Descaling; Safety Valves - Heatrae Sadia Multipoint 30 Installation And User Instructions Manual

7.10 Setting the "hot" position:
Rotate the thermostat knob to mid way through the hot graduated range (red
graphic). Follow the procedure detailed above, however in this case the knob
should be held in the "hot" position previously set. When the terminal cover has
been refitted the thermostat will be locked in the "hot" position. This position is
recommended when using the heater in conjunction with a thermostatic blending
valve.
8.0 MAINTENANCE - DESCALING
Little maintenance is required, however in hard water areas the unit will require
periodic descaling to ensure efficient operation. To descale the unit:
8.1 Switch off and disconnect the electrical supply. Turn off the water supply to the
unit.
8.2 Open a hot tap to relieve any system pressure. Empty unit by opening the drain
cock in the inlet pipework.
8.3 Remove the terminal cover by using a large flat bladed screwdriver to depress the
4 snap lugs located in the 4 rectangular depressions on the bottom cover.
8.4 Disconnect the electrical terminations to the element. Disconnect earth links to
the earthing stud. Withdraw the thermostat and thermal cut-out capillary tubes
from the pocket on the element plate.
8.5 Remove the element plate assembly by unscrewing the five securing screws,
tapped jacking holes are provided (NOTE: a quantity of water may still be
present in the container, it is recommended that a container be placed under the
unit to collect any spillage). Remove any loose scale from the container. Carefully
clean off any scale from the element and thermostat pocket. DO NOT clean scale
from interior container walls.
8.6 Re-assemble the element plate assembly fitting a new sealing gasket. Rewire the
unit with reference to the Wiring Diagrams.
8.7 Re-commission the unit following the INSTALLATION and COMMISSIONING
instructions.
9.0 MAINTENANCE - SAFETY VALVES
9.1 The Temperature/Pressure Relief Valve and the Pressure (expansion) Relief
Valve should be regularly checked. Manually operate the valves by either
twisting the cap or lifting the lever. Ensure water flows freely from the valve(s)
and through the discharge pipes (NOTE: the water discharged may be very hot).
Ensure the valve(s) reseat correctly when released.
9.2 Clean the strainer incorporated in the Pressure Reducing Valve. To inspect and
clean the strainer turn off the mains water supply to the heater and open a hot
tap to relieve the system pressure. Unscrew the black cap from the Pressure
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