DRAFT STANDARD C823 20XX 

Performance standard for air handlers in residential space 

conditioning systems 

Note: This draft is under development and subject to change; it should not be used for 

reference purposes.

Published by: 

Canadian Standards Association 

5060 Spectrum Way, Suite 100 

Mississauga, Ontario 

Canada L4W 5N6 

Working draft revised December 22, 2009

1
Preface 

This is the first edition of CSA C823, Performance standard for air handlers in residential space 

conditioning systems. This Standard measures both the air delivery and the electrical energy 

consumption of the space conditioning air handler over a range of static pressures and speed 

control settings. Based on those measurements, performance ratings are developed for the air 

handler for each of its operating control settings using a standardized system resistance curve. 

An annual electrical energy consumption rating is also calculated for the air handler. The actual 

performance and annual electricity use of the air handler may vary from the ratings because of 

differences in how it may be installed and used. 

CSA acknowledges that the development of this standard was made possible, in part, by the 

financial support of Natural Resources Canada (NRCan) and others. 

This Standard was prepared by the Subcommittee on C823, under the jurisdiction of the Technical 

Committee on HVACR 

MMM YYYY 

Notes: 

(1) Use of the singular does not exclude the plural (and vice versa) when the sense allows. 

(2) Although the intended primary application of this Standard is stated in its Scope, it is important to note 

that it remains the responsibility of the users of the Standard to judge its suitability for their particular 

purpose. 

(3) This publication was developed by consensus, which is defined by CSA Policy governing 

standardization — Code of good practice for standardization as “substantial agreement. Consensus 

implies much more than a simple majority, but not necessarily unanimity”. It is consistent with this 

definition that a member may be included in the Technical Committee list and yet not be in full 

agreement with all clauses of this publication. 

(4) CSA Standards are subject to periodic review, and suggestions for their improvement will be referred to 

the appropriate committee. 

(5) All enquiries regarding this Standard, including requests for interpretation, should be addressed to 

Canadian Standards Association, 5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 

5N6. 

 Requests for interpretation should 

(a) define the problem, making reference to the specific clause, and, where appropriate, include an 

illustrative sketch; 

(b) provide an explanation of circumstances surrounding the actual field condition; and 

(c) be phrased where possible to permit a specific “yes” or “no” answer. 

 Committee interpretations are processed in accordance with the CSA Directives and guidelines 

governing standardization and are published in CSA’s periodical Info Update, which is available on the 

CSA Web site at www.csa.ca. 

2 
Technical Committee on Heating 

Ventilating and Refrigeration Equipment 

Insert List here 

3
Subcommittee on C823 

Insert List here 

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Table of Contents 

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1 Scope........................................................................................................................................................

1.1..............................................................................................................................................................

1.2..............................................................................................................................................................

1.3..............................................................................................................................................................

1.4..............................................................................................................................................................

1.5..............................................................................................................................................................

2 Definitions and Abbreviations ...............................................................................................................

2.1 Definitions.........................................................................................................................................

2.2 Abbreviations....................................................................................................................................

3 Reference Publications. .........................................................................................................................

4 Standardized Performance Ratings .....................................................................................................

4.1 Electrical Energy Consumption Ratings........................................................................................

4.2 Annual Electrical Energy Consumption (AECR) rating................................................................

4.3 Air Delivery Performance Ratings ................................................................................................

5 Test Setup..............................................................................................................................................

5.1 General .............................................................................................................................................

5.1.1 .....................................................................................................................................................

5.1.2 .....................................................................................................................................................

5.1.3 ...........................................................................................................Error! Bookmark not defined.

5.1.4 .....................................................................................................................................................

5.1.5 .....................................................................................................................................................

5.1.6 .....................................................................................................................................................

5.1.7 .....................................................................................................................................................

5.1.8 .....................................................................................................................................................

5.1.9 .....................................................................................................................................................

5.1.10 ...................................................................................................................................................

