CSA/ANSI Z21.10.1-26/CSA 4.1-2026

Gas water heaters, volume I, storage water heaters with input ratings of 75 000 Btu/h or less

Preface This is the ninth edition of CSA/ANSI Z21.10.1/CSA 4.1, Gas water heaters, volume I, storage water heaters with input ratings of 75 000 Btu/h or less . It supersedes the previous editions published in 2019, 2017, 2014, 2013, 2009, 2004, 2001, and 1998. This Standard applies to newly produced, automatic storage water heaters having input ratings of 75 000 Btu/h (21 980 W) or less, referred to as "water heaters" or "appliances" in this Standard, and constructed entirely of new, unused parts and materials. The following are the major changes to this edition: a) Clause 1 has been revised to clarify applicability with respect to fuel types, installation environments (including manufactured homes, park model trailers, recreational vehicles, and outdoor installations), and combination potable water/space heating applications; b) Clause 4 has been revised and expanded to clarify requirements for materials, corrosion resistance, component accessibility, burner construction, venting interfaces, condensate management, and protection against combustion products; c) Clauses 4.1, 4.2, 4.24, 4.32, and 4.33 have been updated to strengthen provisions applicable to direct vent and Category II, III, and IV water heaters, including venting materials, condensate disposal, vent-air intake systems, and installation documentation; d) Clauses 4.1, 4.15, 4.16, 4.30, and 4.34 have been revised to improve alignment and clarity of requirements applicable to water heaters intended for installation in manufactured homes, park model trailers, and recreational vehicles; e) Clauses 4.10 and 4.21 have been revised to update requirements for automatic gas ignition systems, automatic gas shutoff systems, and temperature-limiting devices to reflect current safety expectations and referenced component standards; f) Clause 4.31 has been revised to clarify requirements for electrical construction, wiring methods, protection, marking, and evaluation of low-voltage, line-voltage, and direct-current systems; g) Clauses 4.33 and 4.34 have been revised to improve clarity, consistency, and usability of installation instructions, operating instructions, warning statements, rating plate information, and safety markings; and h) Clause 5 has been revised to improve clarity of test conditions, installation configurations, and evaluation methods, including provisions related to venting systems, damper devices, and direct vent water heaters. This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard. This Standard was prepared by the Subcommittee on Standards for Gas-Fired Water Heaters, 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 newly produced, automatic storage water heaters having input ratings of 75 000 Btu/h (21 980 W) or less, referred to as "water heaters" or "appliances" in this Standard, and constructed entirely of new, unused parts and materials a) for use with natural gas; b) for use with manufactured gas; c) for use with mixed gas; d) for use with propane; e) for use with LP gas-air mixtures; f) for recreational vehicle installation for use with propane only (see Clause 4.1.26); g) for manufactured home (mobile home) or park model trailer installation i) for use with natural gas only; ii) for use with propane only; and iii) convertible for use with natural gas and propane when provision is made for the simple conversion from one gas to the other (see Clause 4.1.25); h) for recreational vehicle installation convertible for use with natural gas and propane when provision is made for the simple conversion from one gas to the other (see Clause 4.1.26); and i) for use with combination potable water/space heating applications (see Clause 4.1.29). 1.2 Water heaters with heat pipe heat exchangers This Standard applies to water heaters incorporating heat pipe heat exchangers (see Clause 4.4). 1.3 Water heaters with draft hoods and vent damper devices This Standard applies to water heaters with draft hoods that are factory-equipped with automatic vent damper devices, referred to as "vent damper devices" from here on. 1.4 Water heaters with automatic flue damper devices This Standard applies to water heaters of other than the direct vent type that are factory-equipped with electrically operated or mechanically actuated automatic flue damper devices, referred to as "flue damper devices" from here on. 1.5 Items unique to the U.S. Clause 7 contains provisions that are unique to the U.S. 1.6 Items unique to Canada Clause 8 contains provisions that are unique to Canada. 1.7 Optional provisions for listed appliance conversion kits Special construction provisions applicable to a water heater designed for use with an optional listed conversion kit are outlined in Annex F. 1.8 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 designed normative (mandatory) or informative (non-mandatory) to define their application. 1.9 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. 1.10 Pressure references All references to "psi" throughout this Standard are considered gauge pressures unless otherwise specified.