Take a DEEP breath. The Boiler tube and the FLUE tube in this discussion is the SAME. This is from the ARP install. "The ARP temperature sensor is clipped onto the boiler tube. The boiler tube is easy to identify because the electric heating elements are attached directly to the boiler tube". The Norcold recall IS attached to the Flue/Boiler tube but at a lower area by the Heat elements. The ARP device is mounted about 6 inches above the Norcold sensor. But BOTH mount on the same tube. Norcold DOES have a out of level/overheat built in system. It is NOT as good or precise as the ARP system. Norcolds is called the NO CO system and will shut the refer down when cooling unit protocols are out of normal safe parameters. The ARP system reacts much quicker and more precise. Which makes it a better sensor system. Doug