5.1.11 ...................................................................................................................................................

5.2 Outlet duct dimensions and static pressure tap.........................................................................

5.3 Electrical Supply.............................................................................................................................

5.4 Energy Consumption Measurement.............................................................................................

5.5 Test room temperature measurement..........................................................................................

5.5.1 Room Ambient Temperature ..................................................................................................

5.5.2 Maximum Wet Bulb Temperature.................................................Error! Bookmark not defined.

5.6 Equipment Precision and Accuracy.............................................................................................

6 Performance Tests...............................................................................................................................

6.1 Test Method — Overview................................................................................................................

6.2 Select speed setting for test ..........................................................................................................

6.3 Apply Power to the air handler .....................................................................................................

6.4 Adjustment of static pressure.......................................................................................................

6.5 Record test measurements ...........................................................................................................

6.6 Adjust the balancing fan to obtain the next test pressure..........................................................

6.7 Calculate standard air flow and static pressure from test data .................................................

6.8 Plot performance curves for each test condition ........................................................................

7 Air Flow measurement apparatus .......................................................................................................

7.1 Nozzle chamber air flow measuring apparatus based on ANSI/AMCA Standard 210-07 | 

ANSI/ASHRAE 51-07 Figure 12 setup..................................................................................................

7.2 Nozzle Airflow Measuring Apparatus based on ASHRAE 37 setup...........................................

7.2.1 .....................................................................................................................................................

7.2.2 .....................................................................................................................................................

7.2.3 .....................................................................................................................................................

7.2.4 .....................................................................................................................................................

7.2.5 .....................................................................................................................................................

5
7.2.6 .....................................................................................................................................................17

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7.3 Measurements and calculations with the air handler operating ...............................................

7.4 Standby Power Consumption Measurement...............................................................................

8 Reference System for Performance Ratings.......................................................................................

8.1 General .............................................................................................................................................

8.2 Full load space heating mode........................................................................................................

8.3 Ratings for other operating modes ...............................................................................................

8.4 Adjustments for airhandlers with Multi-Stage Heating and/or Cooling Capacities..................

9 Minimum and Premium Performance Requirements .........................................................................

9.1 Minimum performance requirements for an air handler .............................................................

9.2 Minimum performance requirements for designation as a premium air handler.....................

6 
CSA C823 Performance standard for air handlers 

in residential space conditioning systems 

1 Scope 

1.1 

This Standard applies to ducted air handler units that are used to supply and/or circulate 

conditioned air in residential central space conditioning systems such as furnaces, heat pumps, 

combination airhandlers and fan coils. 

1.2 

This Standard describes test procedures, test setups and calculations required to determine 

performance ratings for air delivery and electrical energy consumption of air handlers. It does not 

address thermal performance ratings for the air handler system. 

1.3 

This standard does not apply to draft inducer fans, exhaust fans, or heat/energy recovery 

ventilators. 

1.4 

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

information. 

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. 

2 Definitions and Abbreviations 

2.1 Definitions 

The following definitions apply in this Standard: 

Air handler — a space conditioning package that is designed to supply heating and/or cooling 

through a system of ducts with air as the heat transfer medium. It may also circulate air without 

addition or removal of heat and it may be used to provide filtration, humidification, etc. 

Rated voltage — the specified voltage of the unit under test, in Volts, as stated on the unit 

nameplate. 

7
Standard air — air with a standard density of 1.2 kg/m3

 (0.075 lbm/ft3) 

Standard air has a ratio of specific heats of 1.4 and a viscosity of 1.8185*10-3 Pa.s (1.222*10-5 

lbm/ft-s). Air at 20 °C (68 °F) temperature, 50% relative humidity, and standard barometric 

pressure has the properties of standard air, approximately. 

Standard barometric pressure — 101.325 kPa (29.92 in. Hg) 

Unit under test (UUT) — the specific unit sample used for all tests in this Standard 

2.2 Abbreviations 

AMCA:The Air Movement and Control Association International, Inc. 

