Section 27-2028. Central heat or electric or gas heating system; when required

Except as otherwise provided in this article, every  multiple  dwelling  and  every tenant-occupied one or two-family dwelling shall be
  provided  with  heat  from  a  central  heating  system  constructed  in
  accordance  with the provisions of the building code and the regulations
  of the department. A system of gas or electric heating provided for each
  dwelling unit may, if approved by the department, be utilized in lieu of
  a central heating system if:
    (1) the system is lawfully in use on July fourteenth, nineteen hundred
  sixty-seven; or
    (2) the system is approved by the  appropriate  city  agencies  having
  jurisdiction  and  is  installed  in  a  structure  or building erected,
  converted, substantially rehabilitated,  or  completely  vacated,  after
  July fourteenth, nineteen hundred sixty-seven.