Heating, Ventilation & Air Conditioning (HVAC) Flashcards
7 cards from real BPI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Heating, Ventilation & Air Conditioning (HVAC) flashcards as text
What is the purpose of measuring CO in the undiluted flue gas (not ambient air) during a combustion analysis?
Answer: To assess burner performance and identify combustion problems before dilution air masks them
Measuring CO in undiluted flue gas directly reveals combustion quality at the burner; dilution air in the flue would mask high CO readings if measured downstream.
Which condition would cause a heat pump to operate in emergency heat (auxiliary) mode more frequently than expected?
Answer: Low outdoor temperatures causing the heat pump to lose capacity
Heat pumps lose heating capacity as outdoor temperature drops; when capacity falls below the building's heating load, auxiliary (emergency) heat activates to compensate.
In a forced-air system, what does high return static pressure typically indicate?
Answer: Restricted return air path — undersized returns, dirty filter, or blocked grilles
High return static pressure means the air handler is working harder than designed to pull air back from the space, typically caused by undersized returns, a clogged filter, or blocked grilles.
What is the difference between sensible heat and latent heat in HVAC applications?
Answer: Sensible heat changes temperature; latent heat changes moisture content without temperature change
Sensible heat causes a measurable temperature change, while latent heat is the energy involved in changing water's phase (evaporation/condensation) without a temperature change.
A BPI analyst suspects a gas furnace has a cracked heat exchanger. Which field test provides the most direct evidence?
Answer: Measuring CO in the supply air stream while the furnace fan runs with the burner on
CO detected in supply air while the burner is firing indicates combustion gases are crossing through a crack in the heat exchanger into the air stream.
What does the Seasonal Energy Efficiency Ratio (SEER) represent for air conditioning equipment?
Answer: Total seasonal cooling output in BTU divided by total seasonal electricity input in watt-hours
SEER is a seasonal metric calculated as total BTUs of cooling divided by total watt-hours of electricity consumed over a typical cooling season, reflecting real-world usage across varying conditions.
When installing a supply air register in a bedroom, BPI recommends transfer pathways to ensure which outcome?
Answer: Return air can flow from closed bedrooms back to the central air handler
Without transfer pathways (jump ducts, door undercuts, transfer grilles), closing bedroom doors pressurizes those rooms and starves the return system, increasing duct leakage problems.