Heat pumps · Error codes · Immergas
PUMP-E21Immergas · MAGIS M monobloc R32 (M4-M30 T) - sold in UK as Alpha Magis M
PUMP-E21 on an Immergas MAGIS M monobloc R32 - sold in UK as Alpha Magis M: Circulation pump LED code: Overload
Short answer
On an Immergas heat pump, PUMP-E21 means: Circulation pump LED code: Overload. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Circulation pump LED code: Overload.
Part involved: primary circulation pump (18-30 kW models).
Likely causes:
- Motor slow / pump operated outside specifications (e.g. high module temperature); also shown as warning.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Pump switches off and tries a cyclical restart (all fault codes except E10).
What you can check
- Check the consumer-unit breaker/isolator is on.
- Note the code on the control panel and contact the installer / Alpha-Immergas authorised service.
What the engineer will check
- Request customer service / check environmental conditions.
Who to ask for: heating engineer (hydronics).
What you might notice
Sources
- MAGIS M4-30 Block heat pumps - Use and Installation - Instructions and warnings (IE edition), *1.046978ENG* ↗ · 1.046978ENG · page 101 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026