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. Suitable for warm air heaters according to DIN 4794. Sensor failure: In case of sensor damage or failure, contacts 1 and 4 of the fan will 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 will be shut down. Since negative temperatures can cause the same effect due to volume reduction of the sensing medium, the devices are adjusted using the cold screw to ensure that they only shut down the burner at temperatures below 15 °C. The reactivation 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 filling due to invisible 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 filling medium. The burner cannot be reactivated. The device then becomes unusable and serves as evidence of the existing overtemperature of at least 220 °C. Overheating protection thermostat for electric heating registers and directly fired air heaters in oil and gas operation.