Practice Test Geeks(HERS) Certified Home Energy Rating System Rater Practice Test
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Blower Door & Duct 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 Blower Door & Duct Testing flashcards as text

  1. A rater suspects that wind is affecting blower door readings. Which technique helps compensate for wind-induced pressure fluctuations?

    Answer: Take multiple fan pressure readings and average them

    Averaging multiple readings or using a data-logging manometer to record many samples over time compensates for short-term wind pressure fluctuations.

  2. Which metric best represents the air tightness of a home independent of its volume?

    Answer: ACH50

    ACH50 (air changes per hour at 50 Pa) normalizes CFM50 by home volume, allowing meaningful comparisons between homes of different sizes.

  3. During a duct blaster test, the technician notices pressure in the duct system won't reach 25 Pa even at maximum fan speed. What is the most likely cause?

    Answer: There is a large unsealed duct opening or disconnected duct section

    If the duct blaster cannot reach 25 Pa, it usually means there is an extremely large leak—such as a disconnected duct section or an unsealed chase—allowing air to escape faster than the fan can pressurize the system.

  4. What is the formula for converting CFM50 to ACH50?

    Answer: ACH50 = CFM50 × 60 / conditioned volume (ft³)

    ACH50 = (CFM50 × 60 min/hr) ÷ conditioned volume in cubic feet, converting the per-minute flow to an hourly air change rate.

  5. In a duct leakage test, what does a very low CFM25 out reading (near zero) with a relatively high CFM25 total reading suggest?

    Answer: The duct system has significant leaks, all within the conditioned space

    High total leakage with near-zero outside leakage means ducts are leaking significantly but all the leakage goes into conditioned space, not to unconditioned areas.

  6. Which RESNET-recognized testing method allows duct leakage to be measured without pressurizing or depressurizing the entire duct system?

    Answer: Delta Q method

    The Delta Q method estimates duct leakage to outside by comparing house pressure with the air handler running versus off, without using a duct blaster.

  7. A blower door test is performed on a home with a conditioned floor area of 2,500 ft² and 8 ft ceilings. CFM50 = 1,200. What is the ACH50?

    Answer: 3.6 ACH50

    Volume = 2,500 × 8 = 20,000 ft³; ACH50 = (1,200 × 60) / 20,000 = 72,000 / 20,000 = 3.6 ACH50.