... damage for over temperature Some appliances. wax melting heater,vapor generator,humidifier,water boiler,liquid warmer,coffee warmer ... ,hand/foot warmer,massager,physical therapy heater. 1) Aluminum shell. PTC heater is very appropriate under 260 temperature. ... Main appliances: hair straightener, hair crimper, wax melting heater, humidifier, water boiler, liquid warmer, coffee warmer, polymer ...