**422.47 Water Heater Controls. **
All storage or instantaneous-type water heaters shall be equipped with atemperature-limiting means in addition to its control thermostat to disconnect all ungrounded conductors. Such means shall comply with both of the following:
(1) Installed to sense maximum water temperature.
(2) Be either a trip-free, manually reset type or a type having a replacement element. Such water heaters shall be marked to require the installation of a temperature and pressure relief valve.
*Exception No. 1: Storage water heaters that are identified
**as being suitable for use with supply water temperature of *82°C (180°F) or above and a capacity of 60 kW or above.
*Exception No. 2: Instantaneous-type water heaters that **are identified as being suitable for such use, with a capacity *of 4 L (1 gal) or less.
FPN: See ANSI Z21.22-1999/CSA 4.4-M99,
*Relief Valves *for Hot Water Supply Systems.