Heat pumps · Error codes · ELCO
E3ELCO · AEROTOP L (054/061/065/079/088) R32 commercial air-to-water
E3 on an ELCO AEROTOP L R32 commercial air-to-water: Total outlet water temperature probe Tw fault (master unit only)
Short answer
On an ELCO heat pump, E3 means: Total outlet water temperature probe Tw fault (master unit only). 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: Total outlet water temperature probe Tw fault (master unit only).
When it shows: With 2+ units check Tw sensor; with 1 unit Tw = Two by default.
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 error code shown and give it to your installer / service engineer.
What the engineer will check
- Check probe wiring/connector and resistance; replace probe.
Who to ask for: heat pump / electrical.
Sources
- AEROTOP L Air-Water Heat Pump - User Manual for Authorized Service Technicians (no. 420011134100) ↗ · 420011134100 · page 56 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026