Weishaupt WTC 45-A, Installation And Operating Instructions Manual, Page: 54 / 90

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8 8 Safety and monitoring function
8.1 Temperature monitoring
Boiler circuit
The following functions are combined in the safety
temperature sensor of the boiler circuit:
• Safety temperature limiter
• Safety temperature monitor
Temperature aquisition for control and display is carried
out via the flow temperature sensor.
Safety temperature monitor STM (boiler)
If the programmed switch off temperature (95°C) is
exceeded the fuel supply is shut off and the fan and
pump run on is initiated (warning display W12).
An automatic restart of the system follows when the
temperature has been below the switch off point for a
minimum of one minute.
Safety temperature limiter STL (boiler)
If the programmed STL switch off temperature (105°C)
for the boiler circuit is exceeded the fuel supply is shut
off and the fan and pump run on is initiated (error
message F11).
Once the temperature has fallen below the switch off
temperature the permanent safety shut off can be reset
by pressing the reset key.
Flue gas system
The following functions for flue gas temperature
monitoring are combined in one sensor:
• Safety temperature limiter for flue gas
• Temperature measurment for display
Safety temperature limiter STL (flue gas)
If the programmed STL switch off temperature for the flue
gas circuit is exceeded the fuel supply is shut off and the
fan and pump run on is initiated (fault display F13).
To increase the availability of the boiler, the boiler rating is
reduced step by step when approaching the safety
temperature and a difference of 15K (105°C), to switch
to minimum rating at an approach of 10K (110°C). At a
difference of 5K (115°C) the boiler switches off (warning
message W16).
Differential temperature flow/flue gas system
The differential temperature monitoring limits the
range between flow and flue gas temperature
(warning message W15). if the warning appears 30
times consecutively the boiler goes to lockout with the
error
message F15.
Gradient monitoring boiler temperature
If the temperature gradient set is exceeded (system
parameter A9) the boiler is switched off.
This only occurs, if the boiler temperature is > 45°C
(warning message W14).