This Propex Omron air flow sensor is responsible for monitoring the volume of air moving through the combustion chamber of the Propex HS-series heaters.  This measurement is essential for proper combustion and, if the air flow is out of specification, the heater will throw a fault code (usually four-flash) in order to maintain user safety.

If you have a four-flash fault code on your Propex heater, please read through this four-flash fault code article to help diagnose the issue.  

This sensor is found in heater models manufactured from April 2015.