SIEMENS 544-342-24 Flexible HVAC Averaging Duct Temperature Sensor. Buy It now 75 gets free shipping to the lower 48 states. SIEMENS 544-342-24 Flexible HVAC Averaging Duct Temperature Sensor list these parts to the best of our knowledge, please make sure you know when you're buying. It is the buyer's responsibility to make sure this item will work for his or her needs.