ISO 16494:2014

INTERNATIONAL ISO
STANDARD 16494
First edition
2014-11-01
Heat recovery ventilators and energy
recovery ventilators — Method of test
for performance
Ventilateurs-récupérateurs de chaleur et ventilateurs-récupérateurs
d’énergie — Méthode d’essai des performances
Reference number
ISO 16494:2014(E)
©
ISO 2014

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ISO 16494:2014(E)

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Published in Switzerland
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ISO 16494:2014(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 5
5 Airflow test . 6
5.1 General conditions . 6
5.2 Ducted heat recovery ventilators and energy recovery ventilators . 6
5.3 Unducted heat recovery ventilators and energy recovery ventilators . 9
6 Tracer gas tests. 9
6.1 General conditions . 9
6.2 Temperature conditions . 9
6.3 Preconditions . 9
6.4 Airflow conditions . 9
6.5 Unit operating voltage and frequency . 9
6.6 Tracer gas measurement methods . 9
7 Determination of efficiency .10
7.1 General conditions .10
7.2 Temperature and humidity conditions: inlets to ventilator .10
7.3 Preconditions .10
7.4 Airflow conditions .10
7.5 Static pressure conditions: ducted heat and energy recovery ventilators .11
7.6 Static pressure conditions: unducted heat and energy recovery ventilators .11
7.7 Unit operating voltage and frequency .11
7.8 Thermal performance measurement .11
8 Performance calculations .11
8.1 Performance calculations: ducted ventilators .11
8.2 Performance calculations: unducted ventilators .11
8.3 Unit Exhaust Air Transfer Ratio (UEATR) .11
8.4 Net supply airflow .12
8.5 Gross effectiveness .13
8.6 Coefficient of energy (COE) .14
8.7 Effective work (EW) .15
9 Test results .16
Annex A (normative) Airflow measurement method for both ducted and unducted ventilators .17
Annex B (normative) Decay method for measurement of net supply airflow .19
Annex C (normative) Unit exhaust air transfer ratio measurement methods .21
Annex D (normative) Thermal performance measurement .25
Annex E (informative) Example data collection and reporting sheets .28
Annex F (normative) Required instrument uncertainty .36
Annex G (informative) Construction of plenums for connection to inlets or outlets not
designed for connection of ductwork .37
Bibliography .38
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ISO 16494:2014(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 86, Refrigeration and air-conditioning,
Subcommittee SC 6, Testing and rating of air-conditioners and heat pumps.
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INTERNATIONAL STANDARD ISO 16494:2014(E)
Heat recovery ventilators and energy recovery
ventilators — Method of test for performance
1 Scope
This International Standard prescribes a method of testing the ventilation and energy related performance
of heat recovery ventilators (HRVs)and energy recovery ventilators (ERVs) that do not contain any
supplemental heating (except for defrost), cooling, humidification or dehumidification components.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3966:2008, Measurement of fluid flow in closed conduits — Velocity area method using Pitot static tubes
ISO 5167-1:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 1: General principles and requirements
ISO 5801:2007, Industrial fans — Performance testing using standardized airways
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
outdoor airflow
OA
volume of outside air entering the ventilator
Note 1 to entry: Indicated in Figure 1 as 1.
Note 2 to entry: Also referred to as ‘entering supply air’.
3.2
supply airflow
SA
outside air after passing through the ventilator
Note 1 to entry: Indicated in Figure 1 as 2.
Note 2 to entry: Also referred to as ‘leaving supply air’.
3.3
return (extract) airflow
RA
indoor air entering the ventilator
Note 1 to entry: Indicated in Figure 1 as 3.
Note 2 to entry: Also referred to as ‘entering exhaust air’.
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ISO 16494:2014(E)

3.4
exhaust airflow
EA
indoor air after passing through the ventilator
Note 1 to entry: Indicated in Figure 1 as 4.
Note 2 to entry: Also referred to as ‘leaving exhaust air’.
Key
1 outdoor airflow (OA) (entering)
2 supply airflow (SA) (leaving)
3 return airflow (RA) (entering)
4 exhaust airflow (EA) (leaving)
5 ventilator
6 indoor side
7 outdoor side
Figure 1 — Schematic numbering of airflows for heat and energy recovery ventilators
3.5
station
location in the test apparatus at which conditions such as temperature, humidity, pressure, or
airflow are measured
Note 1 to entry: These locations are identified as “station 1”, “station 2”, “station 3” and “station 4” for each of the
airflows indicated in Figure 1.
3.6
coefficient of energy
COE
total exchanged energy between the airstreams plus the power value of moving air, divided by the
power input
Note 1 to entry: The equation for determining the coefficient of energy is given in 8.6.
3.7
rating points
sets of supply and return airflows, static pressures at inlets and outlets, and speed control setting,
achieved during the airflow performance measurement, at which thermal performance tests (and
exhaust air transfer tests, if applicable) are performed
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ISO 16494:2014(E)

