- 15500 - Heat Generation
- 15530 - Furnaces
- 15540 - Fuel-Fired Heaters
- 15670 - Refrigerant Condensing Units
- 15700 - Heating, Ventilating, Air Conditioning Equipment
- 15710 - Heat Exchangers
- 15720 - Air Handling Units
- 15760 - Terminal Heating and Cooling Units
- 15780 - Energy Recovery Equipment
- 15800 - Air Distribution
- 15830 - Fans
- 15840 - Air Terminal Units
- 23 30 00 - HVAC AIR DISTRIBUTION
- 23 34 00 - HVAC Fans
- 23 34 13 - Axial HVAC Fans
- 23 34 16 - Centrifugal HVAC Fans
- 23 34 23 - HVAC Power Ventilators
- 23 34 33 - Air Curtains
- 23 36 00 - Air Terminal Units
- 23 36 13 - Constant-Air-Volume Units
- 23 36 16 - Variable-Air-Volume Units
- 23 50 00 - CENTRAL HEATING EQUIPMENT
- 23 54 00 - Furnaces
- 23 54 13 - Electric-Resistance Furnaces
- 23 54 16 - Fuel-Fired Furnaces
- 23 55 00 - Fuel-Fired Heaters
- 23 55 13 - Fuel-Fired Duct Heaters
- 23 55 23 - Gas-Fired Radiant Heaters
- 23 55 33 - Fuel-Fired Unit Heaters
- 23 57 00 - Heat Exchangers for HVAC
- 23 57 16 - Steam-to-Water Heat Exchangers
- 23 57 19 - Liquid-to-Liquid Heat Exchangers
- 23 60 00 - CENTRAL COOLING EQUIPMENT
- 23 63 00 - Refrigerant Condensers
- 23 70 00 - CENTRAL HVAC EQUIPMENT
- 23 71 00 - Thermal Storage
- 23 72 00 - Air-to-Air Energy Recovery Equipment
- 23 72 13 - Heat-Wheel Air-to-Air Energy-Recovery Equipment
- 23 72 16 - Heat-Pipe Air-to-Air Energy-Recovery Equipment
- 23 73 13 - Modular Indoor Central-Station Air-Handling Units
- 23 73 23 - Custom Indoor Central-Station Air-Handling Units
- 23 74 00 - Packaged Outdoor HVAC Equipment
- 23 75 00 - Custom-Packaged Outdoor HVAC Equipment
- 23 80 00 - DECENTRALIZED HVAC EQUIPMENT
- 23 82 00 - Convection Heating and Cooling Units
- 23 82 16 - Air Coils
- 23 82 19 - Fan Coil Units
- 23 82 23 - Unit Ventilators
- 23 82 26 - Induction Units
- 23 82 33 - Convectors
- 23 82 36 - Finned-Tube Radiation Heaters
- 23 82 39 - Unit Heaters
- 44 11 00 - Air Pollution Control Equipment