Refrigerant pipes connect your indoor and outdoor AC units. Proper sizing is crucial for efficiency, performance, and equipment longevity.
Why Pipe Size Matters
Too Small
- Restricts refrigerant flow
- Reduces cooling capacity
- Increases compressor workload
- Higher energy consumption
- Premature compressor failure
Too Large
- Reduced refrigerant velocity
- Poor oil return to compressor
- Higher installation cost
- Potential capacity loss
Standard Pipe Sizes
By AC Capacity
- 9,000-12,000 BTU: 1/4" liquid, 3/8" suction
- 18,000-24,000 BTU: 1/4" or 3/8" liquid, 1/2" suction
- 30,000-36,000 BTU: 3/8" liquid, 5/8" suction
- 48,000+ BTU: 3/8" liquid, 3/4" suction
Pipe Length Considerations
Maximum Length
Most residential splits allow 15-25 meters maximum. Beyond this, efficiency drops significantly.
Elevation Changes
Vertical runs affect performance:
- Each 3 meters of vertical rise = ~1 meter horizontal equivalent
- Outdoor unit below indoor: easier oil return
- Outdoor unit above indoor: may need oil traps
Long Runs
For runs over 15 meters:
- Consider upsizing pipes
- May need additional refrigerant charge
- Professional calculation recommended
Installation Tips
- Insulate both liquid and suction lines
- Avoid sharp bends (use long-radius curves)
- Slope pipes slightly toward outdoor unit
- Properly braze connections (no leaks)
Calculate Your Requirements
Use our Pipe Length Sizing Tool to determine proper sizes for your installation, and Multi-Split Planner for complex systems.