RA3.7 contains procedures for measuring the airflow in mechanical ventilation systems to confirm compliance with the requirements of ASHRAE 62.2.
RA3.7 is applicable to mechanical ventilation systems in residential dwelling units.
RA3.7 provides required procedures for installers, HERS raters and others who are required to perform field verification of mechanical ventilation systems for compliance with Part 6.
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Diagnostic |
Description |
Procedure |
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Whole-Building Mechanical Ventilation Airflow – Continuous Operation |
Verify that whole-building ventilation system complies with the airflow rate required by ASHRAE Standard 62.2. |
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Whole-Building Mechanical Ventilation Airflow – Intermittent Operation |
Verify that whole-building ventilation system complies with the airflow rate required by ASHRAE Standard 62.2. |
The instrumentation for the air distribution diagnostic measurements shall conform to the following specifications:
RA3.7.2.1 Pressure Measurements
All pressure measurements shall be measured with measurement systems (i.e., sensor plus data acquisition system) having an accuracy equal to or better than ± 1% of pressure reading or ± 0.2 Pa (0.0008 inches water) (whichever is greater). All pressure measurements within the duct system shall be made with static pressure probes such as Dwyer A303 or equivalent.
RA3.7.2.2 Airflow Rate Measurements
All measurements of ventilation fan airflow rate shall be made with an airflow rate measurement apparatus (i.e., sensor plus data acquisition system) having an accuracy equal to or better than ± 10% of reading. The apparatus shall have an accuracy specification that is applicable to the airflow rates that must be verified utilizing the procedures in Section RA3.7.4.
RA3.7.2.3 Calibration
All instrumentation used for mechanical ventilation system airflow rate diagnostic measurements shall be calibrated according to the manufacturer’s calibration procedure to ensure the airflow measurement apparatus conforms to the accuracy requirement specified in Section RA3.7.2.2.
Ventilation system airflow rate shall be measured using one of the apparatuses 'listed in Section RA3.7.3. The apparatus shall produce airflow rate measurements that conform to the accuracy requirements specified in Section RA3.7.2 for measurements of residential mechanical ventilation system airflow at system inlet or outlet terminals, grilles or registers for single or multiple branch ventilation duct systems.
The airflow rate measurement apparatus manufacturers shall publish in their product documentation, specifications for how their airflow measurement apparatuses are to be used for accurately measuring residential mechanical ventilation system airflow at system inlet or outlet terminals, grilles or registers of single or multiple branch ventilation systems.
The airflow measurement apparatus manufacturers shall certify to the Energy Commission that use of the apparatus in accordance with the specifications given in the manufacturer's product documentation will produce measurement results that are within the accuracy required by Section RA3.7.2.2.
For the airflow measurement apparatuses that are certified to the Commission as meeting the accuracy required by Section RA3.7.2.2, the following information shall be posted on the Energy Commission website, making the information available to all people involved in the airflow verification compliance process:
(a) The product manufacturers' model numbers for the airflow measurement apparatuses.
(b) The product manufacturers' product documentation that gives the specifications for use of the airflow measurement apparatuses to accurately measure residential mechanical ventilation system airflow at system inlet or outlet terminals, grilles or registers of single or multiple branch ventilation systems.
A manufacturer's certification to the Commission of the accuracy of the airflow measurement apparatus, and submittal to the Commission of the product documentation that specifies the proper use of the airflow measurement apparatus to produce accurate airflow rate measurements shall be prerequisites for allowing the manufacturer's airflow measurement apparatus to be used for conducting the system airflow verification procedures in Section RA3.7 for demonstrating compliance with Part 6.
RA3.7.3.1 Residential Mechanical Exhaust Airflow Measurement Device
A flowmeter designed for measurement of residential exhaust airflows that meets the applicable instrument accuracy specifications in RA3.7.2 may be used to measure the mechanical exhaust ventilation airflow.
