"Space heater" as used in §§ 93.20 to 93.25, inclusive, shall mean a heating unit which uses or is designed to use solid, liquid or gaseous fuels, which is designed to heat or is used to heat the area in which it is located, and which when installed is not firmly affixed in a permanent position by a rigid pipe connection, is not permanently connected to a chimney stack or flue and is not permanently vented.
('66 Code, § 60-2)