Refrigerant Transition and Retrofit Considerations Flashcards
7 cards from real ESCO A2L practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Refrigerant Transition and Retrofit Considerations flashcards as text
When transitioning from R-410A to R-454B, which system component most commonly requires adjustment or replacement?
Answer: The expansion device (TXV or EEV)
The thermostatic expansion valve (TXV) or electronic expansion valve (EEV) often requires adjustment or replacement because R-454B has different thermodynamic properties and pressure-enthalpy characteristics than R-410A.
Which A2L refrigerant is a single-component (pure) refrigerant increasingly used in new residential split systems as a lower-GWP alternative to R-410A?
Answer: R-32
R-32 is a pure, single-component A2L refrigerant used globally in new residential HVAC equipment as a lower-GWP alternative to R-410A, with the benefit of no fractionation during leaks or partial recoveries.
What is the approximate GWP of R-454B compared to R-410A's GWP of approximately 2,088?
Answer: GWP of approximately 467
R-454B has a GWP of approximately 467, representing roughly a 78% reduction compared to R-410A's GWP of about 2,088, making it a primary candidate under the AIM Act HFC phasedown schedule.
When is it ever permissible to mix an A2L refrigerant with a remaining R-410A charge in a system?
Answer: It is never permissible to mix different refrigerant types
Mixing different refrigerant types is never permissible because it creates a contaminated mixture with unknown properties that cannot be legally reclaimed or reused, per EPA and industry standards.
Why must technicians use recovery equipment specifically rated for flammable refrigerants when recovering A2L refrigerants?
Answer: To prevent ignition from spark-producing components inside standard recovery machines
A2L refrigerants are mildly flammable, so recovery equipment must be listed and rated for flammable refrigerants to eliminate internal ignition sources such as motor brushes and switches that could ignite refrigerant-air mixtures.
What does 'temperature glide' mean in the context of zeotropic A2L blends like R-454B?
Answer: The difference between dew point and bubble point temperatures of a blend at a given pressure
Temperature glide is the difference between the dew point (saturated vapor) and bubble point (saturated liquid) temperatures of a zeotropic blend at a given pressure, which affects system performance and superheat/subcooling measurements.
After completing a retrofit and recharging a system with an A2L refrigerant, what safety step must be performed before returning the equipment to service?
Answer: Perform a thorough leak check to verify no refrigerant leaks exist before returning to service
A thorough leak check is mandatory after any retrofit involving A2L refrigerants to confirm no flammable refrigerant is leaking into an enclosed or occupied space before the system is returned to service.