Testing method for measuring the annual fuel utilization efficiency of residential gas-fired or oil-fired furnaces and boilers

1.1 
This Standard specifies a testing method for measuring the annual fuel utilization efficiency (AFUE) and 
electrical energy consumption of residential gas-fired or oil-fired forced-air furnaces, low-pressure 
steam boilers, and hot water boilers.
Note: The test method simulates seasonal space heating.
This Standard includes
a) a testing method for cyclic and part-load performance;
b) methods for interpolating and extrapolating test data; and
c) calculation procedures for establishing seasonal performance.
∆ 1.2 
This Standard applies to furnaces with inputs up to and including 65.94 kW (225 000 Btu/h) and boilers 
with inputs less than 87.92 kW (300 000 Btu/h) intended for use in residential applications. This 
Standard also applies to packaged furnaces with inputs up to and including 65.94 kW (225 000 Btu/h) 
that contain an air conditioner within the same cabinet that has a rated cooling capacity of 19.05 kW  
(65 000 Btu/h) or less. Where the input device (e.g., nozzle) changes the capacity of the appliance, each 
appliance/input device combination shall be tested in accordance with the test procedure.
Note: Oil furnaces may be shipped with multiple nozzles, and AFUE values are required for each nozzle.
1.3 
Typical furnace and boiler classifications covered by this Standard are listed in Tables 1 and 2. This 
Standard applies to the gas- or oil-fired portion of a multifuel burning appliance.
1.4 
This Standard does not take into account the effects of heating system installation variables and 
therefore cannot be used to determine absolute measures of performance for specific installation 
configurations. Accordingly, this Standard is intended to be used for comparing energy consumption 
measurements of furnace and boiler models.
1.5 
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; “may” is used to express an option or that which is permissible 
within the limits of the standard; and “can” is used to express possibility or capability. 

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.
1.6 
The values given in SI (metric) units are the standard. The values given in parentheses are for 
information only.