11 Fault finding
Vaillant Vantage 120/150/200
34
Fig. 18
Water discharging from temperature/
pressure relief valve (TPRV).
Manually reset the TPRV. Is
discharge still occuring?
YES
NO
Is discharge occuring only
when the boiler is in use?
Is discharge occuring only
when the immersion heater
is in use?
Are immersion heater
thermostat and cut out
faulty?
YES
Replace TPRV.
Replace immersion heater.
NO
YES
NO
Is operation now OK?
OK
Fault remedied.
NOT OK
Check temperature control
of boiler.
Does 3-port valve change to
heating position when
cylinder reaches
temperature?
Check operation of
cylinder thermostat.
YES
OK
NO
Remedy fault
according to boiler
instructions.
NOT
OK
Replace cylinder
thermostat.
NOT
OK
Check operation of
3-port valve.
Replace
3-port valve.
NOT
OK
OK
Is discharge still occuring?
OK
NO
YES
NO
Replace TRPV.
YES
VIH_F
ault_C
Fault C:
