Water heaters deriving heat from fuels or types of energy other than gas shall be constructed and installed in accordance with the approved standards referenced in Table 501.1(2), Section 505.3, or Section 505.4. Vents or chimneys for such appliances shall be approved types. An adequate supply of air for combustion and for adequate ventilation of heater rooms or compartments shall be provided. Each such appliance shall be installed in a location approved by the Authority Having Jurisdiction and local and state fire-prevention agencies.
Storage-type water heaters and hot water boilers deriving heat from fuels or types of energy other than gas, shall be provided with, in addition to the primary temperature controls, an overtemperature safety protection device constructed, listed, and installed in accordance with nationally recognized applicable standards for such devices and a combination temperature and pressure-relief valve.
Oil-fired water heaters shall be installed in accordance with NFPA 31.
Indirect-fired water heaters shall comply with the applicable sections of the ASME Boiler and Pressure Vessel Code, or to one of the other applicable standards shown in Table 501.1(2). Each water heater shall bear a label in accordance with ASME requirements, or an approved testing agency, certifying and attesting that such an appliance has been tested, inspected and meets the requirements of the applicable standards or code.
An indirect-fired water heater that incorporates a single-wall heat exchanger shall be in accordance with the following requirements:
- The heat transfer medium shall be either potable water or contain fluids recognized as safe by the Food and Drug Administration (FDA) as food grade.
- Bear a label with the word "Caution," followed by
the following statements:
- The heat-transfer medium shall be potable water or other nontoxic fluid recognized as safe by the FDA.
- The maximum operating pressure of the heat exchanger shall not exceed the maximum operating pressure of the potable water supply.
- The word "Caution" and the statements in letters shall have an uppercase height of not less than 0.120 of an inch (3.048 mm). The vertical spacing between lines of type shall be not less than 0.046 of an inch (1.168 mm). Lowercase letters shall be compatible with the uppercase letter size specification.