Check Electronic And Hydraulic System - Vaillant VCW 2O Instructions For Installation And Servicing

9.4 Sheet 4: Check Electronic and Hydraulic System
/ lsvoltage \
5 t o l 5 V D C a t D C
Check that Multiplug A
connections are clean,
tight and correctly
positioned.
ls Multiplug A
tested?
Check that wire is
connected to Terminal
l , l l o r l l l .
ReL to note 1 0
Pull otf connection
of NTC probe.
Ref. to note 7.
ls NTC probe
tested?
Replace faulty P.C.B.
with Main Switch.
Ref. to note 1.
z ls voltage '
t o l 5 V D C a t
Solenoid? Ref. to
ls Micro
Switch on
FFD tested?
Check grey connections
on FFD Micro Switch
lor 24OV AC from
Terminal 5 to
connections. Replace
Micro Switch if faulty.
Replace faulty
NTC probe.
Check black connections
on FFD Micro Switch
clean, tight and correctly
oositioned tor 5 to
15 V DC from brown
connection on DC
solenoid to black FFD
connections. Reolace
Micro Switch if faulty Ret.
to note 8.
Re{it connection
to NTC probe.
Has fuse on
Electronic
P . C . B .
Replace 0.25 Amp.
fuse.
Replace taulty
Electronic P.C.B.
Ref. to note 9.
Nole 6: The D.C.-voltage of 5-15 V is
controlled at the supply terminals
of the solenoid vatue. Attention!
When the indicator tums.to the
left, the measuring lines must be
reversed.
On ignition ot the bumer there
must be a D"C.-voltage ot 15 V.
The voltaqe decroases
according
io the flow
temperature until the electronic
(at approx. 5. V D.C.-voltage)
tums
oft the solenoid valve
(dead)
and the burner
extinguishes.
Thls test shows whether the
NTc-sensor has an inner shorl
circuit (resistance down at zero).
For this purpose, pull the NTC-
sensor
plug
off when the
appliance is cool
(Jlow
temperature less lhan 50'C).
lf the electronic is satisfactory,
the appliance must operate.
52
Note 7: