Er01 on a Climaveneta / De Longhi Professional heat pump: High pressure switch tripped; manual reset after 3 activations in one hour; incorrect phase connection (three-phase models)
Short answer
On a Climaveneta / De Longhi Professional heat pump, Er01 means: High pressure switch tripped; manual reset after 3 activations in one hour; incorrect phase connection (three-phase models). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the De'Longhi Professional / Climaveneta AWR MTD reverse-cycle air/water heat pump with DHW
The manual says: High pressure switch tripped; manual reset after 3 activations in one hour; incorrect phase connection (three-phase models).
Likely causes:
- High discharge pressure.
- Phase sequence (3-ph).
On the De'Longhi Professional / Climaveneta BWR MTD and MTD2 brine-to-water heat pump
The manual says: High pressure switch tripped; manual reset after 3 activations in one hour; incorrect phase connection (three-phase).
Likely causes:
- Refrigerant pressure outside limits.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
On the De'Longhi Professional / Climaveneta AWR MTD reverse-cycle air/water heat pump with DHW
- Note the code/LED pattern and the model from the rating plate, then contact a heat pump/refrigeration engineer.
- Check the heat pump's breaker/isolator at the consumer unit is on.
- Check the outdoor unit is not blocked by leaves, snow or debris.
On the De'Longhi Professional / Climaveneta BWR MTD and MTD2 brine-to-water heat pump
- Note the code/LED pattern and the model from the rating plate, then contact a heat pump/refrigeration engineer.
- Check the heat pump's breaker/isolator at the consumer unit is on.
What the engineer will check
On the De'Longhi Professional / Climaveneta AWR MTD reverse-cycle air/water heat pump with DHW
- Check high discharge pressure.
- Swap two phases if sequence wrong.
- Check HP switch and wiring.
Who to ask for: refrigeration / heat pump engineer.
Certification: F-gas certification (refrigerant circuit work) and electrical competence.
On the De'Longhi Professional / Climaveneta BWR MTD and MTD2 brine-to-water heat pump
- Check discharge/suction pressures and pressure switches.
- Check phase order (3-ph).
Who to ask for: refrigeration / heat pump engineer.
Certification: F-gas certification (refrigerant circuit work) and electrical competence.
What you might notice
Sources
- Climaveneta AWR MTD / AWR MTD/B 0011-0061 Installation - Operating - Service Manual (GB 01/2009) ↗ · GB 01/2009 · page 47 · Reviewed 23 September 2026
- Climaveneta WWR MTD - MTD/S, BWR MTD - MTD/S Installation and User Manual (GB 03/2010) ↗ · GB 03/2010 · page 48 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026