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Pressure reducing valve
1. Isolate the cold water supply and open a
ground floor cold tap.
2. Unscrew the pressure reducing cartridge
3. Clean the filter mesh and the cartridge
under running water.
4. Replace cartridge ensuring that strainer is
correctly located and reassemble the unit.
Pressure Reducing Valve cartridge and
strainer Part No. REDC355030 - 3 Bar.
Expansion relief cartridge
1. Isolate the cold water supply and open a
ground floor cold tap.
2. Unscrew blue expansion relief headwork
from valve body.
3. Clean valve seat face and seating - do not
scratch or damage either seat face or seating.
4. Refit in reverse order. Do not overtighten
Expansion valve cartridge and seat Part
No. 214005 6.0 Bar.
Spare parts
MAINTENANCE
Pressure reducing valve
Cartridge - Part No.
REDC 355030 - 3 bar
Expansion valve
(Cartridge and seat)
Part No.
214005
6.0 Bar
Expansion valve
6.0 Bar - Part No.
PREL355030
Safety Cut-out
1. The safety cut-out operates if:
a. Wiring is incorrect.
b. The immersion heater thermostat or cylinder thermostat fails.
c. Thermostat is set too high.
2. Remember before resetting the safety cut-out or altering the thermostat setting, isolate electrical supply
to the unit prior to removal of the electrical box lid.
3. Reduce thermostat setting and press the reset button. After adjustments are completed, ensure the lid
to the electrical box is replaced correctly and the retaining screw is fitted.
4. If still out of operation, contact installer.
It is a condition of the guarantee that annually a competent person:
(a) Inspects and cleans the line strainer.
(b) Checks the operation of the expansion relief valve and temperature & pressure relief valve.
(c) Recommissions the cylinder in accordance with the instructions above.
Corrosion resistance
Stainless steel is naturally corrosion resistant to mains water supply. No specific maintenance is required
to maintain this resistance. Please see guarantee terms for permissable water content. Please note: OSO
cylinders are not guaranteed for use with a private water supply.
The immersion heater can be removed to provide visual inspection access to the cylinder.
Cold or tepid water
discharge from tundish -
The tundish should be installed away from electrical devices.
1. Close cold water supply valve
2. Open a hot tap.
3. Repressurise the expansion vessel air charge to its set level.
4. Close hot tap
5. Open the cold water supply valve
Hot water
discharge from tundish
This indicates a malfunction of a thermal cut-out, operating thermostat or the combined temperature and
pressure relief valve. Turn off the electrical supply to the immersion heater and also isolate an indirect unit
from the boiler. Contact the installer or competent engineer.
SAFETY AND MAINTENANCE
RECOMMISSIONING INSTRUCTIONS
Draining/flushing
1. Turn off mains supply.
2. Connect hose pipe to drain cock at base of cylinder.
3. Open hot tap. Open drain valve and open temperature & pressure relief valve.
4. Allow to drain. Follow commissioning instructions (above) to refill.
