Heatrae Sadia MEGAflo Installation Manual page 28

8.5 DESCALING IMMERSION HEATER(S)
Open the cover(s) to the immersion heater housing(s) and disconnect wiring from immersion
heater(s). Remove the thermostat by carefully pulling outwards from the immersion heater. Un-
screw immersion heater backnut(s) and remove immersion heater from the unit. A key spanner is
supplied with the Megaflo unit for easy removal/tightening of the immersion heater(s). Over time
the immersion heater gasket may become stuck to the mating surface. To break the seal insert
a round bladed screwdriver into one of the pockets on the immersion heater and gently lever up
and down.
Carefully remove any scale from the surface of the element(s). DO NOT use a sharp implement
as damage to the element surface could be caused. Ensure sealing surfaces are clean and seals
are undamaged, if in doubt fit a new gasket.
Replace immersion heater(s) ensuring the lower (right angled) element hangs vertically downwards
towards the base of the unit. It may be helpful to support the immersion heater using a round bladed
screwdriver inserted into one of the thermostat pockets whilst the backnut is tightened. Replace
the thermostat(s) by carefully plugging the two male spade terminations on the underside of the
thermostat head into the corresponding terminations on the element.
Rewire the immersion heater(s) in accordance with Figure 9. Close and secure terminal
cover(s).
8.6 REFILLING SYSTEM
DO NOT switch on the immersion heater(s) or boiler until the system has been completely
refilled.
Close the drain tap. With the hot tap open, turn on mains water supply. When water flows from
the hot tap allow to flow for a short while to purge air and to flush through any disturbed par-
ticles. Close hot tap and then open successive hot taps in system to purge any air. The electrical
supply can now be switched on.
8.7 BENCHMARK
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