Duct Leakage Testing Flashcards
7 cards from real HERS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Duct Leakage Testing flashcards as text
In the HERS Rating Index, how does duct leakage to outside affect the final HERS score?
Answer: Higher Qto increases the HERS score, indicating lower energy efficiency
Greater duct leakage to outside increases energy losses, which raises the HERS score (worse efficiency), moving the home further from the reference 100-point score.
What minimum size opening is required in the duct system to connect a Duct Blaster fan during testing?
Answer: The fan can connect through any opening at least as large as its collar diameter
The Duct Blaster fan collar must have an opening at least as large as its diameter; a return register, filter slot, or plenum cutout are common connection points.
A duct system with 250 CFM25 of total leakage and 80 CFM25 of outside leakage has what percentage of its total leakage going to the outside?
Answer: 32%
80 ÷ 250 × 100 = 32%, meaning 32% of total duct leakage is exchanged with unconditioned space.
Which duct component is a frequent source of large leakage found during HERS testing?
Answer: Register boots and plenum connections
Register boots and plenum connections are among the most common large leakage sites because they involve transitions and are often installed with gaps or missing sealant.
If a Duct Blaster shows 0 CFM at 25 Pascals, what does this result indicate?
Answer: The duct system is essentially airtight with no measurable leakage
A reading of 0 CFM25 indicates a perfectly sealed duct system with no measurable leakage pathways at the test pressure.
During a Qto test using the pressure-matching method, what pressure is the house envelope brought to?
Answer: The same pressure as the duct system (typically 25 Pa)
In pressure matching, a blower door brings the house to the same pressure as the duct system so that no net airflow exists between house and ducts, isolating only leakage to outside.
Which of the following BEST describes 'duct leakage exemption' provisions sometimes allowed in energy codes?
Answer: Ducts in conditioned space may be exempt from Qto testing
Many energy codes and rating programs allow an exemption from Qto testing when all ducts and air handlers are verified to be within the conditioned thermal envelope.