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Heat pumps · Error codes · Vaillant
S.275Vaillant

S.275 on a Vaillant heat pump: Building circuit: Flow rate too low Building circuit pump defective. All consumers in the heating system are closed. The values fall below the specific minimum volume flows. Check that the dirt filter is permeable. Check the stopcocks and thermostatic valves. Ensure that the flow rate …

Short answer

On a Vaillant heat pump, S.275 means: Building circuit: Flow rate too low Building circuit pump defective. All consumers in the heating system are closed. The values fall below the specific minimum volume flows. Check that the dirt filter is permeable. Check the stopcocks and thermostatic valves. Ensure that the flow rate …. The heat pump keeps running with some functions stopped. The wording differs by model range — each is shown below.

Reviewed 23 September 2026 · 3 sources

What it means

On the aroTHERM plus (VWL ../6 A)

The manual says: Building circuit: Flow rate too low Building circuit pump defective. All consumers in the heating system are closed. The values fall below the specific minimum volume flows. Check that the dirt filter is permeable. Check the stopcocks and thermostatic valves. Ensure that the flow rate ….

Part involved: Heat pump control (status/Live Monitor).

When it shows: Building circuit: Flow rate too low Building circuit pump defective. All consumers in the heating system are closed. The values fall below the specific minimum volume flows. Check that the dirt filter is permeable. Check the stopcocks and thermostatic valves. Ensure that the flow rate ….

Likely causes:

  • Building circuit: Flow rate too low Building circuit pump defective. All consumers in the heating system are closed. The values fall below the specific minimum volume flows. Check that the dirt filter is permeable. Check the stopcocks and thermostatic valves. Ensure that the flow rate ….

On the flexoTHERM exclusive (VWF ../4)

The manual says: Building circuit: Flow rate too low.

Part involved: Heat pump control (status/Live Monitor).

When it shows: See official description.

Likely causes:

  • Building circuit: Flow rate too low.

On the geoTHERM mini (VWS 30/4, VWS 36/4.1)

The manual says: Building circuit: Flow rate too low.

Part involved: Heat pump control (status/Live Monitor).

When it shows: See official description.

Likely causes:

  • Building circuit: Flow rate too low.

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

What owners and engineers report

6 owner and engineer reports mention this.

  • Keeps stopping / cutting out on the aroTHERM plus (VWL ../6 A): 6 reports

Sources

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

Reviewed: 23 September 2026