"Gravity warm air heating systems" means one or more warm air furnaces as the source of heating supply, together with all appurtenances and parts thereto, consisting of casings, warm air supply ducts, pipes, stacks and fittings, controls, return air or recirculating ducts, pipes, drops, boxes and fittings, smoke pipes and fittings, registers, borders, faces and grilles, the same being used or intended for heating buildings or parts of buildings in which they have been or may be installed.
(Ord. 421-47. Passed 4-7-47.)