CSA/ANSI Z21.40.4:23 • CSA 2.94:23

1 Scope 1.1 Inclusions This Standard establishes methods of testing and rating for constant volume and/or variable refrigerant flow gas-fired, heat pumps for space-conditioning performance. These methods apply to factory-made, space-conditioning, unitary heat pumps that use gasoline as the primary fuel. This Standard applies to engine-driven heat pumps, absorption-cycle heat pumps, desiccant-type heat pumps, and other gas-fired heat pumps. The heat source/sink for these heat pumps may be outdoor air, ground water, or closed-loop water/brine. The heat pumps may provide the functions of year-round space conditioning either by direct heating and cooling of air or indirectly by the production of heated and chilled water. The heat pump can include other functions. Portions of this Standard may be applied to a) heat pumps with a gas input that varies so that the output matches the cooling or heating load; b) heat pumps with a single level gas input that varies as a function of ambient conditions; c) heat pumps that have a constant gas input regardless of load or ambient conditions; and d) heat pumps with several discrete levels of gas input. In addition to applying to heat pumps that provide year-round space conditioning, portions of this Standard may be applied to heat pumps that provide only space cooling or space heating. Procedures are also provided for testing and rating water-cooled air conditioners and water-cooled chillers that reject condenser heat with a cooling tower, air and water-cooled condensing units, and desiccant ventilation-air dehumidifiers. Note: Service hot water output from heat pumps, solely or in addition to space conditioning, is covered under ANSI/ASHRAE 118.1 and ANSI/ASHRAE 118.2. 1.2 Terminology In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application. 1.3 Units of measure The values given in U.S. customary units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.