CSA/ANSI Z21.66:23 • CSA 6.14:23

1 Scope 1.1 Applications This Standard applies to the construction, performance, and installation procedures for a newly produced automatic damper device (referred to as “device” in this Standard) constructed entirely of new and unused parts and materials, and designed to be used with a gas-fired appliance listed by a nationally recognized certification body. 1.2 Inclusions This Standard applies to the following automatic damper devices: a) vent; b) flue; c) fireplace chimney; and d) backflow prevention. Flue damper devices have been in use for decades and have been tested and certified to this Standard by many nationally recognized certification bodies. A backflow damper is designed to prevent flue gas from entering idle appliances when part of a positive pressure common vent system. These types of systems are becoming more commonly used in North America. 1.3 Gauge pressure All references to “psi” throughout this Standard are to be considered gauge pressures unless otherwise specified. 1.4 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. Note: See Annex Ffor conversion tables. 1.5 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.