This air flow sensor update kit allows heaters manufactured prior to 2010 to use a more modern air flow sensor.
Heaters built before 2010 used a spinning wheel optical sensor which could foul when exposed to harsh conditions. This update kit contains a new MEMS D6F air mass sensor which functions with no moving parts.
This kit fits the HS1600, HS1800, and pre-2/2010 HS2000 and HS2800.