Heatrae Sadia Megaflo solar Installation Manua page 28

9.5 DESCALING IMMERSION HEATER(S)
Isolate the electrical supply before removing covers and drain unit of water. 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. Unscrew immersion heater
backnut(s) and remove immersion heater from the unit. A key spanner is supplied with the Megaflo
Solar 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 Diagram 10. Close and secure terminal
cover(s).
9.6 EXPANSION VESSEL CHARGE PRESSURE
Remove the dust cap from the top of the expansion vessel. Check the charge pressure using
a tyre pressure gauge. The charge pressure (with the system de-pressurised) should be 0.3
MPa (3 bar). If it is lower than the required setting it should be re-charged using a tyre pump
(Schrader valve type). DO NOT OVER CHARGE. Re-check the pressure and when correct
replace the dust cap.
9.7 REFILLING SYSTEM
DO NOT SWITCH ON THE IMMERSION HEATER(S) OR BOILER UNTIL THE SYSTEM HAS
BEEN COMPLETELY REFILLED.
Close the drain tap. With 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 particles.
Close hot tap and then open successive hot taps in system to purge any air. The electrical sup-
ply can now be switched on.
9.8 BENCHMARK
On completion of any maintenance or service of the Megaflo Solar the Benchmark
lation, Commissioning and Service Record Log Book" should be filled in to record the actions
taken and the date the work was undertaken.
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LOG BOOK
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