Abstract: An improved heating system air pressure sensing port. An example aircraft pitot tube heater uses Positive Temperature Coefficient (PTC) switching thermistors arranged to automatically sense the outside air temperature and heat to a design set point temperature. When a high outside air temperature is experienced, the pitot tube will not turn on. The pitot tube heater only turns on below the design set point and will consumes less current than the standard aircraft pitot tube heaters when operating at very cold temperatures. Virtually no current is drawn when the pitot tube increases past the set point, thus reducing the power drain on the aircraft system. The use of multiple thermistors gives the example pitot tube a level of failure redundancy that is not available in current pitot tube heaters.