Nothing contained herein shall authorize or allow burning which is prohibited by codes, laws, rules or regulations promulgated by the United States Environmental Protection Agency, New York State Department of Environmental Conservation or any other federal, state, regional or local agency. Outdoor boilers, and any electrical, plumbing or other apparatus or device used in connection with an outdoor boiler, shall be installed, operated and maintained in conformity with the manufacturer's specifications and any and all local, state and federal codes, laws, rules and regulations. In case of a conflict between any provision of this subsection and any applicable federal, state or local ordinances, codes, laws, rules or regulations, the more restrictive or stringent provision or requirement shall prevail.