10
4. ELECTRICAL INSTALLATION
4.1 Immersion heaters
Power to immersion heaters should not be switched
on until the unit is filled with water. All units are fit-
ted with 2 no. 3 kW immersion heaters except SX
120 which has 1 no. 3kW immersion heater. Immer-
sion heaters must be wired through the factory fit-
ted thermostat and thermal cut-out according to
diagram on the reverse of the electrical box cover.
Alternative thermostats should not be used, regula-
tions require immersion heaters on unvented cylin-
ders to be connected with a thermal cut-out.
4.2 Wiring of immersion heaters & thermostats
Follow the wiring instructions connecting the line,
neutral and earth as indicated. A dedicated perma-
nent supply complying with current IET regulations
should be used, and each circuit must be protected
by a suitable fuse and double pole isolating switch
with a contact separation of at least 3 mm in both
poles. All electrical wiring should be carried out by
a competent electrician and be in accordance with
the latest Edition of IET (formerly IEE) Wiring Regu-
lations.
Use only a suitable heat resistant round cable with
a minimum rating of 90°C, for example H05V2V2-F
(309-Y). All internal wiring is factory mounted.
Upper immersion thermostat (ThermODisc)
The recommended screw torque is 0.2 kp (2.0Nm).
End terminal fork width must not exceed 10 mm,
see illustration.
A safety cut-out is also incorporated within the
upper thermostat and will operate at 85°C ± 3°C.
Should this happen, check reasons for thermal cut-
out button being released and when satisified press
the reset button. Important: Before resetting the
safety cut-out or altering the thermostat setting,
isolate electrical supply to the unit prior to removal
of the lid. Ensure the lid to the electrical box is re-
placed correctly and the retaining screw is fitted.
Bottom immersion thermostat:
The 80323 thermostat for 120 litre and 80322 ther-
mostat for all other sizes with embedded iQ Smart
Technology has been designed for compliance with
European regulations newly introduced for Electric
Storage Water Heater (ESWH) efficiency and en-
ergy saving. The thermostat has a wide range of
configurations to provide the maximum flexibility
with the OSO Sole 109 blending valve. The 80322/3
configuration maximizes efficiency improvement
and provides all mandatory smart control features.
RESET
RE
SET
M2
1
2
3
4
THERM-O-DISC
40°C
70°C
60°C
50°C
1
2
COTHERM
iQuaFlex
A
T60
220-240V~ 14A
B
V
D E
S
L
L
N
N
Upper
Immersion
Bottom
Immersion
and iQ
smart ther-
mostat
Cable
clamp
Immersion
thermostat
MAX
10 mm
Fork for upper immersion thermostat (ThermODisc)
