As used in this article, the following terms shall have the meanings indicated:
Any equipment, device or apparatus, or any part thereof, which is installed, affixed or situated outdoors for the primary purpose of combustion of fuel to produce heat or energy used as a component of a heating system providing heat for any interior space or water source.
Any vertical structure enclosing a flue or flues that carry off smoke or exhaust from a solid-fuel-fired heating device, especially that part of such structure extending above a roof.