3.8
effective work
EW
total exchanged energy between the airstreams plus the power value of moving air minus the power input
Note 1 to entry: The equation for determining the effective work is given in 8.7.
Note 2 to entry: Effective work is expressed in W.
3.9
power value of moving air
rate of pressure energy and kinetic energy of the air delivered by the ventilator
Note 1 to entry: The equation that determines the power value of moving air is given in 8.6.1.
Note 2 to entry: Power value of moving air is expressed in J/s for P .
vma
3.10
gross effectiveness
measured effectiveness, not adjusted for leakage, motor heat gain, or heat transfer through the unit casing
Note 1 to entry: The sensible, latent or total gross effectiveness of an HRV or ERV, at equal airflows, is described in 8.5.
3.11
maximum rated airflow
the largest supply and return airflows, specified by the manufacturer, at which an airflow test is performed
Note 1 to entry: For ventilators with speed control devices, different maximum rated airflows may be defined for
each speed control setting at which the test is performed.
3.12
minimum rated airflow
the smallest supply and return airflows, specified by the manufacturer, at which an airflow test is performed
Note 1 to entry: For ventilators with speed control devices, different minimum rated airflows may be defined for
each speed control setting at which the test is performed.
3.13
net supply airflow
portion of the leaving supply airflow that originated as entering supply airflow
3
Note 1 to entry: The net supply airflow is represented by the variable Q , measured in m /s.
SANet
Note 2 to entry: The equations for determining net supply airflow are given in 8.4.1 (ducted units) and 8.4.2
(unducted units).
3.14
net supply airflow ratio
ratio determined by dividing net supply airflow by supply airflow
Note 1 to entry: Expressed as a percentage, and described in 8.4.1 and 8.4.2.
3.15
speed control device
device incorporated into the ventilator which controls the speed of the fan
3.16
standard air
3
dry air with a density of 1,2 kg/m
Note 1 to entry: These conditions approximate dry air at 20°C and 101,325 kPa absolute.
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ISO 16494:2014(E)

3.17
static pressure differential
absolute difference between inlet static pressure and outlet static pressure for each of the two airstreams
EXAMPLE Static pressures measured at │X -X │, or │X -X │.
2 1 4 3
3.18
thermal performance measurement
test procedure which measures the temperature and humidity of the supply air when a ventilator is
operating with the outside air and return air at specific psychrometric conditions
3.19
unit exhaust air transfer ratio
UEATR
tracer gas concentration difference between the supply airflow and the outdoor airflow divided by the tracer
gas concentration difference between the return airflow and the outdoor airflow, at a specified airflow
Note 1 to entry: The equation for UEATR is given in 8.3.
Note 2 to entry: UEATR is expressed as a percentage.
3.20
ventilator
self contained unit that includes fans to move air through the heat/energy exchanger
3.21
energy recovery ventilator
ERV
ventilator which is designed to transfer both heat and moisture between two isolated airstreams
3.22
fresh air mass flow rate
qm
2
leaving supply mass airflow rate at station 2
3.23
heat recovery ventilator
HRV
ventilator which is designed to transfer only heat between two isolated airstreams
3.24
unducted ventilator
heat recovery ventilator or energy recovery ventilator which is not intended for connection of ducts to any
of the airflow inlets or outlets except for model specific exterior termination systems as defined in 3.27
3.25
ducted ventilator
heat recovery ventilator or energy recovery ventilator which is intended for connection of ducts to one
or more of the airflow inlets or outlets and intended to address a range of static pressure differentials
from the duct(s)
3.26
duct
insulated or uninsulated closed passage for air that is installed as part of the ventilation system in
lengths determined by the needs of application, and is separate, prior to installation from exterior
terminations such as weather hoods
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ISO 16494:2014(E)