CSA: Canadian Standards Association 

AHRI: Air-conditioning, Heating, and Refrigeration Institute 

HRAI: Heating Refrigeration & Air Conditioning Institute of Canada 

NRCan: Natural Resources Canada 

3 Reference Publications. 

ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07, 

Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating

ANSI/ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) 

Std 37-2005 

Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment 

 

CAN/CSA C62301 

”Household electrical appliances – Measurement of standby power”. 

4 Standardized Performance Ratings 

Performance ratings shall be calculated based upon the results of tests carried out in accordance 

with this Standard. 

4.1 Electrical Energy Consumption Ratings 

The Electricity consumption rating for each HVAC function shall be reported as follows: 

ECh = Electrical energy consumption rating for operation in heating mode, (Refer to Clause 8.2) 

EChreduced = Electrical energy consumption rating for operation in reduced heating mode 

ECc = Electrical energy consumption rating for operation in cooling mode, (Refer to Clause 8.3) 

ECcreduced = Electrical energy consumption rating for operation in reduced cooling mode 

ECcirc = Electrical energy consumption rating for operation in circulation mode, (Refer to 

Clause 8.3)

ECstdby = Electrical energy consumption rating for standby mode, (Refer to Clause 7.4) 

8 
4.2 Annual Electrical Energy Consumption (AECR) rating 

A standardized annual electrical energy consumption rating for the air handler shall be calculated 

as follows: 

AECR = AHeatH* ECh + AHeatHreduced* EChreduced +ACoolH*ECc +ACircH*ECcirc +AStbyH*ECstdby

Where 

HCR = Heating capacity ratio (rated heat output in the lowesr capacity mode / rated full heat 

output). If HCR is ≤ 0.35, then use 0.35. 

CCR=Cooling capacity ratio (rated cooling output in the lowest capacity mode / rated full cooling 

output) If CCR is ≤ 0.35, use 0.35. 

AECR = Annual electricity consumption rating for the air handler in kWh 

SNHHC = Standardized National Heating Hours for Canada = 2000 hours

AHeatH = Annual heating hours (air-handler operating) 

AHeatHreduced = Annual reduced capacity heating hours (air-handler operating) 

SNCHC = Standardized National Cooling Hours for Canada = 400 hours 

ACoolH = Annual cooling hours (air-handler operating) 

ACoolHreduced = Annual reduced capacity cooling hours (air-handler operating) 

ACircH = Annual circulating hours (air-handler operating) 

AStbyH = Annual standby hours (air-handler not operating) 

