EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Hard
A technician observes that a low-pressure chiller's purge unit is continuously running. What is the most likely cause for this condition?
- AThe chiller's condenser water temperature is too low.
- BThe refrigerant charge is critically low.
- CThe system is properly charged and operating efficiently.
- DThere is a significant air leak into the chiller.
Show answer & explanationAnswer & explanation
Correct answer: D. There is a significant air leak into the chiller.
A continuously running purge unit indicates that it is constantly trying to remove non-condensable gases from the system. The most common source of non-condensables in a low-pressure chiller is air leaking into the system, especially when the system pressure drops below atmospheric pressure.
Why the other options are wrong
- A. Low condenser water temperature would typically reduce the need for purging, not increase it.
- B. Critically low refrigerant charge would typically lead to low suction pressure, but not necessarily continuous purge unit operation unless it's accompanied by air ingress.
- C. Proper operation means the purge unit runs intermittently, not continuously.
Continuous Purge Unit Operation
A diagnostic symptom in low-pressure chillers indicating a persistent ingress of non-condensable gases, typically air.
- Purge units remove non-condensables (air).
- Continuous operation means a constant supply of non-condensables.
- Most likely caused by a leak allowing air into the system.
Memory trick: Purge non-stop? Must be a hole, hop!