Refrigeration Flashcards
7 cards from real HVAC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Refrigeration flashcards as text
What is the purpose of a hot gas bypass valve in a refrigeration system?
Answer: Maintain minimum evaporator load by diverting hot gas to the evaporator inlet
A hot gas bypass valve diverts discharge gas to the evaporator inlet to maintain minimum system load and prevent evaporator freeze-up during low-load conditions.
Which refrigerant is classified as A2L and is being adopted as an R-410A replacement?
Answer: R-454B
R-454B (sold as Puron Advance) is an A2L refrigerant with a GWP of 466 being adopted as the primary R-410A replacement in residential systems.
In a refrigeration cycle, what happens to the refrigerant in the condenser?
Answer: It rejects heat and condenses from vapor to liquid
In the condenser, high-pressure refrigerant vapor rejects heat to the outdoor air or water and condenses into a liquid.
What is the purpose of crankcase heaters on a refrigeration compressor?
Answer: Prevent refrigerant from migrating to and mixing with the compressor oil during off cycles
Crankcase heaters keep the compressor oil warm during off cycles to prevent refrigerant from migrating into and diluting the oil, which can cause compressor damage on startup.
What is 'coefficient of performance' (COP) in refrigeration?
Answer: The ratio of refrigerating effect to compressor work input
COP is the ratio of the useful refrigerating effect (heat removed from the space) to the work input to the compressor, measuring the efficiency of a refrigeration system.
According to EPA Section 608 regulations, technicians must use which type of equipment when removing refrigerant from a system?
Answer: EPA-approved refrigerant recovery equipment
EPA Section 608 requires technicians to use approved recovery equipment to capture refrigerant and prohibits venting it into the atmosphere.
What condition is indicated when a refrigeration system has a high suction pressure and high discharge pressure simultaneously?
Answer: Refrigerant overcharge
High suction and high discharge pressures together typically indicate an overcharged system, where excess refrigerant raises pressures throughout the system.