| Naics index | Naics index description |
|---|---|
| 221330 | Distribution of cooled air |
| 221330 | Distribution of heated air |
| 221330 | Distribution of steam heat |
| 221330 | Geothermal steam production |
| 221330 | Heat, steam, distribution |
| 221330 | Heated air distribution |
| 221330 | Heating steam (suppliers of heat) providers |
| 221330 | Steam heat distribution |
| 221330 | Steam heating systems (i.e., suppliers of heat) |
| 221330 | Steam supply systems, including geothermal |