The rules of this code cover requirements for the assembly,maintenance,and operation of controls and safety devices installed on automatically operated boilers directly fired with gas, oil, gas-oil, or electricity, subject to certain service limitations and exclusions. Use of a gaseous or oil fuel not listed in the definitions has not been evaluated and special considerations may be required. Exclusions (a) Boilers with fuel input ratings of 12,500,000 Btu/hr (3 663 389 w) or above, falling within the scope of NFPA 8501, NFPA 8502, NFPA 8503, and NFPA 8504. (b) Water heaters.