CSA/ANSI Z21.47:26/CSA 2.3:26

N/A
Preface This is the ninth edition of CSA/ANSI Z21.47/CSA 2.3, Gas-fired central furnaces . It supersedes the previous editions published in 2021, 2016, 2012, 2006, 2003, 2001, 1998, and 1993. The following are the major changes to this edition: a) manufactured gas and mixed gas types have been removed; b) Clause 4.6.13 has been added to address specific installation conditions; c) the requirements in Clause 4.10.1 have been updated to reflect revisions to ANSI Z21.20, particularly those regarding ignition control system standards; d) the test method in Clause 4.14.14.2 has been revised to accommodate changes in non-metallic venting standards; e) Clause 4.23.2 has been revised to clarify instructions related to the installation manual requirements; f) Clause 4.25 has been updated to address additional safety and performance requirements; g) a formula has been added to Clause 5.8.1.2 to assist in determining the correct procedure for computing air-free CO; h) the minimum temperature requirement has been removed from Clause 5.17; i) Clauses 5.36.6 and 7.4.5 have been removed from the Standard; j) Clause 13.1 has been removed; k) Table 10 has been updated to align with the latest gas composition standards; l) Table 11 has been revised for consistency with current industry practices; m) the test device and average free-stream pressure values in Figure 17 have been updated; and n) Annex S has been added to provide a standardized formula for furnace input calculations. This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard. This Standard was prepared by the Z21/CSA Subcommittee on Standards for Gas-Fired Central Furnaces, under the jurisdiction of the Technical Committee on Bi-National Gas Appliances and Related Accessories and the Strategic Steering Committee on Fuels and Appliances, and has been formally approved by the Technical Committee. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. This Standard has been approved by the American National Standards Institute (ANSI) as an American National Standard. Scope 1.1 Inclusions This Standard applies to automatically operating gas-fired central furnaces, referred to as "furnaces" in this Standard, for installation in residential, commercial, and industrial structures, including furnaces for direct vent, recreational vehicle, outdoor, and manufactured (mobile) homes. These furnaces can include a cooling unit. This Standard assumes all units are constructed entirely of new and unused parts and materials. 1.2 Appliance categories This Standard applies to Category I, Category II, Category III, and Category IV central furnaces. 1.3 Application and operation of furnaces This Standard applies to furnaces of the types defined in Clause 3 that are designed to supply heated air through ducts to spaces remote from or adjacent to the furnace location. Location and use of such furnaces with respect to the spaces being heated necessitates automatic operation of the appliance. 1.4 Thermal efficiency of furnaces This Standard covers the thermal efficiency (see Clause 5.40) and related markings of only those furnaces whose efficiencies are not regulated in the U.S. by the Energy Policy Act and Conservation Act of 1975 and the National Energy Conservation Policy of 1978, or not covered in Canada by Clause 13, when connected to a single phase electrical supply. Note: At the time of printing, federal energy acts in the U.S. regulate the efficiency (heating capacity) of furnaces having input ratings less than 225 000 Btu/h (65 941 W). 1.5 Examination and testing of undefined furnace types A furnace of a type not specifically defined in this Standard may be subjected to such examination and tests as deemed necessary by the certification body to determine compliance with the intent of this Standard. 1.6 Furnace with draft hood and automatic vent damper device This Standard applies to a furnace that is factory-equipped with both a draft hood and an automatic vent damper device, referred to as a vent damper device from here on. 1.7 Units of measurement Except as noted in Clauses 4.22.1 and 4.26.2, if a value for measurement as given in this Standard is followed by an equivalent value in other units, then the first stated value is regarded as the specification. 1.8 Reference to psi gauge pressures All references to "psi" throughout this Standard are considered gauge pressures unless otherwise specified. 1.9 Provisions for furnace with optional listed conversion kit Special construction provisions applicable to a furnace designed for use with an optional listed conversion kit are outlined in Annex H. 1.10 Referenced standards and jurisdictional requirements Clause 2 contains a list of standards specifically referenced in this Standard. Clause 2 includes both U.S. and Canadian reference standards where applicable. It is the responsibility of the user of this Standard to determine which referenced standard applies based on the requirements of the authority having jurisdiction at the location of the installation; however, a furnace for use in a particular country only should comply with the applicable referenced standard for that country. 1.11 Electrical equipment and wiring provisions Clause 4.17 is unique to the U.S. The Canadian electrical equipment and wiring provisions are contained in CSA C22.2 No. 3 or CSA C22.2 No. 60335-2-102. 1.12 Provisions for furnaces at high altitudes Special construction provisions applicable to furnaces designed to operate at altitudes over 2000 ft (610 m) are outlined in Annex K. 1.13 Units of measurement The values given in US customary units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only. 1.14 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.