Magnesium Anode; Descaling Information - andrews RSC 9/145 Service Manual

6.4

Magnesium Anode

6.5

Descaling Information

Issue 4 21042018
A magnesium sacrificial anode is fitted in the water storage
vessel. The function of the anode is to provide additional
protection, against corrosion, for the inside of the vessel. The
condition of the anode should be checked regularly and
replaced. In order to remove the anode close the cold water
feed stop valve, open a hot water tap and, by opening the water
heater drain valve, drain off sufficient water to clear the top of
the vessel. The anode/outlet nipple can then be unscrewed from
the top of the heater.
The original diameter of the anode is 22mm. If, at any point
along its length, the anode is eroded to half, or less, of the
original diameter is should be replaced with new. Particular
attention should be paid to the extreme ends.
If the anode is encrusted with limescale it should be either
cleaned or replaced.
Where Correx Anodes are fitted no Anode maintenance is
required.
When descaling the storage water heater your attention is drawn
to the following guidelines.
Caution
Due to the corrosive nature of descaling fluid, it is
essential that suitable protective clothing is used and
adequate ventilation available when descaling.
It is important to follow descaling manufactures
instructions before and during use.
1. Turn gas control on water heater to 'OFF position and isolate
the gas supply.
2. Close water inlet valve and drain heater tank.
3. Remove magnesium sacrificial anode if fitted.
Note
It is recommended that a new anode is fitted.
4. Add suitable hydrochloric based descale acid, the
requirement is normally 5 litres for dependent on the amount
of limescale present.
5. After a minimum of one hour restore gas supply and turn on
main gas burner for 2 minutes.
6. Isolate gas supply and drain off descale fluid through drain
port.
7. Open cold water feed valve and fill heater tank.
8. Drain and flush out heater for minimum of 30 minutes.
9. Replace anode.
10. Restore gas supply and re-light heater.
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