Standard 610 Scope
This standard establishes a single set of requirements for the testing and rating of humidification capacity, air pressure drop, and energy consumption and energy efficiency (where used) for central system humidifiers used in residential applications. Central system humidifiers are defined as humidifiers intended to be installed on ducted residential heating/cooling central systems.

Standard 620 Scope
This standard establishes a single set of requirements for the testing and rating of humidification capacity, power input, and energy input of supplementary heat (where used) for self-contained humidifiers for residential applications. Self-contained humidifiers are defined as humidifiers intended to be installed with a water make-up line and/or drain and electrical services — it may or may not be installed within the humidified space.

Standard 640 Scope
This standard establishes a single set of requirements for the testing and rating of humidification capacity, power input, and energy input of supplementary heat (where used) for humidifiers used in commercial and industrial applications. Devices of the following types are included: atomizing, electric resistance steam generators, electrode steam generators, heat exchangers, infrared, steam injection, and wetted media.