Conn. Agencies Regs. § 29-232-100
Each automatically fired hot water heating boiler with heat input greater than 400,000 BTU/HR shall have an automatic low-water fuel cutoff which has been designed for hot water service, and it shall be so located as to automatically cut off the fuel supply when the surface of the water falls to the level established below.
As there is no normal waterline to be maintained in a hot water heating boiler, any location of the low-water fuel cutoff above the lowest safe permissible water level established by the boiler manufacturer is satisfactory.
A coil-type boiler or a watertube boiler with heat input greater than 400,000 BTU/HR requiring forced circulation to prevent overheating of the coils or tubes shall have a flow-sensing device installed in the outlet piping in lieu of the low-water fuel cutoff required above to automatically cut off the fuel supply when the circulating flow is interrupted.
Conn. Agencies Regs. § 29-232-100