F.731 on a Glow-worm GeniaAir: High-pressure switch has been triggered
Short answer
On a Glow-worm heat pump, F.731 means: High-pressure switch has been triggered. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: High-pressure switch has been triggered.
Part involved: High-pressure switch has been triggered.
Likely causes:
- Refrigerant pressure too high. The integrated high-pressure switch in the outdoor unit has tripped at 31.5 bar (g) or 32.5 bar (abs). Insufficient energy output via the condenser.
- Glow-worm trade page: Refrigerant high pressure switch open Fault in the electrical connection of the high pressure switch, high pressure switch fault, electronic expansion valve fault, 4 way valve fault, refrigerant flow too low, condenser blocked or restricted (see F.532), building circuit flow rate too high or too ….
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no - the fault remains displayed until the cause is eliminated.
Manual reset: yes - engineer resets the high-pressure switch (Installer level > Reset > Reset high-pressure switch) and carries out a manual reset.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Check the outdoor unit's air inlet and outlet are not blocked by leaves, debris, snow or ice build-up and clear any loose debris from around it (do not open the casing, poke the fins or use tools). Glow-worm's MiPro Sense operating instructions say always contact your competent person in the event of a fault message; until they arrive you may select a limp-home (back-up heater) setting on the control, which is expensive to run. If you smell gas/solvent near the outdoor unit or hear hissing, switch the heat pump off at the isolator, keep ignition sources away and call an engineer.
What the engineer will check
- Purge the building circuit. 2. Too low a volume flow as a result of closing single room controls in an underfloor heating system. 3. Check that the dirt filter that is in place is permeable. 4. Refrigerant flow rate too low (e.g. electronic expansion valve defective, 4-port diverter valve is mechanically blocked, filter is blocked). Inform customer service. 5. Cooling mode: Check the fan unit for dirt. 6. Check the high-pressure switch and high-pressure sensor. 7. Reset the high-pressure switch and carry out a manual reset on the product.
Who to ask for: F-gas certified refrigeration engineer with heat pump experience (R290 flammable-refrigerant competence required for aroTHERM plus / GeniaAir).
Certification: F-gas Category I (Regulation (EU) 517/2014 as retained in GB) certificate; flammable (R290) refrigerant training for R290 units.
What you might notice
Sources
- GeniaAir Appliance Interface installation and maintenance instructions ↗ · 8000043014_01 · page HPIM 7 8000043014_01 p.32 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026