Safety And Servicing - OSO Super S Installation Manual

7. Safety and Servicing

Maintenance must be carried out by a competent person.
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.
Intermittent or slow discharge from tundish
1. Turn off the electrical supply to the immersion heaters.
2. Turn off cold water supply valve.
3. Open a hot tap.
4. Turn the knob on the Temperature and Pressure Relief Valve (5) to the left and hold in this position for
thirty seconds.
5. Attach a foot pump with a schraeder (car type) valve to the expansion vessel.
6. Pump up to 3.5 bar
7. Open cold water supply valve.
8. When water flows through open tap, close tap.
9 Turn on electrical supply to the immersion heaters.
Continous very 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.
Expansion vessel maintenance
The expansion vessels do not require annual maintenance and should not be tampered with unless an intermittent or
slow discharge from the tundish occurs when water is being heated. In this situation, maintenance must be carried out
by competent person and the precharge pressure must be restored to the original value. An annual visual inspection
is recommended. Important: To check the precharge the expansion vessel must be completely empty of water. If the
precharge pressure is different from the value shown on the label it must be restored to the original value.
Do not remove expansion vessel without depressurizing the cylinder and draining 10 litres of water from the drain valve at
the base of the cylinder.
Guarantee
Cylinder should be serviced annually and benchmark logbook should be updated in order to validate guarantee. Logbook
and service records act as guarantee document. For terms of guarantee please see Benchmark logbook on page 14.
Servicing Procedure:
Line strainer
1. Isolate cold water supply.
2. Unscrew the retaining nut of the valve. The strainer mesh can be removed.
3. Clean the mesh under running water.
4. Replace mesh and reassemble valve.
Expansion relief valve
Ensure that expansion relief valve works by manually opening to discharge water to tundish.
Temperature and Pressure relief valve
Ensure that Temperature & Pressure Relief valve works by manually opening to discharge water to tundish.
Combination valve
The combination valve can be separated into two sections by disconnecting the compression fitting in the middle. The
entire valve can be removed by unscrewing from the top connection. When refitting, the valve does not tighten, the seal is
created by a double O-ring. To create the seal, the valve should be wound down until it will not go any further, then wound
back up less than one full turn to point in the desired direction.
Drain cock
To remove drain cock, drain cylinder fully. When cylinder has drained, unscrew rear locking ring behind drain cock (turn
clockwise). Pull drain cock off. Reverse procedure to refit drain cock. Locking ring only needs to be hand tight, seal comes
from double o-ring.
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