CSA C191-04 pdf download – Performance of electric storage tank water heaters for domestic hot water service.
1 Scope 1.1 General This Standard specifies requirements related to 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 184 or 284 L (40 or 60 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. In addition, the standby loss test and its associated calculation (see Clause 4.8) may be applied to stationary storage tank water heaters that have a rated capacity of 50 to 454 L (11 to 100 gal). 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. 2 Reference publications This Standard refers to the following publications, and where such reference is made, it shall be to the edition listed below, including all amendments published thereto.
3 Definitions Note: Some of the defined terms listed in this Clause do not appear elsewhere in this Standard but are defined here for informational purposes. The following definitions apply in this Standard: Average water temperature — the average of the water temperature obtained through the use of six thermocouples, each located so as to sense the centre point of six approximately equal volumes of water from the top to the bottom of the tank. Bottom inlet — a type of storage tank water heater whose cold water supply pipe is external to the tank and whose connection is on or near the bottom of the tank. Controlled temperature differential — the difference between the water temperatures in degrees Celsius at the level of the temperature-sensing element of the thermostat at cut-in and cut-out under standby conditions. Cut-in — the time or minimum temperature at which a water heater thermostat has acted to start the application of heat to the water. Cut-in temperature — the minimum water temperature obtained in the top-of-tank for any particular setting of the thermostat. Cut-out — the time or maximum temperature at which a water heater thermostat has acted to stop the application of heat to the water. Cut-out temperature — the maximum water temperature obtained in the top-of-tank for any particular setting of the thermostat. Diffusion ratio — the ratio of the volume of water withdrawn to the actual tank capacity.
Rated voltage — the voltage or range of voltages that appears on the nameplate designating the nominal voltage of the supply circuit on which the water heater is designed to be used. Rated watts input — the power input in watts marked on the element and the nameplate of the water heater at the rated voltage. Shipping container — the complete package when the water heater is shipped. Standby — the condition of operation when no water is withdrawn from the tank and the water temperature is regulated by the thermostats. Storage tank — the water container. For convenience, the term “tank” is used in this Standard. Tank capacity — the measured or actual tank capacity in litres. Thermal insulation — the material provided to reduce the rate of heat loss from the tank and heater elements. Thermocouple probe — a test device inserted in the tank and provided with thermocouples to measure water temperatures at various levels.CSA C191-04 pdf download.
