Immersion heaters
All units are fitted with one immersion heater which is located behind the lower electrical box.
Wiring instructions for the immersion heater is located on the reverse side of the lower lid. Follow the
wiring instructions connecting the live, neutral and earth as indicated. The electrical connection to the
immersion heater must conform to current IEE wiring regulations. The unit must be permanently
connected to the electrical supply through a double-pole linked switch with a minimum break capacity
of 13 amps. All internal wiring is factory mounted. Each immersion heater has a working thermostat
adjustable between 40°C - 70°C. A safety cut-out is also incorporated within the thermostat and will
operate at 85°C ± 3°C. Should this happen, 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 replaced correctly and the
retaining screw is fitted.
Indirect Units upper coil
Motorised valve
To comply with regulations governing the installation of indirect unvented cylinders, a motorised valve
must be fitted in the primary flow. Your OSO unit has been supplied with a two port motorised valve,
which will act as a positive energy cut-out should the safety cut-out operate. The motorised valve will
also control the temperature of the domestic stored water via the cylinder thermostat, which is located
in the upper electrical box. The unit should be installed on an “S” or “Y” plan system. Cylinder
temperature control can also be achieved via the solar thermostat when the boiler is not operational.
Please follow the instructions carefully.
All electrical connections must conform to current IEE wiring
regulations. The working thermostat is adjustable between 40°C - 70°C. A safety cut-out is also
incorporated within the thermostat and will operate at 85°C ± 3°C. Should the safety cut-out be brought
into operation, the motorised valve will operate and close down the primary flow to the cylinder. To
reset the safety cut-out and the motorised valve the reset button must be pressed in (see fig.4 page 9).
Lower (Solar) coil
Heat sources to unvented hot water cylinders must be controlled by a thermal cut-out as well as a
thermostat. The Oso Solarcyl is supplied both with bosses for solar sensor pockets and the pockets
themselves.
The top half of the thermostats fitted to the cylinder is a thermal cut-out. The solar controller (not
supplied) and solar sensor point should be wired through the Oso thermal cut-out.
Please note that the direction of flow in the solar coil is reversed compared to the boiler coil. If the
cylinder is not being used for solar use, follow the directions for the upper coil.
OSO Hotwater (UK) Limited can not be responsible if alternative wiring plans are used.
Important: Before resetting the safety cut-out or altering the thermostat setting isolate electrical supply
to the unit before removal of the lid.
ELECTRICAL INSTALLATION
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