Systems utilizing heat exchangers shall protect the potable water system from being contaminated by the heat transfer medium. Systems that incorporate a single-wall heat exchanger to separate potable water from the heat-transfer fluid shall meet the following requirements:
- Heat transfer medium is either potable water or contains fluids recognized as safe by the Food and Drug Administration (FDA) as food grade.
- A tag or label shall be securely affixed to the heat source with the word, "CAUTION" and the following statements:
- The heat transfer medium shall be 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 listed above 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 not less than compatible with the uppercase letter size specification.