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Externa 30 O
Cod. 3540T540 - 04/2009 (Rev. 00)
Pressure relief valve
Externa 30 O
incorporates a pressure relief valve discharging at 300 kPa.
The discharge of the pressure relief valve must be con nected to a collection container, to avoid
water spill ing onto the ground in the event of over-pres sure in the central heating circuit. The
manufacturer of the boiler will not be held liable if this warn ing is not heeded, and the discharge
valve in tervenes and floods the room.
Characteristics of the system water
In the case of water with hardness above 25 French degrees, the water should be suitably treated,
to avoid any deposits in the boiler caused by hard water, or corrosion caused by aggressive water. It
should also be remembered that even minor deposits measuring just a few millimetres thick can cause,
due to their low thermal conductivity, significant overheating of the walls of the boiler, with consequent
serious problems.
The water must always be treated in the case of very large systems (with high water capacity) or sy-
stems with the frequent inlet of recovered water. If, in these cases, the system needs to be partially or
completely emptied, it must be refilled with treated water.
Filling the boiler and the system
The boiler is fitted with a ball cock for manually filling the central heating system. The filling pressure,
when the system is cold, must be around 1 bar. If the pressure drops during operation (due to the eva-
poration of the gas dissolved in the water) to a value lower than the minimum described above, the User
must restore the initial value using the filling cock. For correct boiler operation, the pressure, when hot,
must be around 1,5÷2 bar. Once the operation is completed, always close the filling cock.
2.4 Gas connection
Before making the connections, check that the appliance is configured for operation with the
type of fuel available, and carefully clean all the gas pipes in the system, to remove any residues
that may affect the correct operation of the boiler.
The gas connections must be made at gas inlet (see fig. 3 - key 3), with a rigid metal pipe, or a stainless
steel flexible continuous-wall pipe, fitting a gas cock between the system and the boiler. Before instal-
lation, mount the threaded adapter ISO 7-1 contained in boiler package, as shown in fig. 3b. Check that
all the gas connections for tightness.
The capacity of the gas counter must be sufficient for the simultaneous use of all the connected appliances.
The diameter of the gas pipe, which leaves the boiler, does not necessarily determine the choice of the
diameter of the pipe used between the appliance and the gas counter; this must be chosen according
to its length and the pressure drop, according to the standards in force.
Do not use the gas pipes as the earth for electrical appliances.
2.5 Electrical connections
Connection to the mains power supply
The boiler should be connected to a single-phase, 240 Volt-50 Hz electrical line.
The electrical safety of the appliance is ensured only when the appliance is correctly connected
to an effective earth system, as prescribed by the safety standards in force. Have professionally
qualified personnel check the efficiency and the rating of the earth system. The manufacturer
is not liable for any damage caused by the appliance not being correctly earthed. In addition,
make sure that the electrical system is adequately rated for the maximum power absorbed by
the appliance, indicated on the boiler rating plate, and in particular that the cross-section of the
wires is suitable for the power absorbed by the appliance.
The boiler is pre-wired and fitted with a cable for connection to the electrical line. The connections to
the mains supply must be made using a fixed connection, featuring a two-pole switch with a contact
