Minimal or maximal thermostat for monitoring supply air and controlling fans in ventilation and air conditioning systems. Type-tested by TÜV according to DIN EN 14597. For warm air heaters according to DIN 4794. Sensor failure: In the event of sensor damage or failure, contacts 1 and 4 of the fan open. Intrinsic safety/cold protection: The devices are intrinsically safe, meaning that in the event of loss of the sensing medium, such as due to sensor failure, the burner is shut down. Since negative temperatures can cause the same effect through volume reduction of the sensing medium, the devices are adjusted via the cold screw to ensure that the burner only shuts down at temperatures below 15 °C. Re-enabling can only be done manually at temperatures above approximately 5 °C using the manual reset button. Overheating protection: The device protects against uncontrolled overheating, caused for example by heat accumulation or gradual loss of capillary fill due to undetectable damage to the sensor or capillary tube. When a temperature of 220 °C is reached, the safety solder in the sensor melts, and the device shuts down the burner for safety due to loss of the fill medium. The burner cannot be restarted. The device then becomes unusable and serves as proof of the existing overtemperature of at least 220 °C.