Fault finding
1) Pressure and temperature valve dripping/running all the time.
Cause: Thermal cut-out and thermostat have failed (this is only the case if the
water being discharged is near to boiling).
Mains pressure is too high. A pressure reducing valve must be fitted (see fig. 3).
2) Pressure relief valve dripping/running all the time.
Cause: Mains pressure is above 3.5 bar. A pressure reducing valve must be fitted
(see fig. 2).
3) Dripping while unit heating.
Cause: Not enough pipe work for expansion; or stop-cock, non-return valve or
pressure reducing valve has been fitted on the cold mains supply (see fig. 2). If an
expansion vessel has been fitted, the charge may have failed.
4) No hot water.
Cause: Thermal cut-out has operated.
The heating element has burnt-out.
The thermostat is faulty.
5) Milky water.
Cause: This is a result of heavily limed and oxygenated water being heated. This
is harmless and the cause is the water or a loose jumper washer in the outlet
tap and not the heater itself.
6) No water at all.
Cause: Valve incorrectly fitted.
Debris in the mains.
Mains water supply turned off.
7) Grey metallic deposit in the water
Cause:Corrosion of the sacrificial anode.
(Note: Corrosion of the sacrificial anode is normal operation of the unit)
8) Rapid depletion of the sacrifical anode (see 7)
Cause: Di-electric junctions not fitted
Water softener fitted on incoming supply to water heater
(Softened will cause the anode to deplete more rapidly than hard water)
Note Whilst Ariston do not advise against the use of water softener devices, the
end user must be advised that rapid depletion of the sacrificial anode may
occur as a result of the softened water which can result in metallic grey deposit
in the water.
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