NAC455C.280. Device for feeding water; automatic cutoff for fuel.

     1. Except as otherwise provided in subsections 4 and 5, each automatically fired steam, vapor system or hot water heating boiler with an input of fuel in excess of 199,999 British thermal units per hour must be equipped with an automatic cutoff for fuel if water is low that is located in such a manner as to cut off automatically the supply of fuel when the surface of the water falls to the lowest safe water line. If a device for feeding water is installed, it must be so constructed that the inlet valve for water cannot feed water into the boiler through the float chamber and so located as to supply requisite water for feeding. For steam boilers, the lowest safe water line must be not lower than the lowest visible part of the water glass.

     2. A device for controlling the feeding of water or fuel may be attached directly to a boiler or for low-pressure steam and hot water boilers, to the tapped opening provided for attaching a water glass directly to the boiler. The water glass must be attached as close as possible to the boiler. The ends of the nipples must be reamed to full-size diameter. The connection from the boiler must be a nonferrous “T” or “Y” joint at least 1/2-inch pipe size between the boiler and the water glass. The straightway tapping of the “T” or “Y” must take the fittings for the water glass. The side outlet of the “T” or “Y” must take the fittings for the fuel cutoff or device for feeding water.

     3. Designs embodying a float and float bowl must have a vertical drain pipe and adequate valving for the straightway valve at the lowest point in the water-equalizing pipe connections by which the bowl and the equalizing pipe can be flushed and the device tested. The straightway valve must be at least 3/4-inch national pipe size.

     4. The cutoff for fuel, if water is low on a hot water heating boiler, may be located anywhere above the lowest safe permissible water level established by the manufacturer of the boiler.

     5. A coil-type or a watertube boiler for hot water which requires forced circulation of water to prevent overheating of the coils or tubes must have a device to sense the flow of water installed in the outlet pipes in place of the cutoff for fuel if water is low. The device must automatically cut off the supply of fuel if the circulating flow of water is interrupted.

     (Added to NAC by Div. of Industrial Relations by R101-02, eff. 12-15-2004)