Preface

This is the fifth edition of CSA C191, Performance of electric storage tank water heaters for domestic hot water service. It supersedes the previous editions, published in 2004 and 2000 under the title, Performance of Electric Storage Tank Water Heaters for Household Service.

Technological changes since the publication of the previous edition of this Standard have led to the updating of clauses dealing with element Watts densities, test procedures, and standby loss levels. The wooden testing platform has been replaced with concrete.

CSA acknowledges that the development of this Standard was made possible, in part, by the financial support of BC Hydro, the Canadian Electricity Association, Conserve Nova Scotia, Hydro-Quebec, Manitoba Hydro, Natural Resources Canada, and the Ontario Ministry of Energy.

This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard.

Scope

1.1 General
This Standard specifies requirements related to hot water delivery, minimum standby performance, heater element ratings, and marking of electric storage tank water heaters.

1.2 Tank capacity
This Standard applies to stationary storage tank water heaters that have a rated capacity of 50 to 454 L (11 to 100 gal) and are intended for use with pressure systems in residential premises and similar locations. For convenience, the term "water heater" is used in this Standard to refer to such heaters.

1.3 Mandatory language
In CSA Standards, "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. Legends to equations and figures are considered requirements.

1.4 Units of measurement
The values given in SI (metric) units are the standard. The values given in parentheses are for information only. All measurements in gallons refer to imperial gallons.