S.315 on a Vaillant geoTHERM mini: Compressor circuit breaker open
Short answer
On a Vaillant heat pump, S.315 means: Compressor circuit breaker open. The heat pump keeps running with some functions stopped.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Compressor circuit breaker open.
Part involved: Heat pump control (status/Live Monitor).
When it shows: See official description.
Likely causes:
- Compressor circuit breaker open.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
The heat pump keeps running with some functions stopped.
Resetting itself: yes - status changes automatically with operating state.
Manual reset: not applicable.
What you can check
- Note the status code (Live Monitor). The heat pump will normally retry automatically; if a related F-code appears or heating/hot water stops, contact your installer.
What the engineer will check
- Read Live Monitor status and fault history; if the status persists or precedes an F-code, follow the corresponding F-code diagnostics in the installer fault table.
Who to ask for: Vaillant-trained heat pump installer/engineer (MCS-certified installer).
Certification: MCS installer certification; Vaillant product training recommended.
What you might notice
Sources
- geoTHERM mini VWS 36/4.1 230 V installation manual ↗ · 0020250181_00 · page geoTHERM mini 0020250181_00 p.36 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026