Conn. Agencies Regs. § 29-232-95
Each automatically fired steam boiler shall be protected from overpressure by two pressure-operated controls.
Each individual automatically fired steam boiler shall have a safety limit control that will cut off the fuel supply to prevent steam pressure from exceeding the 15 psi maximum allowable working pressure of the boiler. Each control shall be constructed to prevent a pressure setting above 15 psi.
Shutoff valves of any type shall not be placed in the steam pressure connection between the boiler and the controls described above. These controls shall be protected with a syphon or equivalent means of maintaining a water seal that will prevent steam from entering the control. The connections to the boiler shall not be less than 1/4 in. standard pipe size, but where steel or wrought iron pipe or tubing is used, they shall not be less than 1/2 in. standard pipe size. The minimum size of a syphon shall be 1/4 in. standard pipe size or 3/8 in. O.D. nonferrous tubing.
Conn. Agencies Regs. § 29-232-95