Table 1 - Standardized Annual Operating Hours 

NOTE: Applicable to Canada 

AHeatH high AHeatH reduced 

ACoolH 

high 

ACoolH reduced ACircH AstbyH 

Single-stage heating 

Without Constant 

Circulation 

SNHHC 0 SNCHC 0 0 

8760-

AHeatHhighACoolHhigh 

Single-stage heating 

With Constant 

Circulation 

SNHHC 0 SNCHC 0 

8760-

AHeatHhighACoolHhigh 0 

Multi-stage heating 

with single stage 

cooling Without 

Constant Circulation 

0.1*SNHHC 0.9*SNHHC/HCR SNCHC 0 0 

8760-

AHeatHhighAHeatHreducedACoolHhigh 

Multi-stage heating 

and single stage 

cooling With Constant 

Circulation 

0.1*SNHHC 0.9*SNHHC/HCR SNCHC 0 

8760-

AHeatHhighAHeatHreducedACoolHhigh 

0 

Single stage heating 

and multi-stage 

cooling Without 

SNHHC 0 0.1*SNCHC 0.9*SNCHC/CCR 0 

8760-

AHeatHhighACoolHhigh9
Constant Circulation ACoolHreduced

Single stage heating 

and multi-stage 

cooling With Constant 

Circulation 

SNHHC 0 0.1*SNCHC 0.9*SNCHC/CCR 

8760-

AHeatHhighACoolHhighACoolHreduced

0 

Multi-stage heating 

and cooling Without 

Constant Circulation 

0.1*SNHHC 0.9*SNHHC/HCR 0.1*SNCHC 0.9*SNCHC/CCR 0 

8760-

AHeatHhighAHeatHreducedACoolHhighACoolHreduced

Multi-stage heating 

and cooling With 

Constant Circulation 

0.1*SNHHC 0.9*SNHHC/HCR 0.1*SNCHC 0.9*SNCHC/CCR 

8760-

AHeatHhighAHeatHreducedACoolHhighACoolHreduced

Editorial note: The annual hourly multipliers in the above formula will need to be developed by 

the C823 TSC 

4.3 Air Delivery Performance Ratings 

The air delivery performance rating in l/s per W (cfm per W) shall be reported for each control 

speed setting. For multi-stage systems that provide heating or cooling with different capacities 

and use different air delivery settings for each step of capacity, refer to clause 8.4.: 

AHRh = Air delivery performance rating for operation in heating mode, (Refer to Clause 8.2) 

AHRc = Air delivery performance rating for operation in cooling mode, (Refer to Clause 8.3) 

AHRcirc = Air delivery performance rating for operation in circulation mode, (Refer to Clause 8.3) 

5 Test Setup 

5.1 General 

10 
5.1.1 

The air handler shall be installed in the test facility using the control settings and components 

supplied by or specified by the manufacturer. 

Note: There is no need to supply fuel or install venting components for any tests performed to this standard. 

5.1.2 

The unit under test shall not be modified during or between tests. Changes may be made to 

control settings as specified by the manufacturer to obtain different operating conditions for test 

purposes. 

5.1.4 

For testing, the outlet plenum of the air handler shall be connected to an air flow measuring 

apparatus using an outlet duct as specified in clause 5.2. 

5.1.5 

If the air handler is laid down for the test to obtain horizontal flow into the air measuring 

apparatus, inspect the air moving components to ensure that the test setup has not distorted or 

impaired the motor-to-blower connections, fan wheel-to-fan housing clearances or blower-tochassis connection. The orientation of the blower wheel axis shall be maintained for the test. 

5.1.6 

Prepare the return air intake for the test. If the air handler is designed for multiple inlet 

configurations to provide installers with a choice in selecting the return air intake locations, the 

bottom inlet configuration shall be used. For air handlers with fixed return air inlet locations, a 

return air cutout that complies with the manufacturer’s dimensional specifications shall be made. 

5.1.7 

An inlet duct with dimensions that match the return air inlet connection with a length of 2.5 

equivalent duct diameters shall be secured to the return air connection of the air handler. A static 

pressure tap shall be installed on the inlet duct at a distance of 0.5 ± 0.25 equivalent diameters 

from the entry to the air handler. That static pressure tap shall be used to determine the inlet 

static pressure to the air handler which shall be used as the point of reference for determining 

differential static pressure across the air handler during all tests. 

Note: Refer to Figure 1 for details regarding fabrication of the inlet static tap. and to clause 5.2 for 

identification of the location of the outlet pressure tap 

5.1.8 

A suitable electrical power supply shall be connected to the air handler as per clause 5.3. 

5.1.9 

Instrumentation to measure the electrical energy used by the air handler shall be connected in 

accordance with clause 5.4. 

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5.1.10 

The air handler controls and/or wiring connections to “speed” taps shall be adjusted to select the 

operating condition to be tested. 

Note: Blower “speed” taps may need to be altered to allow for testing of the air handler at all available 

settings.

5.1.11 

No air filters shall be installed during tests performed to this Standard. 

Note: An allowance for a representative air filter pressure drop is incorporated into the static pressure used 

for the performance ratings. 

