Installation and operating instruction
Oil condensing boiler WTC-OB 18-B
10 Troubleshooting
83311002 1/2018-03 La
94-132
10.3 Warning codes
The following faults must only be rectified by qualified personnel:
Warning codes Cause
Rectification
W12
Temperature at flow sensor > 95 °C
(system goes to lockout after 12warnings with
F12
)
Check the water flow
Check function of the pumps
Vent unit on the water side
W15
Temperature differential between flow and return
to high
(system goes to lockout after 30 warnings with
F15
)
Check function of pump, if necessary increase
pump capacity
Ensure system circulation
W16
Flue gas temperature too high (parameter
33
- 5 K)
(system goes to lockout after 10 warnings with
F16
)
Wait for cooling (10 minutes)
Check heat cell
W17
Combustion air temperature too high
(after repeated warnings system goes to lockout
with
F17
)
Wait for cooling (10 minutes)
Check the heat insulation
Check combustion air sensor, replace if ne-
cessary
Flow sensor and combustion air sensor mixed
up, check electrical connections
W19
Combustion chamber pressure too high
(system goes to lockout after 3 warnings with
F19
)
Check heat cell, if necessary clean [ch. 9.5]
Check flue gas system
Check the condensate drain
Check combustion chamber pressure sensor,
if necessary replace
Check combustion for pulsation, if necessary
increase mixing pressure
W22
Flame failure during operation
(system goes to lockout after 5 warnings with
F22
)
Check oil nozzle, if necessary replace
[ch. 9.10]
Check oil supply
Check oil pump, if necessary replace
[ch. 9.14]
Check flame sensor (USB-readout unit
KLC Com, Order No.: 90012181), if neces-
sary replace
Clean the light tube end piece, if necessary
check burner setting.
Check soundness of flue gas system [ch. 7.3].
Check the condensate drain
Check burner setting
Set nozzle distance [ch. 9.6]
Check mixing head [ch. 9.7]
W24
Input H2 is closed, parameter
17
on
3
(burner
lockout function)
Check components connected to input H2
[ch. 6.10]
W25
Alarm condensate lift pump
Check condensate lift pump
Level switch has been triggered
Check termination well, if necessary clean or
drain
Check level switch
W27
Combustion chamber pressure sensor defective
Check sensor and cable, if necessary replace
W28
System pressure sensor/return flow sensor de-
fective
Check sensor and cable, if necessary replace
(drain appliance prior to replacing)
W33
External sensor defective
Check the sensor and cable and replace if ne-
cessary
W34
DHW sensor (B3) defective
Check the sensor and cable and replace if ne-
cessary
