Preface The standards set forth herein apply to the second edition of the American National Standard for Direct Gas-Fired Door Heaters, ANSI Z83.17-1990, and supersede corresponding standards therein. Following their preparation by the supervising subcommittee, they were accepted by Accredited Standards Committee Z8 3 and subsequently approved as American National Standard by the American National Standards Institute, Inc. NOTE: Changes, other than editorial, are denote