5
4. Commissioning and filling up
5. Draining & flushing out the system
4.1 Commissioning
4.1.1
Check all connections for tightness.
4.1.2
Open hot water tap furthest away from the OSO water heater. 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.
4.1.3
Check all water connections for leaks and rectify if necessary.
Manually operate Expansion relief valve 4 (see 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.
Manually operate Temperature and Pressure Relief Valve 5 (see page 3) to ensure free water flow through discharge
pipe (Turn knob counter-clockwise).
Switch electrical power on.
5.1 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 12 (see page 3) at base of cylinder.
The unit will drain. Draining process may be speeded up by opening the temperature and pressure relief valve. An
internal ø18 mm hose can be applied to lead the water to a gully, sink or similar.
5.2 System flushing
This 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 flow rate. Close
the taps and follow draining procedure (above).
pipework must have continuous fall and discharge in a safe, visible position. If any doubt, refer to Building Regula
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tion G3.
Discharge pipe must be dedicated to the cylinder and must not be used for any other purpose.
3.6 Primary Flow and Return and Motorised valve
3.6.1
The boiler primary flow and return connections should be made connections 1 & 2. The motorized valve can
be connected to either the primary flow or return pipe. The primary flow and return fittings are 3/4’’ BSP female.
The valve has 22mm x copper connections. The direction of primary flow in the coil is bottom to top. The maximum
operating temperature of the primary flow would typically be 82°C.
For electrical connection of the motorised valve and immersion heater, please read Electrical Installation Instruc
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tions. (Page 5).
