Under Title 24, a new home's HVAC system must meet specific duct sealing requirements. What is the maximum allowable duct leakage rate for new construction?
Correct Answer
B) 6% of fan flow
Title 24 requires duct systems in new construction to have leakage rates not exceeding 6% of fan flow when tested at 25 Pascals, ensuring energy efficiency.
Why This Is the Correct Answer
Title 24 Part 6 (California Energy Code) sets the maximum allowable duct leakage at 6% of fan flow when tested at 25 Pascals for new construction. This threshold balances practical installation tolerances with meaningful energy savings — tighter duct systems reduce conditioned-air losses that inflate heating and cooling bills.
Why the Other Options Are Wrong
Option A: 10% of fan flow
10% of fan flow is too lenient and does not meet Title 24 new-construction standards. It may be confused with older or less stringent standards, but California's energy code demands tighter sealing to meet its aggressive efficiency goals.
Option C: 12% of fan flow
12% of fan flow far exceeds the allowable limit. Leakage at this level would represent a significant energy waste and would fail a Title 24 duct leakage test, triggering mandatory remediation before a certificate of occupancy is issued.
Option D: 8% of fan flow
8% of fan flow is closer to the correct answer but still exceeds the 6% maximum. Candidates who recall a number near 6% but are unsure of the exact figure sometimes guess 8%, making this a common distractor.
Memory Technique
Think '6 for new' — a brand-new duct system should be nearly airtight, and 6% is the strictest common threshold. Picture a brand-new sealed envelope: only 6 out of 100 letters leak out.
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