CSLB C-20 HVAC ContractorVentilation and Air DistributionMedium
Per California Title 24 requirements for a newly installed residential duct system, what is the maximum allowable total duct leakage as verified by a HERS rater's diagnostic test?
- A15% of total fan airflow
- B2% of total fan airflow
- C5% of total fan airflow
- D25% of total fan airflow
Show answer & explanationAnswer & explanation
Correct answer: C. 5% of total fan airflow
Title 24 requires new duct systems to be tested and verified with total leakage not exceeding 5% of the air handler's design airflow, ensuring energy efficiency and proper delivered CFM to conditioned spaces.
Why the other options are wrong
- A. 15% is closer to the threshold sometimes used for duct alterations, not new systems.
- B. 2% is stricter than the actual code threshold for new systems.
- D. 25% far exceeds any Title 24 leakage compliance limit.
Title 24 Duct Leakage Testing
California energy code requirement mandating diagnostic testing of new duct systems to confirm leakage does not exceed 5% of total fan airflow.
- HERS rater performs required verification
- Applies to new construction duct systems
- Duct sealing with mastic or UL-181 tape ensures compliance
Memory trick: Five percent or less keeps Title 24 happy.