6.0 System Details
14
© Baxi Heating UK Limited 2005
6.2
System Control
1. The boiler is designed for use in a heating system that
incorporates external controls, i.e. a minimum of a timer
device.
2. Suitable timer kits are available as optional extras.
6.3
System Filling and Pressurising
(Fig. 3)
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.
5. To aid removal of air from the system whilst filling,
move the diverter valve to the CH position by using the
installer parameters (see Section 10.4).
6.4
Expansion Vessel - CH only
(Fig. 4)
1. The appliance expansion vessel is pre-charged to 1 bar
(14.5 lb/in
2
). 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.
For GB refer to BS 7074 Pt 1. For IE, the current edition
of I.S. 813 “Domestic Gas Installations”.
6.5
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 not be 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
Stop
Valve
Double
Check
Valve
DHW
Mains
Inlet
CH
Return
Temporary
Hose
Pressure Relief
Valve
Expansion Vessel
removed for clarity
Fig. 4
Expansion Vessel
Stop
Valve