3.27
model-specific exterior termination system
weather hoods, fittings and through-wall penetrations designed by the ventilator manufacturer
specifically for installation with a specific model of ventilator, that comprise the complete passageway
connecting the ventilators outside air inlet and/or exhaust air outlet to the ventilator
3.28
net supply mass flow rate
qm
2,net
portion of the leaving supply mass airflow rate at station 2 that originated as entering supply mass flow
rate at station 1, accounting for UEATR
Note 1 to entry: Per the equation in 8.6.1and 8.6.2.
4 Symbols and abbreviated terms
Symbol Definition Units
C Initial tracer gas concentration in the test chamber (average of all measure-
i
ment points)
C Tracer gas concentration in outdoor air (OA)
o
C Tracer gas concentration at outdoor air inlet (station 1)
OA
C Specific heat at supply airflow kJ/kg K
p
C Tracer gas concentration at return air inlet (station 3)
RA
C Tracer gas concentration at supply air outlet (station 2)
SA
C Tracer gas concentration in the test chamber after t hours (average of all
t
measurement points)
h Enthalpy of the air at station 1 kJ/kg of dry air
1
h Enthalpy of the air at station 2 kJ/kg of dry air
2
qm Fresh air mass flow rate kg/s
2
qm Net supply mass flow rate kg/s
2,net
NSAR Net supply airflow ratio %
P Input power to any other electrical components in the ventilator W
aux
P Input power to all electric motors in the ventilator W
em
P
Input power to ventilator W
in
P Power value of moving air J/s
vma
3
Q Gross airflow m /s
3
Q Average of the three calculated overall airflow rates with the unit under m /s
1
test in operation as described in B.2.1.1 and B.2.1.2
3
Q Average of the three calculated natural airflow rates of the test chamber m /s
2
with the ventilator removed as described in B.2.2.1 and B.2.2.2
3
Q Airflow rate calculated using the data from a test ‘i’ as described in B.2.1.1, m /s
i
B.2.1.2, B.2.2.1 and B.2.2.2
3
Q Supply airflow m /s
SA
3
Q Net supply airflow m /s
SANet
ps External static pressures at the inlet(s) or outlet(s) Pa
n
t Length of time elapsed since the start of test unit operation s
T Temperature of the outdoor airflow at station 1 K
1
T Temperature of the supply airflow at station 2 K
2
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ISO 16494:2014(E)

Symbol Definition Units
UEATR Unit exhaust air transfer ratio %
3
V Air volume in the test chamber m
3
v Specific volume of the supply air m /kg
s
x Dry-bulb temperature (for sensible effectiveness); °C
or absolute humidity ratio (for latent effectiveness); kg water/kg dry air
or total enthalpy (for total effectiveness). J/kg
ε Effectiveness
5 Airflow test
5.1 General conditions
All tested equipment within the scope of this International Standard shall have the airflows determined
in accordance with the following provisions:
5.1.1 Temperature conditions
When measuring airflow, the laboratory ambient conditions shall be 20 ± 15 °C and 30 to 95 % RH.
Laboratory ambient temperature during the test shall be recorded and reported.
5.1.2 Speed control setting
The ventilator shall be tested using the manufacturer specified speed control settings. Speed control
settings shall not be adjusted during the test.
5.1.3 Unit operating voltage and frequency
The power supply voltage at the operating unit shall be within ± 2 % of the rated voltage. The power
supply frequency at the operating unit shall be within ± 1 % of the rated frequency.
5.2 Ducted heat recovery ventilators and energy recovery ventilators
5.2.1 Airflows measured
The gross airflow shall be measured and recorded at station 2 (Supply Airflow) and at station 3 (Return
Airflow) as shown in Figure 1, under the static pressure conditions indicated in 5.2.2.
5.2.2 Static pressure conditions
5.2.2.1 In order to properly characterize the performance of the unit, the ventilator shall be tested
at specified maximum rated and minimum rated airflows and at a minimum of three additional,
approximately evenly spaced intermediate airflows between the maximum rated airflow and minimum
rated airflow. This gives a minimum of five test points as shown in Figure 2. The airflow test points must
be reached by adjusting the test apparatus to change the static pressure differential. If the ventilator is
equipped with a speed control device, it shall not be adjusted during this test. Input power in watts shall
be measured and recorded at each test point.
5.2.2.2 Any inlet or outlet which is not designed for duct connection shall be maintained at an average
value of 0 ± 2,5 Pa, static pressure for all test points. However, if the ventilator is designed for installation
with model-specific exterior termination system as defined in 3.27, that system shall be installed.
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ISO 16494:2014(E)

Key
1 P-Q curve (supply airflow)
2 P-Q curve (return airflow)
3 minimum rated airflow
4 maximum rated airflow
Figure 2 — Representative chart of airflow performance
5.2.2.3 Static pressure measurement requirements
When testing for airflow, the requirements of 5.2.2.3 a) or 5.2.2.3 b) shall apply.
a) Only for units tested in a ducted setup:
1) For the maximum and minimum rated airflows the absolute value of static pressure at inlet
(ps ) and outlet (ps ) shall be equal within 10 Pa or 5 %, whichever is greater, of the larger of
1 2
the measured values of ps or ps , except as noted in 5.2.2.2.
1 2
2) The absolute value of static pressure at inlet (ps ) and outlet (ps ) shall be equal, within 10 Pa
3 4
or 5 %, whichever is greater, of the larger of the measured values of ps and ps , except as
3 4
noted in 5.2.2.2.
3) For each intermediate test point, the absolute value of static pressures at each inlet and outlet
(ps , ps , ps and ps ) shall be equal within 10 Pa or 5 %, whichever is greater, of the largest of
1 2 3 4
the measured value of ps , ps , ps or ps , except as noted in 5.2.2.2.
1 2 3 4
b) Only for units tested in a two room setup:
1) For all tests the value of static pressure at inlet (ps ) and inlet (ps ) shall be ≤ 0 Pa, and (ps )
1 3 1
and (ps ) shall be equal within 10 Pa, or 5 %, whichever is greater, of the larger of the measured
3
values of ps or ps .
1 3
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ISO 16494:2014(E)

