CSA F326:23

Preface  This is the second edition of CSA F326, Residential mechanical ventilation systems . It supersedes the previous edition published in 1991.  The major changes to this edition include the following:  a) This Standard no longer covers the requirements for controlling depressurization and instead requires compliance with CSA F300.  b) Kitchen exhaust requirements have been updated based on ongoing research regarding the contribution of cooking to PM2.5 levels.  c) There have been extensive revisions in organization and format as well as many editorial revisions. CSA Group acknowledges that the development of this Standard was made possible, in part, with the use of specific forms included from the Heating, Refrigeration and Air Conditioning Institute of Canada.  This Standard is considered suitable for use for conformity assessment within the stated scope of this Standard.  This Standard was prepared by the Subcommittee on Ventilation Requirements for Housing, under the jurisdiction of the Technical Committee on Residential Depressurization and the Strategic Steering Committee on Fuels and Appliances, and has been formally approved by the Technical Committee.  This Standard has been developed in compliance with StandardDetails Council of Canada requirements for National StandardDetails of Canada. It has been published as a National Standard of Canada by CSA Group. Scope  1.1 Inclusions  This Standard defines the requirements for performance, installation and application, and performance verification of mechanical ventilation systems. This Standard applies to systems that are capable of providing minimum controlled rates of outdoor air to the habitable spaces of those single-family dwelling units that  a) fall within the Scope of Part 9 of the National Building Code of Canada; and  b) are self-contained with respect to heating, ventilation, and air conditioning.  This Standard also applies to dwelling units that fall outside the scope of Part 9 of the NBC as long as the low flow and high flow rates are provided by a balanced system where the supply and exhaust airflows are within 10% of each other and are self-contained with respect to heating, ventilation, and air conditioning.  This Standard also applies to the installation requirements for ventilation components such as supply and exhaust ventilation fans and associated equipment, including bathroom exhaust fans, kitchen exhaust fans, cooktop hoods with or without ducts, and downdraft exhaust fans intended for operation in the dwelling unit, whether or not a part of a ventilation system conforming to this Standard.  This Standard also applies to the installation requirements for self-contained ducted heat or enthalpy recovery ventilators intended for operation in the dwelling unit, whether or not they constitute a part of a ventilation system conforming to this Standard. The applicable heat or enthalpy recovery ventilators have a maximum rated capacity of not more than 236 L/s (500 cfm).  The amounts of ventilation and exhaust air specified in this Standard are intended to deal with contaminants at the rates of generation normally encountered in residential dwellings. Acceptable indoor air quality also requires that the rate of contaminant generation be controlled. 1.2 Exclusions  The outdoor air is assumed to, in general, be of adequate quality to meet the needs of the occupants.  The outdoor air requirements of this Standard are not intended to provide for the combustion and dilution air needs of vented combustion appliances. These are specified in the StandardDetails referred to in Clause 2.  This Standard does not consider the air supply required for combustion and dilution in fireplaces, required to account for that exhausted through the fireplace flue.  The outdoor air requirements of this Standard are not intended to provide sufficient ventilation for indoor thermal comfort in hot weather.  This Standard does not apply to the installation of recirculating forced air heating and air conditioning systems that are not used for ventilation.  This Standard does not mandate the way in which the occupant operates the system. The rates in operation depend on the preference of the occupants.  In determining the capacity of the mechanical ventilation system, this Standard takes no account of the ventilating effects of uncontrolled air leakage, of natural ventilation through open windows, or of other such openings operated by the occupants.  1.3 Users  This Standard is intended to be used by designers of ventilation systems within the scope of this Standard as well as those responsible for installing and inspecting them.  1.4 Terminology  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 (non-mandatory) to define their application.  1.5 Units of measurement  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.  Note: The values in parentheses are based on a rounded conversion of 2 cfm/L/s and 250 Pa/in w.c., which are deemed to be acceptable for the purpose of this Standard.