EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Medium
A technician is performing a recovery of R-123 from a low-pressure chiller. The recovery unit is operating, but the recovery rate is very slow, and the pressure in the chiller is not decreasing as expected. Which of the following is a common cause for a slow recovery rate in a low-pressure system?
- AThe refrigerant hoses are too short and have too large a diameter.
- BThe system's isolation valves are fully open, allowing maximum flow.
- CThe water temperature entering the recovery unit's condenser is too high.
- DThe recovery unit's compressor is oversized for the system capacity.
Show answer & explanationAnswer & explanation
Correct answer: C. The water temperature entering the recovery unit's condenser is too high.
A high water temperature entering the recovery unit's condenser reduces its efficiency, making it harder to condense the refrigerant vapor, thus slowing down the recovery process. The recovery unit relies on efficient condensation to create a pressure differential.
Why the other options are wrong
- A. Short, large-diameter hoses would reduce pressure drop and improve recovery speed, not slow it down.
- B. Fully open isolation valves are necessary for efficient recovery; if they were closed, recovery would stop or be severely restricted, but not simply 'slow.'
- D. An oversized compressor would generally lead to a faster recovery, not a slower one.
Low-Pressure Recovery Rate Factors
Several factors can significantly impact the speed and efficiency of refrigerant recovery from low-pressure systems, primarily related to temperature and pressure management.
- High ambient temperature can slow recovery.
- High condenser water temperature in the recovery unit slows recovery.
- Restrictions in hoses or filters reduce recovery rate.
Memory trick: Cool the condenser, open the path, or the recovery will last!