§ 18-29-504.1 Antisiphon devices.
An approved means shall be provided to prevent siphoning of any storage water heater or tank. A cold water 'dip' tube with a hole at the top or a vacuum relief valve installed in the cold water supply line above the top of the heater or tank shall be approved for this purpose. Such a device shall be installed on any water heater or heated water storage tank that supplies a water outlet below the level of the heater.
§ 18-29-504.2 Vacuum relief valve.
Water heaters elevated above the fixtures they serve and tanks connected to such water heaters shall have a vacuum relief valve installed. The vacuum relief valve shall comply with ANSI Z21.22.
(Amend Coun. J. 3-27-02, p. 82090, 3)
§ 18-29-504.3 Energy cutoff device.
All automatically controlled water heaters shall be equipped with an energy cutoff device that will cut off the supply of heat energy to the water tank before the temperature of the water in the tank exceeds 200F (93.3C). This cutoff device shall be required in addition to the temperature and pressure relief valves.
§ 18-29-504.4 Shutdown.
A separate switch shall be provided to terminate the energy supplied to electric hot water supply systems. A separate valve shall be provided to turn off the energy supplied to the main burner of all other types of hot water supply systems.
§ 18-29-504.5 Relief valve.
All storage water heaters operating above atmospheric pressure shall be provided with an approved, self-closing (levered) pressure relief valve and temperature relief valve or combination thereof. The relief valve shall conform to ANSI Z21.22. The relief valve shall not be used as a means of controlling thermal expansion.
§ 18-29-504.5.1 Installation.
Relief valves shall be installed in the shell of the water heater tank. Temperature relief valves shall be so located in the tank as to be activated by the water in the top 6 inches (150 mm) of the tank served. For installations with separate storage tanks, the valves shall be installed on the tank and there shall not be any type of valve installed between the water heater and the storage tank. There shall not be a check valve or shutoff valve between a relief valve and the heater or tank served.
§ 18-29-504.6 Relief valve approval.
Temperature and pressure relief valves (or combinations thereof) and energy cutoff devices shall bear the label of an approved agency and shall have a temperature setting of not more than 200F (93.3C) and a pressure setting not exceeding the tank or water heater manufacturer's rated working pressure. Where a pressure rating of more than 150 psi (1034.25 kPa) is not necessary for the proper function of the domestic hot water system, the pressure rating of the relief valve shall be limited to 150 psi (1034.25 kPa). The relieving capacity of each pressure relief valve and each temperature relief valve shall equal or exceed the heat input to the water heater or storage tank, and shall have the AGA steam temperature rating clearly indicated.
§ 18-29-504.7 Relief outlet waste.*
The outlet of a pressure, temperature or other relief valve shall not be directly connected to the drainage system.
* Note - Coun. J. 3-28-01, p. 55444, 1, this section was mistyped as § 18-29-204.7; corrected but not verified.
§ 18-29-504.7.1 Discharge.
The discharge from the relief valve shall be piped separately to an indirect waste receptor located inside the building. The discharge shall be piped full size and installed in a manner that does not cause personal injury or property damage and that is readily observable by the building occupants. The discharge from a relief valve shall not be trapped. The diameter of the discharge piping shall not be less than the diameter of the relief valve outlet. The discharge pipe shall be installed so as to drain by gravity flow and shall terminate atmospherically not more than 6 inches (150 mm) above the floor. The end of the discharge pipe shall not be threaded.
§ 18-29-504.7.2 Location.
The relief outlet discharge piping shall be installed so that it does not leave the room or enclosure in which the water heater and relief valve are located.
§ 18-29-504.7.3 Materials.
Relief valve discharge piping shall be of those materials listed in Section § 18-29-605.5 for water distribution piping or shall be tested, rated and approved for such use in accordance with ASME A112.4.1. Piping from safety pan drains shall be of those materials listed in Table § 18-29-605.5.
§ 18-29-504.8 Required pan.
Water heaters or hot water storage tanks installed in locations where leakage of the tanks or connections will cause damage shall be installed in a galvanized steel or other metal pan of equal corrosion resistance having a minimum thickness of 24 gauge, 0.0276 inch (0.70 mm) Any water heater installed in a cabinet below a counter shall be provided with a drain pan.
(Amend Coun. J. 3-27-02, p. 82090, 3)
§ 18-29-504.8.1 Pan size and drain.
The pan shall not be less than 1 1/2 inches (40 mm) deep and shall be of sufficient size and shape to receive all dripping or condensate from the tank or water heater. The pan shall be drained by an indirect waste pipe having a minimum diameter of 1 inch (25 mm) or the outlet diameter of the required relief valve, whichever is larger.
§ 18-29-504.8.2 Pan drain termination.
The pan drain shall extend full-size and terminate over a suitably located indirect waste receptor or floor drain.