AHRI 420 (I-P) and 421 (SI): Performance Rating of Forced-Circulation Free-Delivery Unit Coolers for Refrigeration

Standard Scope

This standard applies to factory-made, forced-circulation free-delivery unit coolers, as defined in Section 3, operating with a volatile refrigerant fed by either direct expansion or liquid overfeed at wet or dry conditions, or both.


This standard does not apply to:

  1. Air-conditioning units used primarily for comfort cooling where testing methods are given in other standards

  2. Unit coolers operating at latent load conditions with refrigerant saturation temperature < 32°F to prevent frost

  3. Unit coolers installed in or connected to ductwork

  4. Unit coolers using zeotropic refrigerants with glides greater than 2.0°F

  5. Field testing of unit coolers

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