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
What is the purpose of the pressure pan test in duct diagnostics?
Answer: To locate which registers have the greatest duct leakage to outside
A pressure pan placed over each register measures the pressure difference behind it, identifying registers associated with ducts that leak outside the conditioned space.
During a blower door test, which measurement channel on the manometer typically reads building pressure with respect to outside?
Answer: The differential channel (B-A or A-B)
The differential channel measures the pressure difference between inside and outside (or across the blower door fan), which is the key value for calculating air leakage.
A rater finds that CFM25 out (duct leakage to outside) exceeds the RESNET threshold for the home size. What is the most appropriate next step?
Answer: Report the result and recommend duct sealing, then retest
When duct leakage exceeds thresholds, the rater reports the finding, recommends corrective duct sealing by the contractor, and then conducts a retest to verify compliance.
What term describes duct leakage that exits into an unconditioned space such as an attic or crawlspace?
Answer: Duct leakage to outside
Duct leakage that goes into unconditioned spaces (attic, crawlspace, garage) is called duct leakage to outside because it effectively leaves the conditioned envelope.
Which instrument is used to simultaneously measure fan flow and building pressure difference during a blower door test?
Answer: Digital manometer connected to the blower door fan and building
A digital manometer measures both the pressure difference across the building envelope and the flow through the blower door fan, allowing CFM50 to be calculated.
For HERS rating purposes, what does 'verified duct leakage' mean when ducts are entirely inside conditioned space?
Answer: The rater may use a default duct leakage value without testing
When all ducts are confirmed to be within the conditioned envelope, RESNET allows raters to use a default duct leakage assumption rather than requiring a measured test.
What is the typical baseline depressurization target for a blower door test per ASTM E779?
Answer: 50 Pa
ASTM E779 and RESNET protocols specify 50 Pascals as the reference depressurization pressure, which is why results are expressed as CFM50.