501.1 Scope.

    The provisions of this chapter shall govern the materials, design and installation of water heaters and the related safety devices and appurtenances.

    501.2 Water heater as space heater.

    Where a combination potable water heating and space heating system requires water for space heating at temperatures greater than 140°F (60°C), a master thermostatic mixing valve complying with ASSE 1017 shall be provided to limit the water supplied to the potable hot water distribution system to a temperature of 140°F (60°C) or less. The potability of the water shall be maintained throughout the system.

    501.3 Drain valves.

    Drain valves for emptying shall be installed at the bottom of each tank-type water heater and hot water storage tank. The drain valve inlet shall be not less than 3/4-inch (19 mm) nominal iron pipe size and the outlet shall be provided with male garden hose threads.

    501.4 Location.

    Water heaters and storage tanks shall be located and connected so as to provide access for observation, maintenance, servicing and replacement.

    501.5 Water heater labeling.

    All water heaters shall be third-party certified.

    501.6 Water temperature control in piping from tankless heaters.

    The temperature of water from tankless water heaters shall be not greater than 140°F (60°C) where intended for domestic uses. This provision shall not supersede the requirement for protective shower valves in accordance with Section 424.3.

    501.7 Pressure marking of storage tanks.

    Storage tanks and water heaters installed for domestic hot water shall have the maximum allowable working pressure clearly and indelibly stamped in the metal or marked on a plate welded thereto or otherwise permanently attached. Such markings shall be in an accessible position outside of the tank so as to make inspection or reinspection readily possible.

    501.8 Temperature controls.

    Hot water supply systems shall be equipped with automatic temperature controls capable of adjustments from the lowest to the highest acceptable temperature settings for the intended temperature operating range.