DOMINA 80 E
36
3.13 Electrical connection
The boiler must be connected to a single phase 230 V 50 Hz electricity supply with a 3 A max. fuse and
a bipolar switch with contact opening of at least 3 mm fitted between the boiler and the electricity supply.
The boiler must always be connected to an efficient earth installation. Under the electrical box, there is
a 3 pole terminal board for connecting the boiler to the mains (230 V 50 Hz) and a 2 pole board for
connecting a room thermostat (RT). To connect, undo the screws fixing the terminal board box and
connect the wires, ensuring correct polarity of the terminals. It should be noted that there is low voltage
(24 V) between the room thermostat contacts.
When the boiler is connected to an electricity main, it is essential TO OBSERVE CORRECT POLARITIES
(LIVE: brown cable, NEUTRAL: blue cable, EARTH: yellow-green cable)
.
All wiring must conform to current I.E.E. regulations.
Note
: If the power supply cable has to be replaced, use “0.75mm (24/0.20) cable only to BS6500 with a
maximum external diameter of 8 mm.
Note -
When connecting a room thermostat or external timer, do not link the power supply of these
devices to the switching contacts. The switch contacts must be voltage free. Any mains powered devices
must utilise mains power solely to drive the timer motor.
Applying mains voltage to the switch contacts will irreparably damage the circuit board.
Although this boiler can also be used without a room thermostat, you are recommended to install one for
the following reasons:
Greater comfort conditions due to more accurate control of room temperature.
Greater energy savings.
3.14 Differential air pressure switch
(fig. 2 - part 43)
The differential air pressure switch is a safety device which allows the main burner to ignite only after
having verified that the fan is working correctly. If the difference in pressure between the flue gas
discharge pipe and the air intake pipe is not at least equal to the minimum pressure switch calibration
value, the pressure switch contacts do not close and the gas valve is thus prevented from opening.
In addition, the electrical circuit of the boiler is designed so that if for any reason the air pressure switch
contacts remain closed when the fan stops, the burner will not start up again.
3.15 Checks
Fill the central heating system as described previously (3.11) and check there are no leaks in the domestic
hot water and boiler water circuits. Check that there are no gas leaks on the boiler or the supply to the
boiler. Also check that the electrical connections are correct.
3.16 Installing a room thermostat (72)
(fig. 48)
To connect the thermostat:
Open the electrical box on the base of the appliance and remove the “jumper cable” between terminals
4 and 5.
Connect the room thermostat (72) as shown in figure 48.