2) The value of static pressure at the outlets (ps ) and (ps ) shall be equal, within 10 Pa, or 5 %,
2 4
whichever is greater, of the larger measured value of ps or ps , except as noted in 5.2.2.2.
2 4
Key
1 P-Q curves
2 minimum rated airflows
3 maximum rated airflows
NOTE Each of the individual P-Q curves shown here is generated at a different speed control setting. In this
example, the ventilator either has just five discrete speed control settings, or has a continuously-variable speed
control. See 5.2.2.4. For simplification, in this example only the supply air P-Q curves are shown.
Figure 3 — Representative chart of multispeed/variable speed ventilator airflow performance
5.2.2.4 For units with speed controls, additional airflow tests must be performed at the alternate speed
settings. If the speed control device setting is infinitely variable, the test as described in 5.2.2.1 shall be
performed separately at a minimum of five speed control settings, including the highest and lowest speed
control setting and a minimum of three additional approximately evenly spaced speed control settings
between the highest and lowest settings.
5.2.2.5 If supply and return airflows cannot be measured simultaneously, static pressures at all four
stations at the time of measurement of the second airflow must be equal within ± 10 Pa, or 5 % of the larger
of the measured static pressures, whichever is greater, to the static pressures at the time of measurement
of the first airflow.
5.2.3 Airflow measurement methods for ducted heat recovery and energy recovery ventilators
Airflow measurement methods are given in Annex A.
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ISO 16494:2014(E)

5.3 Unducted heat recovery ventilators and energy recovery ventilators
5.3.1 Airflows measured
The net supply airflow shall be determined. Input power, in watts, shall be measured and recorded.
5.3.2 Static pressure conditions
The effective/net airflow shall be determined with the static pressures at all inlets and outlets equal
within ± 2,5 Pa.
5.3.3 Airflow measurement methods for unducted heat recovery and energy recovery ventilators
Net supply airflow measurement methods are given in Annex B for the decay method. Alternately, the
net supply airflow for unducted ventilators may be measured at points 2 and 3, by the methods given
in Annex A and Annex C, and the Formula in 8.4.1 provided that appropriate plenums are constructed
around the inlets and outlets as indicated in Annex G. If the ventilator is designed for installation with
model-specific exterior termination systems as defined in 3.18, that system shall be installed.
6 Tracer gas tests
6.1 General conditions
All heat recovery ventilators and energy recovery ventilators within the scope of this International
Standard shall have the unit exhaust air transfer rate and the net supply airflow rate or net supply airflow
volume determined in accordance with the provisions of this clause of this International Standard.
Tracer gas tests at other airflows and static pressure regimes may also be performed.
6.2 Temperature conditions
During tracer gas tests the laboratory ambient conditions shall be 20 ±15 °C and 30 to 95 % RH.
6.3 Preconditions
Airstreams shall be held at lab ambient temperature and humidity conditions and must remain stable
for the duration of the tracer gas test. Test(s) shall be performed until tracer gas levels have stabilized.
6.4 Airflow conditions
Tracer gas testing shall be performed at the same static pressures, and at the same speed control setting
used for the thermal performance measurement as required by sections 5.2.2.2, 5.2.2.3 and 5.2.2.4 in
accordance with the setup type (ducted or two-room) chosen for the tracer gas testing.
6.5 Unit operating voltage and frequency
The power supply voltage at the operating unit shall be within ± 2 % of the rated voltage. The power
supply frequency at the operating unit shall be within ± 1 % of the rated frequency.
6.6 Tracer gas measurement methods
Tracer gas measurement methods are given in Annex B or Annex C.
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ISO 16494:2014(E)

7 Determination of efficiency
7.1 General conditions
All equipment within the scope of this International Standard shall have the gross effectiveness, the
coefficient of energy and the effective work determined in accordance with the provisions of this
International Standard and rated at one or more of the heating and/or cooling conditions specified in
Table 1 and/or Table 2.
7.2 Temperature and humidity conditions: inlets to ventilator
Tests at cooling conditions shall be carried out under the conditions given in one or more of the columns
T1 through T4 in Table 1. Tests at heating conditions shall be carried out under the conditions given in
one or more of the columns T5 through T7 in Table 2.
Table 1 — Conditions of t
...