5.2 Outlet duct dimensions and static pressure tap 

The air supply outlet from the air handler shall be connected to an air measuring apparatus using 

a duct that is fabricated in accordance with the dimensions shown in Figure 1 and secured to the 

air handler outlet connection. The static pressure taps illustrated in Figure 1 shall be used to 

measure the outlet static pressure from the air handler for all tests. 

Figure 1 Outlet duct showing reference location for outlet static pressure tap (Source – ASHRAE 

37) 

12 
Notes: Recommended Practices for Static Pressure Measurements using Figure 1 

1 A tap should be located at the center of each face of the (each) plenum, if rectangular, or at four evenly 

distributed locations along the perimeter of an oval or round plenum. 

2 The pressure taps should consist of 6.25 mm (0.25 in.) diameter nipples soldered to the outer plenum 

surfaces and centered over 1 mm (0.040 in.) diameter holes through the plenum. The edges of these holes 

should be free of burrs chamfers and other surface irregularities. 

5.3 Electrical Supply 

The electrical supply to all electric components of an air handler shall be maintained within ±1 

percent of the nameplate voltage for all tests. If a voltage range is used for nameplate voltage, the 

electrical supply shall be maintained within ±1 percent of the mid-point of the nameplate voltage 

range. If a dual voltage is used for nameplate voltage, the electrical supply shall be maintained 

within ±1 percent of the higher voltage. 

5.4 Power and Energy Consumption Measurement 

Instruments shall be installed to measure the quantity of electrical energy supplied to the air 

handler. The electrical power and energy used by the circulation blower motor shall also be 

measured separately (sub-metered). Electrical power and energy consumption shall be expressed 

in units of kilowatts or kilowatt-hours as applicable. Electrical measurements shall be made in 

compliance with CAN/CSA C62301. 

5.5 Test room temperature measurement 

In the test room, a thermocouple or other temperature sensing device shall be installed with the 

junction or sensing element shielded from direct radiation from the air handler and positioned at 

the vertical midpoint of the air handler at a perpendicular distance of 600 mm (24 in) from any 

surface of the air handler. 

5.5.1 Room Ambient Temperature 

The ambient air temperature of the test room shall be maintained between 18°C and 27°C for all 

tests. During any test performed at a particular operating speed setting the room ambient 

temperature shall not vary by more than ± 3°C. 

5.6 Equipment Precision and Accuracy 

The level of accuracy and the precision of the measurement equipment to be used shall be in 

accordance with Table 1. 

6 Performance Tests 

6.1 Test Method — Overview 

The basic approach in this standard is to develop performance curves for the air handler to 

characterize its air delivery and energy consumption for each available blower speed over the 

range of operation that may be encountered after it is installed. The principal reference standard 

method, ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07 has been widely using within the 

HVAC industry to determine the performance of fans and blowers. It provides detailed procedures 

and calculations that are used to produce full performance curves that characterize fan 

performance from free air flow to shutoff. 

In this Standard, certain measurements specified in the reference standard (e.g. blower speed 

measurements) are not required and there is no need for full performance curves for all speed 

settings. The measurements are used to develop performance curves that describe the air 

handler performance over a narrower range of static pressures than a full performance curve. 

Once the air handler performance curves are known, a reference system load curve is 

superimposed. The intersection of the air handler performance curves and the reference system 

13
load curve identifies the operating points that are used for performance ratings. 

Notes: 

1 Not requiring measurement of blower speed and only requiring performance curves within the region 

defined by the reference system curves simplifies the test setup and streamlines the testing. 

2 This Standard identifies ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07as a reference Standard, but it 

allows for different air flow testing setups to be used provided that the accuracy specifications (Table 1) are 

satisfied. This recognizes that other airflow measurement techniques may be available. 

6.2 Select speed setting for test 

The controls of the air handler shall be adjusted and/or speed taps shall be changed to obtain the 

desired operating setting as described in 5.1.10 

Note: tests do not need to be run at conditions that the appliance cannot operate at in the field.

