Installation and operating instruction
Gas condensing unit WTC-GB 15-B Compact and WTC-GB 25-B Compact
3 Product description
83309302 1/2018-05 La
14-196
3.3.3 Safety and monitoring functions
3.3.3.1 Flow sensor eSTB / flue gas sensor
Flow sensor eSTB
The fuel supply is shut off and the pump run-on is activated if the temperature ex-
ceeds 95 °C (
W 12
). The appliance restarts automatically if the temperature drops
below the target supply value for 1 minute.
If the temperature exceeds 105 °C, the fuel supply is shut off and the pump run-on
is activated. The system goes to lockout (
F 11
).
Flow temperature increase eSTB (gradient)
If the flow temperature increases too fast, the appliance is switched off (
W 14
). If
the warning occurs several times in succession, the system goes to lockout
(
F 14
). This function is only activated at a temperature of > 45 °C.
Differential temperature flow eSTB / flue gas
The appliance is switched off if the difference between the flow temperature and
the flue gas temperature exceeds a preset value (
W 15
). If the warning occurs sev-
eral times in succession, the system goes to lockout (
F 15
). When approaching
this value, first the pump capacity is increased and then the burner capacity is re-
duced.
Flue gas sensor
If the flue gas temperature exceeds 120 °C (factory setting), the fuel supply is shut
off and the pump run-on is activated (
F 13
). On proximity to the safety temperature
the burner capacity will be reduced, at a difference of 5 K (115 °C) the burner
shuts down (
W 16