Preface This is the third edition of CSA B55.2, Drain water heat recovery units . It supersedes the previous editions published in 2012 and 2015. This Standard specifies health and safety requirements for drain water heat recovery (DWHR) units. This Standard was developed in response to the need for a document that specifies safety and performance criteria for DWHR units. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. Scope 1.1 This Standard specifies requirements for the durability and safety of 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. 1.5 The values given in SI units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.