Air conditioners fall into three broad categories single unit systems, packaged air conditioners (PACs) and larger commercial and industrial cooling towers. Single unit systems are purchased and used in small commercial buildings and dwellings.

Packaged air-conditioners (PACs) the main focus of this regulatory statement provide heating, cooling and air-conditioning residential (HVAC) in small to medium commercial and institutional buildings, and in larger residential dwellings. Larger air cooling towers are used in medium to larger commercial and industrial buildings.