Heat pumps · Error codes · Atlantic
IF-23Atlantic
IF-23 on an Atlantic heat pump: Connection forbidden (series error)
Short answer
On an Atlantic heat pump, IF-23 means: Connection forbidden (series error). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manual says: Connection forbidden (series error).
Likely causes:
- Communication/connection fault between hydraulic unit and outdoor unit (or between boards), or incompatible combination.
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
- Check the heat pump isolator and consumer-unit breakers are on (do not open any casing).
- Note the error number/LED pattern shown and give it to your installer.
What the engineer will check
- Check interconnection cable and terminals between indoor and outdoor units.
- Check board connectors and unit combination.
Who to ask for: heat pump / electrical.
What you might notice
Sources
- alféa excellia duo Maintenance Document (U0546279_1738_EN_16) ↗ · U0546279_1738_EN_16 · page 69 · Reviewed 23 September 2026
- alféa extensa + Installation and operating manual (doc 1734-10, 1734-EN) ↗ · 1734-10 · page 75 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026