Methods and systems to measure a volumetric fluid flow rate through a fluid flow passage, such as an air handler of a HVAC system, are described. A width W1 close to one end portion of the center leg in a Y-axis direction perpendicular to a facing direction of the outer legs is smaller than a width W2 close to the other end portion. The read data information includes read data symbols, where the average duration of the read data symbols, measured at the interface, defines a symbol time interval. A module controller of a temperature control system is configured to verify the unique identification number of the thermocouple assembly prior to allowing data to be transferred between the temperature measuring device and a temperature controller. In particular, by selecting a wedge-shaped inner profile, the design and fabrication of the junction can be simplified. The panels, once locked together, have little movement along their x, y or z axis.