Draft Details

Designation:Z21.40.4/CSA 2.94
Source:CSA
Contact name:[email protected]
Review start date:Dec 1, 2022
Review end date:Jan 30, 2023
Categories:Energy
Contact email:kelly.yaremko(at)csagroup.org
Draft Scope/Description:

1.1 Inclusion

This Standard establishes methods of testing and rating for constant volume and/or variable refrigerant flow 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/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.

Rationale: Explicitly inclusive of variable refrigerant flow-type gas-fired heat pumps. Further changes are clarifications, not a change in scope.

The heat pump may include other functions. Appropriate portions of this Standard may 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 may be applied to heat pumps which provide space cooling only or space heating only. 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. 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.

Rationale: Clarification, not a change in scope.

Clause 2 lists the references used in developing the Standard.

Clause 3 lists definitions of terms used in this Standard.

Clause 4 lists the thermal testing that is required for each class of appliance. The type of test and the levels of gas input are prescribed. For air-source/sink appliances, the outdoor temperature conditions are specified, and for water-source/sink appliances, the entering source/sink water temperatures are specified.

Clause 5 identifies additional conditions at which the thermal tests specified in Clause 4 are to be conducted. This includes the voltage of auxiliary electric input, indoor air quantities, return air temperatures, water flow rates, and return water temperatures.

Clause 6 outlines the procedures to be followed when thermal testing. This includes steady-state tests and cyclic tests for the cooling mode, and steady-state tests, cyclic tests, and frost accumulation tests for the heating mode.

Clause 7 covers calculation procedures for determining steady-state capacity and input ratings for the appliance operating in the cooling mode. Appropriate adjustments are made to the input and output values determined by the tests to normalize the impacts of auxiliary electric inputs.

Clause 8 covers calculation procedures for determining steady-state capacity and input ratings for the appliance operating in the heating mode. Appropriate adjustments are made to the input and output values determined by the tests to normalize the impacts of auxiliary electric inputs. The next four sections of the standard cover calculation procedures for determining seasonal and annual performance parameters for residential and commercial applications.

Clause 9 covers calculation procedures for determining cooling-mode seasonal output and energy consumption ratings for appliances suitable for installation in residential applications. The steady-state cooling ratings from Clause 7 are required as inputs for these determinations. A sample calculation is provided in Annex A.

Clause 10 covers calculation procedures for determining heating-mode seasonal output and energy consumption ratings for appliances suitable for installation in residential applications. The steady-state heating ratings from Clause 8 are required as inputs for these determinations. A sample calculation is provided in Annex B.

Clause 11 covers calculation procedures for determining annual energy consumption for appliances suitable for installation in residential applications. The seasonal energy consumption data determined in Clauses 9 and 10 are required as inputs for these calculations.

Clause 12 covers calculation procedures for determining cooling-mode average hourly output and energy consumption ratings for appliances suitable for installation in commercial applications. The steady-state cooling ratings from Clause 7 are required as inputs for these determinations. A sample calculation is provided in Annex C.

Clause 13 covers procedures for determining outdoor sound power level ratings for air-source appliances.

Annex A: An informative sample calculation of cooling seasonal performance parameters for residential air-source appliances

Annex B: An informative sample calculation of heating seasonal performance parameters for residential air-source appliances

Annex C:  Covers an informative sample calculation of cooling integrated part load value parameters for commercial appliances

Annex D: Informative list of Harmonized Appliances

Annex E: Informative methods of determining efficiency ratings and operating costs of gas-fired, heat pumps for space-conditioning performance

Annex F: Informative bibliography

1.2 Units of Measure

The values given in SI units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.

1.3 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 (nonmandatory) to define their application.

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