Follow these instructions carefully. A CAUTION Do not connect this furnace to a chimney flue serving a separate appliance designed to burn solid fuel, per American National Standard Z21.476-1986 National Fuel Gas Code. G EFFICIENCY RATING CERTIFIED ama The design of the downflow/horizontal (Fig 1 and 2) gas-fired furnace is AGA certified for natural and propane gas installation on combustible flooring (with optional floor base), in alcoves, attics, crawl spaces, basements, closets or uti