Commissioning And Filling Up; Electrical Connection - OSO Super S Installation Manual

5. Commissioning and filling up

1. Check all connections for tightness. Open hot water tap furthest away from the OSO water heater.
2. Open the mains stop cock to fill the water heater. When water flows evenly from tap, allow to run for a few minutes
to flush through any dirt, swarf or residue, then close the tap. Open successive hot taps to purge any remaining air.
3. Check all water connections for leaks and rectify if necessary.
4. Manually operate Expansion relief valve B (see fig. 1 on page 3) to ensure free water flow through discharge pipe
by turning knob counter-clockwise. To close continue to turn counter-clockwise until the valve shuts.
5. Manually operate Temperature and Pressure Relief Valve C (see fig. 1 on page 3) to ensure free water flow
through discharge pipe (Turn knob counter-clockwise).
6. Switch electrical power on.
7. Replace the cylinder lid – this is important as the lid prevents heat loss from the cylinder and combination valve,
conserving valuable energy. Do not place heavy objects on the lid.
Draining & flushing out the system.
Draining.
Switch off the electrical power (Important to avoid damage to element). Isolate boiler from OSO unit. Turn off the cold
water supply valve. Open hot water tap. Open drain at base of cylinder. The unit will drain. Draining process may be
speeded up by opening the temperature and pressure relief valve.
System flushing will not be necessary under normal circumstances as the line strainer will prevent ingress of foreign
materials, however if flushing is required, run at least 50 litres of water from the cylinder at the highest possible flowrate.
Close the taps and follow draining procedure.
6. Electrical installation
6.1 Immersion heaters
Power to immersion heaters should not be switched on until the unit is filled with water. All indirect units are fitted with
one 3 kW immersion heater which is located behind the electrical box. With the exception of the 120 litre all direct units
have two 3 kW immersion heaters. Immersion heaters must be wired through the factory fitted thermostat and thermal
cut-out according to diagram on the reverse of the electrical box cover. Alternative thermostats should not be used,
regulations require immersion heaters on unvented cylinders to be connected with a thermal cut-out.
Direct units
Wiring instructions for the immersion heaters are located on the reverse side of the lid. Follow the wiring instructions
connecting the live, neutral and earth as indicated. 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.
The presence of a blending valve in the main hot water valve means that the direct thermostats are factory set to 70°C.
Water will not be delivered to the taps higher than 60°C. This increases the amount of usable hot water available from
the cylinder.
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, 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 replaced correctly and the retaining screw is fitted.
The lower immersion heater should be connected to the off peak supply (if available) whilst the top immersion heater
can be connected to the day tariff. The immersion heater can be connected to the mains supply through a water heater
controller (Contact your local electricity company if in doubt).
Indirect Units
Motorised valve: To comply with regulations governing the installation of indirect unvented cylinders, a motorised valve
must be fitted in the primary pipework. 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 electrical box. The unit should be installed
on an "S" or "Y" plan system. Please follow the wiring instructions carefully.
The working thermostat which controls the temperature of the domestic hot water (see fig. 2) 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. If using a 6-wire 28mm
or 1" BSP V4043H on either circuit the white wire is not needed and must be made electrically safe.
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.
- all wiring must conform to current IEE regulations
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