6.3 Apply Power to the air handler 

Apply power to the HVAC air handler as specified in 5.3 

6.4 Adjust static pressure 

Start the nozzle chamber balancing fan and adjust its controls to obtain the desired static 

pressure across the air handler for the test 

6.5 Record test measurements 

After all readings have stabilized, record nozzle differential pressure, static pressure, electrical 

measurements. 

Stabilization is demonstrated by a change of no more than 2% in the measured electricity 

consumption, static pressure and calculated air flow over a minimum of three sets of readings 

approximately equally spaced over a period of at least 1 minute. 

COMMENT: The committee is open to review this statement based on actual lab measurement 

data.

6.6 Adjust the balancing fan to obtain the next test pressure 

After acceptable stabilized conditions have been achieved and recorded, adjust the chamber 

balancing fan to obtain a different test pressure, and repeat 6.5. 

Note: It is recommended that the test pressures be varied in increments of not more than 25 Pa over the 

region of interest to adequately characterize the performance curve 

6.7 Calculate standard air flow and static pressure from test data 

Using the appropriate calculations (that will be different depending on the exact test configuration 

that is used), calculate the air flow and external static pressure for each test and correct the 

calculations to standard air density. 

Note: Examples of two different variations of a nozzle test setup are shown in section 7. The calculations for 

an ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07 Figure 12 setup are provided in 7.1 of this Standard. 

For further detail, refer to section 7 of ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07. Calculations for 

other test setups will rely on the calibration report for that test setup that will be required to verify 

compliance with the accuracy requirements of Table 1. 

14 
6.8 Plot performance curves for each test condition 

Using the data from the tests, plot static pressure and power consumption versus flow for each 

control system speed setting. These will be used with the standard system curve to produce 

standard performance ratings (refer to section 8). 

7 Air Flow measurement apparatus 

Various airflow measurement methods may be used, provided that the calibrated airflow 

measurement accuracy is within the tolerance limits specified in Table 1. Two different examples 

of acceptable airflow measurement setups are provided in this section. 

7.1 Nozzle chamber air flow measuring apparatus based on ANSI/AMCA Standard 

210-07 | ANSI/ASHRAE 51-07 Figure 12 setup 

min.

mm mm

in. in.

Notes for Figure

1. Dotted lines on fan inlet indicate an inlet bell and one equivalent duct diameter which may be used for inlet duct 

simulation. The duct friction shall not be considered. 

2. Dotted lines on fan outlet indicate a uniform duct 2 to 3 equivalent diameters long and of an area within ±1% of 

the fan outlet area and a shape to fit the fan outlet. This may be used to simulate an outlet duct. The outlet duct 

friction shall not be considered. 

3. The fan may be tested without an outlet duct in which case it shall be mounted on the end of the chamber. 

4. The variable exhaust system may be an auxiliary fan or a throttling device. 

5. The distance from the exit face of the largest nozzle to the downstream settling means shall be a minimum of 2.5 

throat diameters of the largest nozzle. 

6. Dimension J shall be at least 1.0 times the fan equivalent discharge diameter for fans with axis of rotation 

perpendicular to the discharge flow and at least 2.0 times the fan equivalent discharge diameter for fans with axis 

of rotation parallel to the discharge flow. Warning! A small dimension J may make it difficult to meet the criteria 

given in Annex A. By making dimension J at least 0.35M this condition is improved, as well as meeting the 

criteria given in section 5.3.1 for any fan. 

