Preface The standards set forth herein apply to the first edition of the Standard for Gas Unit Heaters and Gas-Fired Duct Furnaces, ANSI Z83.8-1996/CGA 2.6-M96, and supersede corresponding standards therein. Following their preparation by the supervising subcommittee, they were accepted by ANSI, the Interprovincial G as Advisory Council, International Approval Services, and the Canadian Gas Association and subsequently approved. NOTE: