As used in sections 18-2301 to 18-2315, unless the context otherwise requires:
(1) Air conditioning air distribution shall mean the control of any one or more of the following factors affecting both physical and chemical conditions of the atmosphere within a structure: Temperature, humidity, movement and purity;
(2) Furnace shall mean a self-contained, flue-connected or vented, appliance intended primarily to supply heated air through ducts to spaces remote from or adjacent to the appliance location as well as to the space in which it is located;
(3) Contractor shall mean a holder of a valid certificate of competency for air conditioning air distribution;
(4) Ventilating system shall mean each process of removing air by natural gravity exhauster or mechanical exhaust fan from any space; and
(5) Kitchen exhaust system shall mean a duct system or air passageway for removal of kitchen air contaminates by mechanical means.