Description

This Standard applies to newly produced gas-fired low-pressure steam and hot water boilers with gas inlet pressure ratings not exceeding 0.5 psi (3.5 kPa) and having input ratings of less than 12,500,000 Btu/hr (3 663 389 W) (see Clause 3, Definitions), hereinafter referred to as boilers*, constructed entirely of new unused parts and materials, for operation at or below the following pressures and temperatures:

• Steam heating boilers
  • 15 psi (103.42 kPa) steam pressure
    
• Hot water heating boilers
  
  • 160 psi (1.10 MPa) water pressure
  • 250 F (121 C) water temperature
• Hot water supply boilers
  
  • 160 psi (1.10 MPa) water pressure
  • 250 F (121 C) water temperature

• a) for use with natural gas;
• b) for use with manufactured gas;
• c) for use with mixed gas;
• d) for use with liquefied petroleum gases; and
• e) for use with LP gas-air mixtures.

This Standard applies to indoor boilers, of other than the direct vent type which are categorized according to vent pressure and temperature as either Category I, Category II, Category III or Category IV (see Clause 3, Definitions), and to outdoor type boilers.

This Standard also applies to direct vent boilers (see Clause 3, Definitions). A direct vent boiler anticipated by this Standard is essentially a balanced flue appliance with the air intake and vent outlet in proximity. Other designs are subjected to such additional tests as believed necessary at the discretion of the testing agency.