Heatrae Sadia Multipoint ECO 100L V 3kW Installation, Operation And Maintenance Manual page 25

Descaling immersion heater
CAUTION
Be careful when removing the immersion
heater as some water will be left in bottom of
appliance.
DO NOT use a sharp implement as damage to
the element surface could be caused.
DO NOT scrape element clean.
Turn off the mains water supply and isolate the
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electrical power supply to the appliance.
Attach a hosepipe to the drain cock having sufficient
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length to take water to a suitable discharge point
below the level of the appliance. See typical
installation (see Figure 6, page 11).
Open a hot tap close to the appliance and open
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drain cock to drain the appliance.
When empty, Open the cover to the immersion
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heater housing. Remove the securing screw then
release the cover by carefully inserting a flat bladed
screwdriver into the slots around the cover and
gently levering outwards until the catches release
(see Figure 10, page 25).
Disconnect wiring from immersion heater terminals.
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Carefully remove the thermostat and thermal cut-out
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capilliary sensor from the pocket on the immersion
heater.
Place a suitable receptacle beneath the immersion
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heater to collect any water left in the appliance.
Unscrew immersion heater bolts and remove
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immersion heater from the water heater.
NOTE: Over time the immersion heater gasket may
become stuck to the mating surface. To break the seal
there is a seperate threaded hole in the plate. Screw one
of the removed bolts into this hole to help remove element.
Carefully remove any scale from the surface of
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the element. Remove any loose scale from the
appliance interior.
Ensure sealing surfaces are clean and seals are
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undamaged, if in doubt fit a new gasket.
Refit immersion heater ensuring correct orientation.
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This is achieved by locating the immersion heater
plate over the threaded stud first. Only one hole on
the immersion plate fits this stud.
Tighten bolts in a diagonal pattern, starting with the
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M6 Nut.
Fill unit with water and check for leaks.
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Refit the combined thermostat and thermal cut-out
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capillary sensor, (these two parts are joined), into
pocket on the immersion heater, ensure they are
pushed fully into the pocket and the capillary tubes
are not kinked or damaged.
Reconnect wires from the thermostat onto the
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element, ensuring that the terminals are correctly
engaged.
Reconnect the earth wires to the earth stud.
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Refill the appliance. When water flows from the hot
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tap allow to run for a short while to purge any air
and flush through the pipework. Open successive
hot taps served by the appliance to purge any air.
With all hot outlets closed check all joints for leaks.
Close immersion heater housing cover ensuring
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the catches are pushed fully home until they
"snap" into place. Secure by replacing the screw
previously removed.
Turn on electric power supply. Allow to heat.
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Expansion vessel charge pressure
CAUTION
DO NOT OVER-CHARGE
VESSEL
Remove the dust cap on top of the vessel.
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De-pressurise the system by turning the mains
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cold water supply off and then opening a hot tap
served by the appliance.
Check the charge pressure using a tyre
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gauge. The pressure (with system de-pressurised)
should be 0.35MPa (3.5 bar).
If it is lower than the required setting it should be re-
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charged using a tyre pump (Schrader valve type).
Re-check the pressure and when correct replace
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the dust cap.
Figure 10: Cover removal
EXPANSION
pressure
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