SERVICING
SECTION 6
MAGNESIUM
ANODE
DESCALING
INFORMATION
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 (
7
⁄
8
”). 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.
SAFETY FIRST - DUE TO THE CORROSIVE NATURE OF THE DESCALE FLUID IT IS
ESSENTIAL THAT SUITABLE PROTECTIVE CLOTHING EQUIPMENT IS USED AND
ADEQUATE VENTILATION IS 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.
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 (MAXIMUM).
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.
21
