21
INSTALLATION
combination boiler -
Installation and Servicing
2 9 ELECTRICAL CONNECTIONS
Connection must be made in a way that allows complete
isolation of the electrical supply such as a double pole
switch having a 3mm (1/8") contact separation in both
poles, serving only the boiler and system controls. The
means of isolation must be accessible to the user after
installation.
All boilers are provided complete with 1 m supply cable. In
case the cable is not long enough a suitable junction must
be used
WARNING
. This appliance MUST be earthed.
A mains supply of 230 V ~ 50 Hz is required.
The fuse rating should be 3A.
Wiring external to the boiler MUST be in accordance with the
current I.E.E. (BS7671) Wiring Regulations and any local
regulations.
All external controls and wiring must be suitable for mains
voltage.
Wiring should be 3 core PVC insulated cable, not less than
0.75 mm
2
(24 x 0.2mm), and to BS 6500 Table 16.
3 0 EXTERNAL ELECTRICAL CONTROLS
Wiring External to the Boiler
The fuse rating should be 3A.
Wiring external to the boiler MUST be in accordance with the
current I.E.E. (BS.7671) Wiring Regulations and any local
regulations.
Frost Protection
The boiler is provided with a built in frost protection electronic
system.
When the temperature detected by the CH sensor is below
5°C , the boiler is put into operation till the CH sensor detects
a temperature off 15°C.
The frost protection electronic system is operating only if the
electrical supply and gas are On.
Room Thermostat
The room thermostat is placed onto the 24 Vdc circuit.
Do not
connect any external supply to the room thermostat: this
will permanently damage the PCB (see A).
Designation of the terminals will vary but the thermostat
manufacturers' leaflets will give full details.
Diagrams A
shows application of boilers fitted with room
thermostat and integral programmer.
Diagrams B
shows application of boilers fitted with room
thermostat, external programmer and remote frost
thermostat.
Frost Thermostat
If any part of the pipework is in danger of damage due to frost
a frost thermostat may be necessary, preferably fitted on the
return pipework.
To facilitate the fitting of a frost thermostat the integral
programmer must be unplugged from the PCB.
An independant programmer must be fitted. This must have
volt free contacts for switching the boiler on and off according
to the timer settings.
The programmer room thermostat and frost thermostat must
then be connected as shown in the wiring diagram B.
1
2
3
Room ‘stat
TA - Plug
A9 - Plug
Time controls
A
Programmer
B
1
2
3
Room ‘stat
TA - Plug
Frost ‘stat
Programmer
L
N
INSTALLATION
