Independent air conditioners and heat pumps - Tests and determination of performance characteristics

Last updated: 25 July 2020

SO 5151:2017 specifies performance testing, the standard conditions and the test methods for determining the capacity and efficiency ratings of air-cooled air conditioners and air-to-air heat pumps.


ISO 5151:2017 is applicable to the following equipment:

  • non-ducted air-cooled air conditioners and non-ducted air-to-air heat pumps; or
  • ducted air conditioners and/or ducted heat pumps rated at less than 8 kW and intended to operate at an external static pressure of less than 25 Pa.


ISO 5151:2017 is limited to:

  • residential, commercial and industrial single-package and split-system air conditioners and heat pumps;
  • factory-made, electrically driven and use mechanical compression;
  • utilizing single, multiple and variable capacity components;
  • multiple split-system utilizing one or more refrigeration systems, one outdoor unit and one or more indoor units, controlled by a single thermostat/controller.


The requirements of testing and rating contained in this document are based on the use of matched assemblies.


ISO 5151:2017 is not applicable to the rating and testing of the following:

a) water-source heat pumps or water cooled air conditioners;

b) multi-split-system air conditioners and air-to-air heat pumps (follow ISO 15042 for the testing of such equipment);

c) mobile (windowless) units having a condenser exhaust duct;

d) individual assemblies not constituting a complete refrigeration system;

e) equipment using the absorption refrigeration cycle;

f) ducted equipment except for those specified in this clause (follow ISO 13253 for the testing of such equipment).


ISO 5151:2017 does not cover the determination of seasonal efficiencies, which can be required in some countries because they provide a better indication of efficiency under actual operating conditions.

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