7. Temperature td2 may be considered equal to td5. 

8. For the purpose of calculating the density at Plane 5 only, Ps5 may be considered equal to Ps7. 

15
Figure 2: Nozzle chamber airflow apparatus (from Figure 12 of ANSI/AMCA Standard 210-07 -

ANSI/ASHRAE 51-07) 

Flow and Pressure Formulae for Figure 2 

*Q 2 Y  P

5 CA

5

 6

 

 

2

 

P P v v 

Q Q5

5  



 



 



P 0 t1 

V Q

A 2

2 2

 



 









 



 



PPP t2 s7 v  

* P V

2 v2

2

2

 2





 



 

PP P t t2 t   1

P PP s t   v

*The formulae given above are the same in both the SI and the I-P systems, except for Q5 and 

Pv2: In the I-P version, the constant 2 is replaced with the value 1097.8. 

7.2 Nozzle Airflow Measuring Apparatus based on ASHRAE 37 setup 

As shown in Figure 3, this apparatus is a simplified version of the ANSI/AMCA ANSI/ASHRAE 

Figure 12 setup. It consists basically of a receiving chamber and a discharge chamber separated 

by a partition in which one or more nozzles are located. Air from the equipment under test is 

conveyed via a duct to the receiving chamber, passes through the nozzle or nozzles, and is then 

exhausted to the test room. 

7.2.1 

The nozzle air flow measuring apparatus and its connections to the equipment outlet shall be 

sealed so that air leakage does not exceed 1.0% of the air flow rate being measured. 

7.2.2 

 The center-to-center distance between nozzles in use shall be not less than three times the throat 

diameter of the largest nozzle, and the distance from the center of any nozzle to the nearest 

discharge or receiving chamber side wall shall be not less than 1.5 times its throat diameter. 

16 
7.2.3 

 Diffusers shall be installed in the receiving chamber located at least 1.5 times the largest nozzle 

throat diameter upstream of the partition wall. Diffusers in the discharge chamber shall be located 

at least 2.5 times the largest nozzle throat diameter downstream of the exit plane of the largest 

nozzle. 

7.2.4 

An exhaust fan, capable of providing the desired static pressure at the equipment outlet, shall be 

installed in one wall of the discharge chamber, and a means shall be provided to vary the capacity 

of this fan. 

7.2.5 

The static pressure drop across the nozzle or nozzles shall be measured with a manometer or an 

electronic pressure transducer. One side of the pressure measuring device shall be connected to 

four manifolded pressure taps installed within the receiving chamber. The other side of the 

pressure measuring device shall be connected to four manifolded pressure taps installed within 

the discharge chamber. Alternatively, the velocity head of the air stream leaving the nozzle or 

nozzles may be measured by a pitot tube as shown in Figure 2, but when more than one nozzle is 

in use, the pitot tube reading shall be determined for each nozzle. 

Note: Recommendations on how to fabricate and manifold the static pressure taps, if used in measuring air 

volume rate, are provided in ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07. 

Guidance on the placement of the static pressure taps and the position of the diffusion baffle relative to the 

receiving chamber inlet is provided in Figure 12 of ANSI/AMCA Standard 210-07 | ANSI/ASHRAE 51-07. 

7.2.6 

Means shall be provided to determine the air density at the nozzle throat. 

Figure 3 Nozzle chamber air flow measurement apparatus used in ASHRAE 37 

17
7.3 Measurements and calculations with the air handler operating 

Measurements and calculations shall be performed with the speed controls adjusted to the 

manufacturer’s default settings that characterized the performance of the unit, including: 

1. Full-output heating mode, 

2. Minimum output heating mode (if applicable) 

3. Circulation mode 

4. Full output cooling mode (each rated cooling capacity) 

5. Reduced output cooling mode (if applicable, each rated cooling capacity) 

7.4 Standby Power Consumption Measurement 

With the air handler installed and powered, but with the automatic controls adjusted to shut off 

the air flow, the total electric power consumption of the air handler unit shall be determined in 

accordance with CAN/CSA Standard C62301”Household electrical appliances – measurement of 

standby power”. 

8 Reference System for Performance Ratings 

8.1 General 

The system static resistance for a simple distribution duct system is approximately proportional 

to the square of the air flow rate over the range of flows that is normally used in residential HVAC 

systems. Systems with higher capacities use higher air flows, but are intended for use with larger 

ducts. 

