Fault Finding - Vaillant Vantage 120 Installation Instructions Manual

11 Fault finding

11 Fault finding
Note:
Only genuine spare parts supplied
by Vaillant Limited must be used.
Fault A:
The water from the cylinder is cold.
Does boiler operate?
Is 3-port valve in
corect position? (Mid
or DHW position).
Vent heating coil of
air (H, fig. 4).
Fig. 16
32
Do external controls
NO
function?
YES
Does cylinder
NO
thermostat operate?
YES
Is operation now
NO
OK?
Fault remedied.
Remedy fault
YES
according to boiler
instructions.
NO
Remedy fault
according to controls
instructions.
Replace cylinder
NO
thermostat.
YES
Check/replace
3-port valve.
YES
Vaillant Vantage 120/150/200