Applicable Systems
Wilo Circulator Pump
Symptoms
The Wilo pump displays alarm W012, indicating insufficient system pressure. The pump is not maintaining the required system pressure, which may be caused by pump wear or system demand exceeding capacity.
Possible Causes
- Pump impeller worn or trimmed below the original diameter
- System demand increased beyond the original design flow
- Control valve stuck open or bypass valve inadvertently opened
Troubleshooting Steps
- Step 1: Check the pump operating point against the original performance curve
Operating point is on the curve for the current impeller diameter - Step 2: Measure system flow and compare to design values
Flow rate matches the system design with no unexplained increase - Step 3: Inspect all control and bypass valves for correct position
Control valves respond to signals and bypass valves are closed
How to Reset
To reset: 1) If impeller is worn, replace with a new one. 2) Adjust system demand or add pump capacity if required. 3) Correct valve positions. 4) Restart and verify pressure.
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Source: Wilo Pump Installation and Operating Manual, Wilo SE
Category: Pump
Published: 2026-10-08
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