- 15530 - Furnaces
- 15660 - Liquid Coolers and Evaporative Condensers
- 15670 - Refrigerant Condensing Units
- 15700 - Heating, Ventilating, Air Conditioning Equipment
- 15720 - Air Handling Units
- 15730 - Unitary Air Conditioning Equipment
- 15750 - Humidity Control Equipment
- 15760 - Terminal Heating and Cooling Units
- 15810 - Ducts
- 15820 - Duct Accessories
- 15850 - Air Outlets and Inlets
- 15860 - Air Cleaning Devices
- 23 31 00 - HVAC Ducts and Casings
- 23 31 13 - Metal Ducts
- 23 31 16 - Nonmetal Ducts
- 23 33 00 - Air Duct Accessories
- 23 33 46 - Flexible Ducts
- 23 35 13 - Sawdust Collection Systems
- 23 37 00 - Air Outlets and Inlets
- 23 37 13 - Diffusers, Registers, and Grilles
- 23 37 23 - HVAC Gravity Ventilators
- 23 40 00 - HVAC AIR CLEANING DEVICES
- 23 41 00 - Particulate Air Filtration
- 23 41 33 - High-Efficiency Particulate Filtration
- 23 41 43 - Ultra-Low Penetration Filtration
- 23 43 00 - Electronic Air Cleaners
- 23 50 00 - CENTRAL HEATING EQUIPMENT
- 23 54 00 - Furnaces
- 23 54 13 - Electric-Resistance Furnaces
- 23 54 16 - Fuel-Fired Furnaces
- 23 60 00 - CENTRAL COOLING EQUIPMENT
- 23 63 00 - Refrigerant Condensers
- 23 65 33 - Liquid Coolers
- 23 70 00 - CENTRAL HVAC 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 76 00 - Evaporative Air-Cooling Equipment
- 23 80 00 - DECENTRALIZED HVAC EQUIPMENT
- 23 81 00 - Decentralized Unitary HVAC Equipment
- 23 81 13 - Packaged Terminal Air-Conditioners
- 23 81 16 - Room Air-Conditioners
- 23 81 26 - Split-System Air-Conditioners
- 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
- 23 84 00 - Humidity Control Equipment
- 23 84 13 - Humidifiers
- 23 84 16 - Dehumidifiers
- 23 84 19 - Indoor Pool and Ice-Rink Dehumidification Units
- 44 11 16 - Industrial Dust Collectors