HVAC System Evaluation 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 HVAC System Evaluation flashcards as text
Under HERS Rating rules, what is the Reference Home HVAC system assumption for a home with no mechanical cooling in a cooling-dominated climate?
Answer: The Reference Home assumes a standard central AC system regardless of the rated home
Per RESNET standards, the Reference Home always includes a code-minimum central air conditioning system in applicable climates, even if the rated home has none.
A HERS rater documents that an air handler is located in an unconditioned attic with R-8 duct insulation. What HERS penalty applies compared to ducts inside conditioned space?
Answer: Increased duct conduction losses are modeled, raising the HERS Index
Ducts in unconditioned attics incur thermal conduction losses that are modeled in the HERS simulation, increasing energy use and the HERS Index compared to ducts in conditioned space.
Which tool is used to measure airflow through individual supply registers during HVAC commissioning for a HERS rating?
Answer: Flow hood (capture hood)
A flow hood (capture hood or balancing hood) is placed over individual registers to directly measure the airflow in CFM at each supply or return grille.
A newly constructed home has an AFUE 96% condensing gas furnace. What efficiency advantage does a condensing furnace have over a non-condensing unit?
Answer: It extracts additional heat from flue gases by condensing water vapor before exhausting them
Condensing furnaces extract latent heat by cooling exhaust gases enough to condense water vapor, recovering energy that would otherwise be lost up the flue.
When evaluating a zoned HVAC system for a HERS rating, what is the primary modeling concern with bypass dampers?
Answer: Bypass dampers can cause excessive static pressure and reduce system airflow efficiency
Bypass dampers divert excess airflow when zones close, which can increase system static pressure and cause inefficient operation, coil freeze-up, or reduced equipment life.
In HERS rating software, which input primarily determines the modeled sensible heat ratio (SHR) of a cooling coil?
Answer: Equipment rated capacity and local design humidity conditions
The modeled SHR is determined by the equipment's rated performance and local design conditions (temperature and humidity) used in the HERS simulation.
A HERS rater finds that an energy recovery ventilator (ERV) is installed but ducted directly into the return plenum without a dedicated outdoor air connection. What is the problem?
Answer: Without a dedicated outdoor air intake, the ERV cannot provide proper fresh air ventilation
An ERV requires a dedicated outdoor air intake to transfer fresh outdoor air into the home; without it, the unit cannot provide the ventilation it is designed for.