BLOG Top Tips for Preparing Your Home for a H.E.R.S. Rating Duct Leakage Test May 12, 2025

A H.E.R.S. (Home Energy Rating System) duct leakage test is a critical step in ensuring your home’s heating and cooling system is operating efficiently and meeting California energy‐code requirements. By minimizing air leaks in your ductwork, you’ll not only improve indoor comfort but also reduce energy bills. Follow these top tips to get your home ready, streamline the testing process, and maximize your score.

1. Understand What the Test Involves

Before the technician arrives, familiarize yourself with the process:

A blower fan is attached to your duct system to pressurize it.

All registers and grilles are covered or sealed.

The technician measures how much air escapes, expressed in cubic feet per minute (CFM) at a 25 Pa pressure.

Knowing what to expect will help you prepare and ask informed questions.

2. Clear Access to All Registers and Grilles

Technicians need unobstructed access to both supply and return vents throughout your home:

Move furniture, rugs, or décor at least 2 feet away from each vent.

Remove floor mats and area rugs if they cover returns.

Ensure closets or storage rooms with vents are unlocked and cleared.

3. Remove or Replace Air Filters

Dirty or restrictive filters can skew test results and prolong the process:

Remove all HVAC filters and set aside in a clean bag.

If you haven’t replaced your filter in over three months, have a fresh filter on hand—technicians often reinstall a clean one after testing.

4. Seal Obvious Gaps and Tears

While a professional will identify leaks, pre‐sealing easy spots can improve your score:

Use foil HVAC tape on visible seams and joints.

Apply mastic sealant around boot penetrations and register collars.

Check access doors on air handlers and seal with weatherstripping if loose.

5. Prepare Your Attic and Crawlspace

Many ducts run through attics or crawlspaces, where leaks are common:

Ensure the technician can safely reach access hatches—clear away insulation or debris.

If you have loose-fill insulation, brush it back at least a foot from duct seams so leaks are easier to spot.

Turn on attic lighting so the rater can illuminate dark areas.

6. Turn Off Zone Dampers and Smart Controls

To get accurate baseline measurements:

Fully open any manual or motorized zone dampers.

Temporarily disable zoning controls or programmable thermostats that might shut off the system during testing.

Keep the thermostat set to “fan on” mode if possible.

7. Schedule During Moderate Weather

Extreme heat or cold can force the HVAC system to cycle on/off, complicating the test:

Aim for a mild day (ideally 60–75 °F outside).

Avoid scheduling right before or after you’ve run the system continuously.

8. Document Your Preparations

A quick pre‐test checklist helps both you and the rater track readiness:

All vents cleared ✔

Filters removed ✔

Preliminary sealant applied ✔

Attic/crawlspace access cleared ✔

Dampers open & controls set ✔

Photograph or note any remaining concerns so you can discuss them afterward.

9. Ask About Post‐Test Repairs

Once you’ve seen the leakage results, you’ll likely want to fix any detected issues:

Inquire whether your H.E.R.S. rater offers duct sealing services or referrals.

Get quotes for more extensive repairs (e.g., duct replacement or insulation upgrades).

Discuss cost‐effective options like spray‐foam sealing or professional mastic application.

10. Maintain Good Duct Health Year-Round

Passing the test is great—but long‐term efficiency requires ongoing care:

Replace filters every 3 months.

Keep vents and returns unobstructed.

Inspect attic and crawlspace ducts annually for new gaps or settling insulation.

Ready to Get Started?

At A H.E.R.S. Rater, Inc., we specialize in fast, accurate duct leakage testing and expert energy‐efficiency guidance across California’s Central Valley and Newport Beach. Contact us today to schedule your H.E.R.S. duct leakage test and ensure your home is as energy‐smart as it can be.