Diagnostics & Performance 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 Diagnostics & Performance Testing flashcards as text
During a duct leakage test, the technician measures a Qn (duct leakage to outside) of 0.12. What does this indicate?
Answer: Duct leakage exceeds typical Energy Star thresholds
A Qn of 0.12 (12% of system airflow) is well above typical Energy Star thresholds of 0.06 or 6%, indicating excessive duct leakage.
What instrument is used to measure airflow at individual supply and return registers during a HERS field verification?
Answer: Flow hood (balometer)
A flow hood (balometer) is placed over a register to directly measure the airflow volume in CFM at each supply or return grille.
A house tests at 4.2 ACH50 on the blower door. If the HERS Index target requires ≤3.0 ACH50, what is the next appropriate step?
Answer: Identify and air seal leakage sites, then retest
The rater must locate air leakage pathways using smoke sticks or infrared imaging, perform air sealing, and retest to confirm compliance.
Which of the following best describes the purpose of a pressure pan test?
Answer: Identifies which duct branches are leaking by pressurizing individual registers
A pressure pan (blocking pan) placed over a register and connected to a manometer identifies leaky duct sections by showing elevated pressure relative to the house.
When testing for combustion safety, a technician measures a Carbon Monoxide (CO) concentration of 35 ppm in the appliance flue gas. What action is required?
Answer: Immediately shut down the appliance and notify the owner
A CO reading of 35 ppm in the flue is dangerously elevated; the appliance must be shut down and the owner notified before continuing the inspection.
What does the term 'total duct leakage' (Qtotal) represent in duct blaster testing?
Answer: All air leaking from the duct system into both conditioned and unconditioned spaces
Qtotal measures all air escaping the duct system regardless of destination — into conditioned space, unconditioned space, or outside.
A HERS rater performing a mechanical ventilation verification discovers the measured exhaust flow is 45 CFM but the design calls for 60 CFM. What is the correct finding?
Answer: Fail, because the measured flow does not meet the designed ventilation rate
HERS field verification requires that measured mechanical ventilation airflow meet or exceed the design rate; 45 CFM versus a 60 CFM design is a failing condition.