8.2 Full load space heating mode 

The reference system for performance ratings is characterized as one that presents a system 

pressure of 125 Pa (0.5 in) when operating at the full load space heating mode. Accordingly, the 

ratings of the air handler for the full output heating mode are taken from the intersection of the air 

flow performance curve for the default heating tap and a pressure differential of 125 Pa (0.5 in). 

For an air handler system such as a furnace that has a specified temperature rise, if there is no 

designated default space heating control setting or speed tap, the heating mode setting shall be 

deemed to be the lowest control setting that provides sufficient air flow at 125 Pa that would be 

needed to achieve the midpoint or lower of the specified air temperature rise. 

The standard air flow required to achieve the midpoint of the specified temperature rise shall be 

calculated based on dry air at standard air conditions and the rated heating capacity of the unit. 

8.3 Ratings for other operating modes 

The ratings for all other operating mode settings shall be determined from the intersection of the 

rating system load curve and the performance curve for the specific operating mode or speed 

setting. The system load curve is as follows 

Ps = K Q2

 

Where 

Ps = Pressure differential 

K = A constant that characterizes the system 

Q = Air flow in l/s (cfm) 

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For each air handler, the K and Q values will be different. In all cases, the system load curve will 

be determined from the rating point defined in clause 8.2 

8.4 Adjustments for airhandlers with Multi-Stage Heating and/or Cooling 

Capacities 

For air handlers that have multi-stage capacity for heating and/or cooling, performance curves 

and standardized performance ratings are required for each stage of air flow. 

For air handlers that have variable capacity for heating and/or cooling, performance curves and 

standardized performance ratings are required at the minimum and maximum stage of air flow. 

9 Minimum and Premium Performance Requirements 

9.1 Minimum performance requirements for an air handler 

Reserved 

9.2 Minimum performance requirements for designation as an electrically efficient 

air handler 

Reserved 

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Table 1 

Equipment Precision and Accuracy Requirements 

(See Clause 5.10 and 6.3) 

 

Item Instrument accuracy Instrument Precision* 

Atmospheric pressure ± 0.3 kPa (±0.1 in Hg) ± 0.17 kPa (± 0.005 in Hg) 

External static pressure rise ± 2 Pa (± 0.01 in w.c.) ± 1 Pa (± 0.005 in w.c.) 

Airflow ± 2% of reading 

Electrical Power ± 1% of reading or 0.5 W 

(whichever is greater) 

± 0.5% of reading or 0.5 W 

(whichever is greater) 

Time ± 0.5 s/h ± 0.25 s/h 

Inlet and outlet air temperatures ± 0.1 °C (± 0.2°F) ± 0.06 °C (± 0.1°F) 

*The smallest scale division on an instrument used shall not be more than twice the specified precision. 

 

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Annex A 

Reporting Template 

Note: This Annex is not a mandatory part of this Standard. 

 Testing Agency: Product Identification:

 Date Issued: Serial Number:

 Manufacturer: Options Installed:

Nameplate Information Volts Amps

Rated Heating Capacity kW Btu/h

Rated Cooling Capacity kW Btu/h

Electrical

ECh W

ECc W

ECcirc W

ECstdby W

Air Delivery

AHRh l/s.w

AHRc l/s.w

AHRcirc l/s.w

Daily Electricity use for water heating 

(E24h-SUT) kWh

Add second curve for the electrical curves, or add elect. scale as second axis

Type of system

Fuel type

Blower/Motor:

Other:

Test Agency Comments:

Conversions: Reference Report:

249 Pascals = 1" of Water 1 kW = 3413 Btu/h 

 Draft Air Handler Specification Summary (Ref. CSA Standard C823)

Annual Electrical Energy Consumption Rating XXXX kWh

 Performance Ratings

Description of key air handler components

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