Drain water heat recovery units

1.1
This Standard specifies requirements for the durability and safety of vertically installed, falling-film drain water heat recovery (DWHR) units.

1.2
This Standard applies to DWHR units of any diameter and length and configuration for use with potable water, and to their components and materials supplied by the manufacturer, their assembly and installation instructions, and their operation after assembly in accordance with these instructions. This Standard does not apply to site preparation or installation procedures.

1.3
This Standard is not intended as a design specification or as an instruction manual for untrained persons.

1.4
In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the standard.
   Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
   Notes to tables and figures are considered part of the table or figure and may be written as requirements.
   Annexes are designated normative (mandatory) or informative (nonmandatory) to define their application.