§ 156.46  HOT WATER SUPPLY SYSTEMS.
   (A)   All domestic hot water supply systems employing a storage tank, whatever the heat source and whether controlled manually or automatically, hereafter installed or if already existing when the tanks are changed or replaced, shall be equipped with effective devices to relieve excess pressure and excess water temperature, which two functions may be combined in one device. The device shall be constructed in brass or other corrosion resisting material and shall be approved by the Plumbing Inspector.
   (B)   The pressure relief device shall be equipped with a means of testing its free action in place. Its inlet shall not be less than one-half inch and its outlet shall not be less than one-half inch. The size of the relief valve shall be not less than the connecting supply pipe. The outlet shall be piped to the nearest fixture or floor drain with iron pipe size brass pipe or heavy copper tubing. The pressure relief device shall be located on the cold water inlet and as close as practical to the storage tank. The circulating pipe between the storage tank and the heating unit shall be iron pipe size brass or copper pipe.
   (C)   The temperature relief device may accomplish its purpose by shutting off the supply of heat or by discharging hot water and must be so installed that the heat responsive portion will be exposed to the maximum water temperature either in the storage tank or the hot water supply line. If it is of the type which shuts off the supply of heat, it shall be independent of any thermostatic control of water temperature and must be so designed that it will have to be reset manually in order to put it back in service after it has operated.
   (D)   The excess pressure relief valves will be required on instantaneous types of heaters employing no storage tank.
(1967 Code, § 16-17)  Penalty, see § 10.99