The Importance of Oil Return in Split Systems
Compressor oil lubricates the crankshaft and moving parts. Inadequate oil return can cause severe wear, leading to compressor failure within hours. For split systems where the compressor is separate from the evaporator, proper piping design is essential to ensure oil reliably returns to the compressor.
Key Installation Practices for Efficient Oil Return
1️⃣ Copper Piping Design & Installation
- Minimize Length: Keep the suction line as short and direct as possible.
- Reduce Welds: Limit the number of brazed joints to decrease potential leak points and oil traps.
- Correct Slope: When the compressor is above the evaporator, slope the suction line downward toward the compressor at a minimum of 1:120 (1 cm per 1.2 m).
- Avoid Traps: Ensure no low points or traps in the suction line where oil can accumulate.
- Use P-Traps or Loops: If the evaporator is above the compressor, install a P-trap at the bottom of the vertical riser to aid oil return.
2️⃣ System Commissioning & Oil Return Check
- Calculate Oil Return Speed: After installation and pressure testing, monitor how long it takes for oil to return after compressor start-up during commissioning.
- Use Sight Glasses: Install sight glasses in the suction line to visually confirm oil return.
- Verify Oil Levels: Check the compressor oil level before, during, and after extended run times to ensure stable levels.
3️⃣ Additional Best Practices
- Proper Pipe Sizing: Use correctly sized copper pipes to maintain adequate refrigerant velocity for carrying oil.
- Insulation: Fully insulate the suction line to prevent condensation and maintain refrigerant temperature.
- Regular Maintenance: Schedule periodic checks for oil level and system performance.
Pro Tip: For long suction line runs or systems with significant elevation changes, consider adding an oil separator for reliable lubrication.
Need Expert Guidance on Your Refrigeration Installation?
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