Preface This is the fourth edition of ANSI Z21.84, Manually lighted, natural gas, decorative gas appliances for installation in solid-fuel burning appliances. It supersedes the previous editions published in 2012, 2002, and 1999. Scope 1.1 These requirements apply to manually lighted, natural gas, decorative gas appliances for installation in solid-fuel burning fireplaces, (see Clause 3, Definitions), hereinafter referred to as appliances, for use with natural gas only, at a maximum input rating of 90,000 Btu/hr (26 376 W) (except as noted in Clause 4.6, Piezo-electric ignitors), which are constructed entirely of new, unused parts and materials. These appliances do not incorporate a pilot burner or an automatic gas ignition system. The main burner(s) is intended to be lighted by hand each time the appliance is used. The construction of manually lighted, natural gas, decorative gas appliances for installation in solid-fuel burning fireplaces is covered under Clause 4. The performance of manually lighted, natural gas, decorative gas appliances for installation in solid-fuel burning fireplaces is covered under Clause 5. 1.2 Manually lighted, natural gas, decorative gas, appliances for installation in solid-fuel burning fireplaces are not to be thermostatically controlled. 1.3 This Standard does not cover unvented room heaters. 1.4 If a value for measurement as given in this Standard is followed by an equivalent value in other units, the first stated value is to be regarded as the specification. 1.5 All references to \"psi\" throughout this Standard are to be considered gauge pressures unless otherwise specified. 1.6 Clause 2 contains a list of standards specifically referenced in this Standard and sources from which they may be obtained. 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. 1.7 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.