ANSI Z21.40.4-1996/CGA 2.94-M96 (R2012)

SCOPE This standard establishes methods of testing and rating gas-fired, heat pumps for space-conditioning performance. The procedures apply to factory-made, space-conditioning, unitary heat pumps which utilize gas as the primary fuel. This includes engine-driven heat pumps, absorption-cycle heat pumps, desiccant-type heat pumps, and other gas-fired heat pumps. The heat source/sink for the heat pumps may be outdoor air, ground water, or closed-loop water. The heat pumps 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 may include other functions. Appropriate portions of this standard can be applied to heat pumps which have a gas input that varies so that the output matches the cooling or heating load, to heat pumps which have a single level gas input which varies as a function of ambient conditions, and to heat pumps which have a constant gas input regardless of load or ambient conditions, and to heat pumps with several discrete levels of gas input. In addition to applying to heat pumps which provide year-round space conditioning, portions of this standard can be applied to heat pumps which provide space cooling only or space heating only. Also, procedures are provided for testing and rating water-cooled air conditioners and water-cooled chillers which reject condenser heat with a cooling tower, air- and water-cooled condensing units, and desiccant ventilation-air dehumidifiers.