F.714 on a Vaillant heat pump: Environment circuit: Pressure too low
Short answer
On a Vaillant heat pump, F.714 means: Environment circuit: Pressure too low. 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
On the flexoTHERM exclusive (VWF ../4)
The manual says: Environment circuit: Pressure too low.
Part involved: Pressure too low.
Likely causes:
- Pressure loss in the environment circuit due to leakages or air pockets; Environment circuit pressure sensor defective.
On the geoTHERM mini (VWS 30/4, VWS 36/4.1)
The manual says: Environment circuit: Pressure too low.
Part involved: Pressure too low.
Likely causes:
- Pressure drop in the environment circuit due to leakages or air pockets; Environment circuit pressure sensor defective.
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.
Resetting itself: yes - restarts when pressure above minimum (0.5 bar min, 0.7 bar operating).
Manual reset: not required once pressure restored.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Read the building/environment circuit pressure in Live Monitor. The flexoTHERM operating instructions say to inform your competent person so that they can top up the heating water (F.723) or brine fluid (F.714).
What the engineer will check
On the flexoTHERM exclusive (VWF ../4)
- Check the environment circuit for leaks; Top up the medium (brine-to-water), purge; Check the quality of the plug contact on the PCB and on the cable harness; Check that the pressure sensor is working correctly; Replace the pressure sensor.
Who to ask for: Vaillant-trained heat pump installer/engineer (MCS-certified installer).
Certification: MCS ground-source installer; F-gas certificate for refrigerant work.
On the geoTHERM mini (VWS 30/4, VWS 36/4.1)
- Check the environment circuit for leaks; Top up the medium (brine/water), purge; Check the quality of the plug contact on the PCB and on the cable harness; Check that the pressure sensor works correctly; Replace the pressure sensor.
Who to ask for: Vaillant-trained heat pump installer/engineer (MCS-certified installer).
Certification: MCS ground-source installer; F-gas certificate for refrigerant work.
What you might notice
Sources
- flexoTHERM exclusive VWF 57/4 - 197/4 400V installation and maintenance instructions ↗ · 0020213394_05 · page flexoTHERM 400 V 0020213394_05 p.52; flexoTHERM 230 V 0020213395_04 p.47 · Reviewed 23 September 2026
- geoTHERM mini VWS 36/4.1 230 V installation manual ↗ · 0020250181_00 · page geoTHERM mini 0020250181_00 p.37 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026