N.Y.C. Admin. Code § 27-805: § 27-805 General requirements.

Clearances from combustible construction in walls, partitions and ceilings adjacent to combustion or heating equipment shall not be less than that tabulated in reference standard RS 14-15, provided the following conditions are met:

(a) All clearances shall comply with the requirements specified in section 27-792 of article one of this subchapter.

(b) Heating and combustion equipment which has been tested in accordance with the applicable standards listed in reference standard RS-14, shall be installed with the clearances determined by such tests.

(c) Equipment which has been approved, as provided in section 27-135 of article eight of subchapter one of this chapter, shall be installed in accordance with the conditions of such approval.