This class is offered in the Hyflex format, meaning the work can be accomplished online with the opportunity to attend weekly classes either in person or via Zoom. HVAC Apprentice Year 3: Course D; This is one of four 8-week courses that comprise the Year 3 HVAC Apprentice training. Year 3 of the HVAC Apprentice training covers basic HVAC Controls, 39 hours, Basic Airflow & Duct Sizing, 30 hours, Air Conditioning & Refrigeration System Operation & Components, 33 hours, Intro to Hydronic, 9 hours, Basic Sheet Metal Layout, 33 hours, & Intro to Service, 12 hours.