Installation and operating instruction
Gas condensing unit WTC-GB 15-B Compact and WTC-GB 25-B Compact
10 Troubleshooting
83309302 1/2018-05 La
134-196
The following warnings must only be rectified by qualified personnel:
Warning
Cause
Rectification
W 25
Flame failure during stabilisation
time
If occurring occasionally:
(e. g. due to strong wind at the flue gas system):
Requires no action.
If occurring frequently:
Check gas connection pressure [ch. 7.1.2]
(flow operated safety device).
Check the ionisation electrode, replace if
necessary [ch. 9.1.4].
Clean burner surface, if necessary replace
[ch. 9.1.3].
Check combustion air for contamination.
With room-air-independent operation, check
soundness of flue gas system [ch. 7.3].
Flue gas resistance too high, check condens-
ate drain.
Check flue gas shut off device, if necessary
replace.
W 27
Gas pressure too low
After 5 burner shutdowns in a row, the system is
locked for approx. 15 minutes.
Note: Only in conjunction with inbuilt gas pressure
switch (accessory).
Check gas connection pressure [ch. 7.1.2]
(flow operated safety device).
W 36
Check system pressure, if necessary top up
For roof heating centres, reduce parameter
2.2.7 Minimum system pressure
warning
if necessary.
W 40
Internal pump signals warning
Check circulation pump, replace if necessary.
W 42
Internal pump return signal incorrect
Check plug cable PWM circulation pump.
Check circulation pump.
W 43
Fan speed outside of range
Check the fan and cable, replace if necessary.
W 48
Air in system
Purge system (heating circuit and DHW cir-
cuit).
Purge unit on the water side, initiate program
Automatic purging
Increase system pressure.
Install the deaerator on site.
W 61
Ionisation signal outside of toler-
ance limits
Check the ionisation electrode, replace if
necessary [ch. 9.1.4].
Check setting of
type of gas
.
W 62
Control signal of gas correcting ele-
ment or fan outside of tolerance lim-
its
Check the ionisation electrode, replace if
necessary [ch. 9.1.4].
With room-air-independent operation, check
soundness of flue gas system [ch. 7.3].
Flue gas resistance too high, check condens-
ate drain.
Check gas connection pressure [ch. 7.1.2]
Check setting of
type of gas
[ch. 6.6.9.6].
Check fan, replace if necessary
W 63
SCOT system error
Carry out calibration via output measurement
[ch. 6.6.7.3].
W 66
Calibration unsuccessful
Carry out calibration via output measurement
[ch. 6.6.7.3].