.6 Expansion Vessel
(Central Heating only)
1. The appliance expansion vessel is pre-charged to 1 bar
(10 lb/in²). Therefore, the minimum cold fill pressure is
1 bar. The vessel is suitable for correct operation for
system capacities up to 125 litres (27.5gal). For greater
system capacities an additional expansion vessel must
be fitted - refer to BS 7074 Pt 1.
6.7 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.