2.8 Safety devices
3 MAIN SWITCH
(switches off the power supply)
Before carrying out work on the boiler:
❒ Tap “Boiler off”
➥ Automatic mode is switched off
➥ Control system follows the boiler shutdown procedure
❒ Switch off the main switch and let the boiler cool down
4.5 BOILER OFF
(switches off the boiler to prevent overheating)
❒ Tap “Boiler off”
➥ Automatic mode is switched off
➥ Control system follows the boiler shutdown procedure
➥ The pumps continue to run
NOTICE! Never use the main switch!
8 HIGH-LIMIT THERMOSTAT (STL)
(protection against overheating)
The STL switches off the combustion system when the boiler reaches 105°C. The
pumps continue to run. Once the temperature falls below approx. 75°C, the STL can
be reset mechanically.
TV THERMAL DISCHARGE VALVE
(protection against overheating)
The thermal discharge valve opens at approx. 100°C and feeds cold water to the
safety heat exchanger to lower the boiler temperature
SV SAFETY VALVE
(protection against overheating/excess pressure - supplied by the
customer)
When the boiler pressure reaches a maximum of 3 bar, the safety valve opens and the
heated water is blown off in the form of steam.
Safety
2
Safety devices
Operating Instructions TX 200-250 | B1060217_en 19