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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
`
electrical supply to the appliance.
Attach a hosepipe to the drain cock having sufficient
`
length to take water to a suitable discharge point
below the level of the appliance.
Open a hot tap close to the appliance and open
`
drain cock to drain the appliance.
When empty, open the cover to the immersion
`
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 18).
Disconnect wiring from immersion heater terminals.
`
Carefully remove the thermostat and thermal cut-out
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capilliary sensors from the pocket on the immersion
heater.
Place a suitable receptacle beneath the immersion
`
heater to collect any water left in the appliance.
Unscrew immersion heater bolts and remove
`
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
`
the element. Remove any loose scale from the
appliance interior.
Ensure sealing surfaces are clean and seals are
`
undamaged, if in doubt fit a new gasket.
Replace
immersion
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orientation. One of the bolt holes uses a larger bolt
to ensure the correct orientation.
Tighten bolts.
`
Fill unit with water and check for leaks.
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Replace thermostat and thermal cut-out capillary
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sensors into pocket on the immersion heater,
ensure that the thermostat is inserted first followed
by the cut-out (see figure 2, page 7 to identify).
Ensure they are pushed fully into the pocket and
the capillary tubes are not kinked or damaged.
Reconnect wires from the thermostat onto element,
`
ensuring that the terminals are correctly engaged.
Reconnect the earth wires to the earth stud.
`
Refill the appliance. When water issues from the
`
hot 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.
18
heater
ensuring
correct
With all hot outlets closed cheeck all joints for leaks.
Close immersion heater housing cover ensuring
`
the catches are pushed fully home until they
"snap" into place. Secure by replacing the screw
previously removed.
Expansion vessel charge pressure
CAUTION
DO NOT OVER-CHARGE EXPANSION
VESSEL
Remove the dust cap on top of the vessel.
`
De-pressurise the system by turning the mains
`
supply off and then opening a hot tap served by
the appliance.
Check the charge pressure using a tyre
`
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-
`
charged using a tyre pump (Schrader valve type).
Re-check the pressure and when correct replace
`
the dust cap.
Figure 10: Cover removal
pressure
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