This is the second level of training in the NCCER HVAC craft. Modules include: Commercial Airside Systems; Chimneys; Vents and Flues; Introduction to Hydronic Systems; Air Quality Equipment; Leak Detection, Evacuation, Recovery, and Charging; Alternating Current; Basic Electronics; Introduction to Control Circuit Troubleshooting; Troubleshooting Gas Heating; Troubleshooting Cooling; Heat Pumps; Basic Installation and Maintenance Practices; Sheet Metal Duct Systems; and Fiberglass and Flexible Duct Systems. Prerequisite: HVAC Level 1.