A powered and pressure balanced flow capture hood (subsequently referred to as a Powered Flow Hood) that has the capability to balance the flow capture static pressure difference between the room and the flow capture hood enclosure to 0.0 ± 0.2 Pa (0.0008 inches water) and meets the applicable instrumentation specifications in Section RA3.7.2 may be used to verify the ventilation airflow rate if the powered flow hood has a flow capture area at least as large as the ventilation system inlet or outlet terminal, register, or grille in all dimensions. The fan adjustment needed to balance the flow capture static pressure difference between the room and the flow capture hood enclosure to 0.0 ± 0.2 Pa (0.0008 inches water) shall be provided by either an automatic control or a manual control operated in accordance with the apparatus manufacturer's instructions specified in the manufacturer's product documentation.
A traditional flow capture hood meeting the applicable instrumentation specifications in Section RA3.7.2 may be used to verify the ventilation system airflow rate if the non-powered flow hood has a capture area at least as large as the ventilation system inlet or outlet terminal, register, or grille in all dimensions.
This section describes the procedures used to verify Mechanical ventilation system airflow.
RA3.7.4.1 Mechanical Ventilation Airflow Rate Measurement - Continuous Operation
If multiple fans are specified to operate simultaneously to provide the total required ventilation airflow, the measurements shall be made with all applicable fans operating simultaneously.
a) A flow measuring device that meets the applicable instrumentation requirements given in Section RA3.7.2, and RA3.7.3 shall be used to measure the ventilation airflow(s).
b) Measure and record the ventilation airflow(s).
c) If the measured total airflow is greater than or equal to the ventilation airflow rate required by the Standards or the Certificate of Compliance, the mechanical ventilation system complies. Otherwise the mechanical ventilation system does not comply, and corrective action shall be taken.
a) A flow measuring device that meets the applicable instrumentation requirements given in Section RA3.7.2, and RA3.7.3 shall be used to measure the ventilation airflows.
b) Confirm that both the supply side and the exhaust side of the balanced system operate simultaneously in response to a shared system control.
c) Measure the airflow rate for the exhaust side of the system.
d) Measure the airflow rate for the supply side of the system.
e) Calculate the percent difference between the exhaust and supply airflow rates.
f) Calculate the average of the exhaust and the supply airflow rates.
g) If the exhaust and supply airflow rates are within 20% of each other, and the average of the exhaust and supply airflow rates is greater than or equal to the airflow rate required by the Standards or the Certificate of Compliance, the balanced ventilation system complies. Otherwise, the system does not comply, and corrective action shall be taken.
RA3.7.4.2 Mechanical Ventilation Airflow Rate Measurement - Intermittent Operation
The Executive Director may approve intermittent mechanical ventilation systems, devices, or controls for use for compliance with field verification and diagnostic testing requirements for mechanical ventilation airflow, subject to a manufacturer providing sufficient evidence to the Executive Director that the installed mechanical ventilation systems, devices, or controls will provide at least the minimum ventilation airflow required by the Standards, and subject to consideration of the manufacturer's proposed field verification and diagnostic test protocol for the ventilation system(s).
Approved systems, devices, or controls, and field verification and diagnostic test protocols for intermittent mechanical ventilation systems shall be listed in directories published by the Energy Commission.
RA3.7.4.3 Kitchen Range Hood Verification
The verification shall utilize certified rating data from the Home Ventilating Institute (HVI) Certified Home Ventilating Products Directory at https://hvi.org/proddirectory/index.cfm or another directory of certified product performance ratings approved by the Energy Commission for determining compliance. The verification procedure shall consist of visual inspection of the installed kitchen range hood to verify and record the following information:
(a) The manufacturer name and model number.
(b) The model is listed in the HVI Directory.
(c) The rated airflow value listed in the HVI directory.
(d) The sound rating value listed in the HVI directory.
(e) If the value for the rated airflow given in the directory is greater than or equal to the airflow requirements specified in the Standards, and if the value for the sone rating given in the directory is less than or equal to the sone rating requirements specified in Standards, then the kitchen range hood complies, otherwise the kitchen range hood does not comply.