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Heat pumps
Heat pumps · Error codes · Vaillant
S.315Vaillant · geoTHERM mini (VWS 30/4, VWS 36/4.1)

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
SeverityWarning

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

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026