Air duct airflow sensor with internal low-pressure detector

An airflow sensor assembly for an air duct, the air duct having an interior wall and an exterior wall;

• comprising:
• a first pressure structure;
• a second pressure structure, comprising:
• an airflow restriction surface;
• and
• a plurality of first apertures defined at the airflow restriction surface and spaced around a periphery of the air duct;
• a first gasket having a first connecting opening, the first gasket being fitted over the exterior wall and proximate the first apertures and the first gasket and the airflow restriction surface being configured to define a chamber;
• and
• either (a) at least one pressure sensor configured to be fluidly coupled to both the first pressure structure and the second pressure structure or (b) a first pressure sensor configured to be fluidly coupled to the first pressure structure and a second pressure sensor configured to be fluidly coupled to the second pressure structure.

A method of sensing airflow in an air duct, the method comprising:

• receiving a first air pressure measurement from a first pressure detection structure;
• receiving a second air pressure measurement from a second pressure detection structure, the second pressure detection structure comprising:
• a restrictive portion disposed within an interior wall of the air duct, the restrictive portion having first apertures defined therein;
• and
• a first tube fluidly coupled to a first connecting opening in communication with a chamber at least partially defined by the restrictive portion;
• and
• calculating an air velocity through the air duct based on the first air pressure measurement and the second air pressure measurement.