Why does a purge unit that runs around the clock cost the owner refrigerant as well as electricity?
Correct Answer
A) Each purge cycle carries some refrigerant vapor out along with the air it discharges
The gas the purge unit pulls from the condenser is a mixture of air and refrigerant vapor. A good purge unit separates most of the refrigerant and returns it, but no purge is perfect, so every discharge cycle sends a little refrigerant out with the air. Multiply that by continuous operation over a season and the losses become significant. That is why purge efficiency matters and why fixing the air leak is the real answer rather than tolerating the run time.
Why This Is the Correct Answer
Non-condensable gas leaving the machine is never pure air. It carries refrigerant vapor mixed in with it, and whatever the purge unit fails to separate goes out the discharge. Continuous operation multiplies a small per cycle loss into a large annual one, which is why the leak itself has to be fixed.
Why the Other Options Are Wrong
Option B: The purge unit condenses refrigerant into its own tank and holds it out of service permanently
A purge unit returns the refrigerant it recovers to the chiller rather than permanently storing it, so this is not where the loss comes from.
Option C: Continuous running overheats the refrigerant and breaks it down into acid
Refrigerant breakdown into acid is driven by heat, moisture and contamination in the system, not by the purge unit's run time.
Option D: The purge unit draws liquid refrigerant out of the bottom of the evaporator
The purge takes suction from the top of the condenser, in the gas space. It is not positioned to draw liquid out of the evaporator.
Memory Technique
Air comes in the leak, refrigerant goes out the purge. The purge is the exhaust pipe.
Reference Hint
Purge discharge carries refrigerant vapor along with non-condensables, so high purge run time equals refrigerant loss.
More epa-608-type-3 Questions
Some jobs on a chiller count as a major repair under the refrigerant rules, which changes what a technician is allowed to do with a badly leaking machine. Which job falls into that category?
An owner asks how many pounds of refrigerant the rules allow to be left inside a chiller once the recovery has been signed off. What is the correct answer to give him?
The motor of a hermetic centrifugal chiller sits inside the pressure boundary rather than outside it on a shaft. What follows from that construction?
An oxygen monitor is used to decide whether a chiller machine room is safe to enter after a refrigerant release. Below what oxygen reading is the atmosphere treated as oxygen deficient?
A low-pressure chiller's rupture disc has a discharge line running from it. Where does that line have to terminate?
A refrigerant vapor detector in a chiller machine room reaches its alarm level. Besides sounding, what is that alarm expected to do?
Which piece of equipment requires a technician to hold Type III certification before it may be serviced?
What property of the refrigerant is what actually places an appliance into the low-pressure category?
During normal operation, what condition exists inside the evaporator of a running low-pressure centrifugal chiller?
In what unit is the required final recovery vacuum for a low-pressure appliance normally expressed?
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