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Reduced Cooling Capacity Due to Long Piping

Likely causes

Equivalent piping length exceeds 165m — excessive refrigerant pressure loss

Check: Sum actual pipe length + elbow/valve equivalent lengths → check if exceeds 165m → measure suction/discharge pressure at farthest indoor unit to confirm pressure loss

What to do: Rework piping route optimization → consider relocating outdoor unit → calculate pressure loss and add refrigerant (add standard amount per 0.05 MPa pressure differential)

Indoor/outdoor unit elevation difference exceeds 50m — refrigerant imbalance due to gravity

Check: Calculate indoor-outdoor unit installation height difference → check if exceeds 50m → check for oil shortage symptoms when outdoor unit installed above

What to do: Add oil trap installation → recalculate refrigerant charge amount (altitude correction) → review feasibility of relocating outdoor unit

Additional refrigerant charge not performed — long pipe distance compensation charge omitted

Check: Check commissioning records for additional refrigerant charge execution → verify refrigerant pressure at outdoor unit service port → measure suction superheat (normal 5–8°C)

What to do: Calculate additional charge amount per manufacturer commissioning manual → charge accurately using scale weighing method → verify suction superheat 5–8°C after charging

Field tip

First check for long-pipe system capacity loss: compare farthest indoor unit suction pressure with design pressure — if difference is 0.05 MPa or more, consider additional charging.

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