Heat pumps · Error codes · Climaveneta / De Longhi Professional
Er64Climaveneta / De Longhi Professional · De'Longhi Professional / Climaveneta BWR MTD and MTD2 brine-to-water heat pump
Er64 on a Climaveneta / De Longhi Professional De'Longhi Professional / Climaveneta BWR MTD and MTD2 brine-to-water heat pump: Faulty BT3 source water outlet sensor (automatic reset)
Short answer
On a Climaveneta / De Longhi Professional heat pump, Er64 means: Faulty BT3 source water outlet sensor (automatic reset). 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: Faulty BT3 source water outlet sensor (automatic reset).
Likely causes:
- Sensor or wiring fault.
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.
What you can check
- 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
- Check electrical connections; replace component.
Who to ask for: refrigeration / heat pump engineer.
Certification: Electrical competence for work inside the unit.
What you might notice
Sources
- Climaveneta WWR MTD - MTD/S, BWR MTD - MTD/S Installation and User Manual (GB 03/2010) ↗ · GB 03/2010 · page 49 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026