N.Y. Comp. Codes R. & Regs. tit. 12, § 4-1.3 – Application.

(a) Except as otherwise hereinafter provided, this Part (rule) applies throughout the State of New York to all boilers to which Section 204 of the Labor Law applies.
(b) Except as otherwise hereinafter provided, no provision of this Part (rule) is intended to apply in derogation of or to supersede any provision of Industrial Code Part (rule) 14 relating to the construction, installation, inspection and maintenance of steam boilers (also known as 12 NYCRR Part 14).
(c) In conformity with subdivision 5 of section 204 of the Labor Law the provisions of this Part (rule) shall not apply:
1. (1) to a boiler which is subject to inspection by inspectors of boilers under the Department of Transportation;
2. (2) to a boiler located on a farm and used solely for agricultural purposes. Unless in a particular case the commissioner shall otherwise determine, the word farm shall be deemed for the purposes of this Part (rule) to refer to arable land in a rural environment;
3. (3) to a steam or vapor boiler operating at a gage pressure of not more than 15 pounds per square inch, and which is located in a dwelling occupied by less than six families;
4. (4) to a hot water boiler which is located in a dwelling occupied by less than six families;
5. (5) to a boiler subject to inspection or control by a Federal agency.
(d) This Part (rule) shall not apply to a boiler subject to inspection by the New York State Department of Public Service unless section 204 of the Labor Law is determined to apply to such boiler.
Note:
Whenever a dwelling is occupied by less than six families and where, within a portion of one or more of these apartments a professional service (medicine, dentistry, engineering, etc.) or a nonprofessional service (dressmaking, etc.) is being rendered and such remaining portion of the apartment(s) is used as an abode of the individual rendering the service, the boiler located within the dwelling shall be deemed to be exempt. This exception shall not apply when such services are separate and apart from the apartment proper wherein the individual rendering the services resides, such as a store or separate apartment within the dwelling.
(e) The exemptions set forth in section 204 of the Labor Law are based on the location of a boiler. It is subject to inspection when:
1. (1) the boiler is located in a dwelling occupied by six or more families even though the particular boiler serves fewer than six dwellings; or
2. (2) the boiler is located on commercial premises without regard to the number of dwelling units it serves.