Right Sizing Your Returns

Emily Beierle October 4, 2019

Our database updates are complete, and you may now upload jobs that have new measures or are utilizing the adaptability between shell/HVAC for certain measures. Look for an updated Job Submission Webinar in the next two weeks, as well as updated Installation Specifications.

This month, we’d like to take a deeper diver into one of our new measures: Right-Size Return Duct(s) and Filter/Grille.

Claiming the measure and installation specifications:

When claiming the ‘Right-Size Return Duct’ upgrade measure, best practice is to use Wrightsoft or similar ACCA Manuals J/D/S/T software to demonstrate appropriate duct sizing for the system. If you don’t currently use ACCA-based software, there are some additional resources that may be used to support the right-size duct return measure claim. There are numerous apps available for mobile phones and tablets, and some are free. Below are some additional resources you may find helpful.

Online calculator/Ductulators

For Flex Ducts: https://www.oceanhvac.com/ductulator/

For Sheetmetal Ducts: https://ductcalc.ca/

When submitting an incentive application with the ‘Right-Size Return’ measure, make sure to provide the Pre-Install/Existing return duct size/diameter and Post-Install/Improved return duct size/diameter on your Scope of Work so that Desktop QA Review can compare them. Photos of the existing (pre-installation) return duct, size, and filter grille are required with this measure.

All ‘Right-Size Return’ Ductulator calculations should use a Friction Rate of 0.03 as the upgrade target. Please note that these online and downloadable application-based Ductulators are third-party products that are not developed or maintained by Build It Green, Franklin Energy, or PG&E, so reliance on and/or use of their calculations for installation work is the sole responsibility of the participating contractor. It is a best practice to double-check these calculations against ACCA Manuals J/D/S/T prior to commencing installation work and/or purchase of materials for installation.

Work-Scope Description Example:

‘Existing 12″ diameter R-4 return flex duct upgraded to 18″ diameter R-8 return flex duct, per Ductulator calcs with Friction Rate 0.03, Duct TEL 100 ft., System Design Airflow 800 CFM’.

For QA review verification purposes, if you’re not submitting an ACCA-based software report, you may provide a screenshot using the Ductulator tool that you chose to support the description you provided of your Post-Install upgrades.

Ductulator Screenshot Example:

The filter grille and filter media sizes should also be described in the Work-Scope documentation, so they can be compared by QA review staff, Pre- and Post-Installation.

Work-Scope Description Example:

‘Existing 12x24x1 stamped face filter grill and 12x24x1 MERV 8 filter upgraded to 20x25x5 bar type filter grille and 20x25x5 MERV 8 filter, rated for 0.05 IWC pressure drop at 800 CRM’.

Please note that beginning January 1, 2020, the air filter requirement increases to MERV 13 minimum, with an allowance of 0.1 IWC pressure drop at system design airflow (see 2019 Title-024, Part 6 – Residential Compliance Manual for more details). Below is an example of the kind of Title-24 required labeling to look for on filter media and reference on Work-Scope documentation.

Typical Filter Label Example:

Participating contractors are strongly encouraged to use ACCA J/D/S/T software to determine appropriate duct and filter-grille type/sizing for upgraded duct systems in order to achieve greater system performance. Use of this software in system design is a fundamental component of High Performance HVAC Installation (HPHI) training and delivery.

About the Author

Emily Beierle

Emily Beierle-O'Brien is a Program Management Associate at Build It Green and works closely with the Home Upgrade Program to ensure quality and accuracy within the program implementation. She is passionate about green building and sustainable living.

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