scope:

This Standard specifies requirements for measuring the heat recovery efficiency and pressure loss for vertically installed, falling-film drain water heat recovery (DWHR) units.

This Standard applies to DWHR units

(a) of any diameter and length;

(b) with a configuration where potable water and drain water flow rate is equal; and

(c) with a flow rate range of 5.5 to 14 L/min. 

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.