Installation, Maintenance & Repair Procedures Flashcards

When installing refrigerant piping, what is the maximum recommended horizontal suction line pitch to ensure proper oil return to the compressor?

Answer: 1/4 inch per foot downward in direction of flow

Horizontal suction lines should slope 1/4 inch per foot downward in the direction of refrigerant flow to assist oil return to the compressor via gravity.

During maintenance of a cooling tower, a technician finds biological growth (Legionella risk). What is the immediate required action?

Answer: Perform shock chlorination and notify the facility manager

Biological growth in cooling towers poses a Legionella health hazard requiring immediate shock chlorination treatment and notification of facility management per safety protocols.

A technician notices that a newly installed evaporator coil has frost forming only on the lower half of the coil. What is the most likely cause?

Answer: Low airflow across the evaporator

Frost forming on only part of the coil indicates insufficient airflow, preventing the upper portion from absorbing enough heat to keep that section above freezing.

When replacing a TXV on a refrigeration system, what critical adjustment step is required after installation?

Answer: Set the valve superheat to match system design specifications using bulb placement and stem adjustment

After TXV replacement, superheat must be measured and the valve adjusted (by turning the stem) so system superheat matches design specifications, typically 8–12°F for comfort cooling.

What is the required procedure when connecting a manifold gauge set to an operating system for pressure readings?

Answer: Connect hoses with manifold hand valves closed, then open service port valves slowly

Manifold hand valves should be closed before connecting to prevent refrigerant release, then service port valves are opened slowly to take readings safely.

A refrigeration system with an electronic expansion valve (EEV) is hunting (oscillating superheat). What is the best corrective action?

Answer: Adjust the EEV controller's proportional-integral (PI) gain settings

EEV hunting is typically caused by improper PI gain settings in the controller; adjusting these parameters stabilizes valve response and eliminates oscillation.

When decommissioning a system with a refrigerant blend, which recovery method is preferred to minimize fractionation?

Answer: Liquid recovery followed by vapor recovery

Liquid recovery first (followed by vapor recovery) minimizes fractionation of blended refrigerants by keeping the components together rather than allowing lighter components to boil off preferentially.