Minimum or maximum thermostat for supply air monitoring and fan control in ventilation and air conditioning systems. Type-tested by TÜV according to DIN EN 14597. For warm air heaters according to DIN 4794. Sensor break: In case of sensor damage or sensor break, contacts 1 and 4 of the fan open. Intrinsic safety/cold protection: The units are intrinsically safe, i.e. if the sensor medium is lost, e.g. due to sensor breakage, the burner is switched off. Since minus temperatures produce the same effect by reducing the volume of the sensor medium, the units are adjusted by means of the "cold screw" in such a way that they only switch off the burner at temperatures below -15 °C. The units can only be switched on again manually at temperatures below -15 °C. The burner is then switched off again. The unit can only be switched back on manually at temperatures higher than approx. - 5 °C using the manual reset button. Overheating protection: The unit protects against uncontrolled overheating, caused e.g. by heat accumulation or by creeping capillary filling loss in the case of invisible damage to the sensor or capillary tube, etc. When a temperature of 220°C is reached, the safety slot in the sensor melts and the unit switches off the burner to the safe side due to loss of filling medium. The burner cannot be switched on again. The unit is then unusable and serves as proof of the existing excess temperature of at least 220°C.