- Heat pumps
- Air-to-water heat pump
F731
Saunier Duval F.731 heat pump fault: high-pressure switch open
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
F.731 tells you the refrigerant high-pressure switch has tripped after several restarts. Usually the water side is not carrying the heat away. Check pressure and open zones, clear the outdoor unit and call a certified heat pump installer.
Safety first
Stop and check this first
- The Genia Air outdoor unit runs on R290, a flammable refrigerant. Keep its protective zone free of flames, sparks and sprays, and do not open panels: refrigerant circuit work is for qualified staff only.
Safe checks you can perform
- Read the fill pressure on the display
- Open the room thermostats and underfloor zones
- Outdoor unit grilles kept clear
- Report it rather than resetting yourself
Leave these tasks to a qualified professional
- Do not attempt this professional task: Purge the circuit and clean the strainers
- Do not attempt this professional task: Switch reset and run test
- Do not attempt this professional task: Refrigerant circuit check by certified staff
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Purge the circuit and clean the strainers
What they doThe installer bleeds the building circuit, inspects the dirt strainers and confirms the water flow reaches the minimum before looking at the refrigerant side.
They must show youthe measured flow rate against the manufacturer minimum and the state of the strainers.
In writingthe flow before and after, and what was cleaned or purged.
Switch reset and run test
What they doOnce the cause is fixed, the professional resets the high-pressure switch, restarts the product manually and lets it run until it is clear it no longer stops.
They must show youthe unit running with stable pressures after the reset.
In writingthe cause corrected, the reset date and how long the test lasted.
Refrigerant circuit check by certified staff
What they doAn F-gas certified technician checks the electronic expansion valve, the 4-way valve and the filter, and tests the high-pressure switch and sensor.
They must show yourefrigerant pressures and temperatures read on gauges or the service tool.
In writingthe readings, any replaced parts and the reason for each change.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Read the fill pressure on the display
- Who:
- you, from the tower control panel.
- How:
- check the filling pressure shown on the GeniaSet display. Saunier Duval gives 0.07 MPa (0.70 bar) as the minimum operating pressure for the heating circuit.
- Result that matters:
- a pressure of 0.7 bar or more.
- If it is lower:
- ask the authorised professional to top up and trace the water loss.
- If it is fine:
- go on to the underfloor zones.
- Evidence to keep:
- photo of the display with F.731 and the pressure.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01
Open the room thermostats and underfloor zones
- Who:
- you, no tools needed.
- How:
- raise the setpoint on each room thermostat or switch on zones you had turned off, so water can flow through as many loops as possible. The manual links F.731 to closed individual room controllers.
- Result that matters:
- most loops calling for heat and water circulating.
- If many zones were shut:
- leave them open and watch whether the code returns.
- If the zones were open already:
- write that down for the visiting technician.
- Evidence to keep:
- a list of the zones that were shut and when you opened them.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01
Outdoor unit grilles kept clear
- Who:
- you, outdoors, without removing any panel.
- How:
- remove leaves, branches, dirt or snow from the air inlet, the air outlet and the ventilation grille underneath, as the Genia Air outdoor unit manual asks. Pay particular attention if the code came up in cooling mode.
- Result that matters:
- free airflow all around the unit.
- If it was blocked:
- clear it by hand and note which mode the system was in.
- If it was clean:
- the cause is more likely on the water or refrigerant side.
- Evidence to keep:
- photos of the outdoor unit and of the mode shown on the display.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01 · Saunier Duval Genia Air HA 4-6 a HA 15-6 O B3, instrucciones de la unidad exterior 0020297943_00
Report it rather than resetting yourself
- Who:
- you.
- How:
- resetting the high-pressure switch and the manual restart are in the installer instructions. Note the code and since when it shows, and contact an authorised professional, as the operating manual tells you to.
- Result that matters:
- a complete report so the technician arrives informed.
- If the code had appeared before:
- say so, because earlier restarts are part of the diagnosis.
- If it is the first time:
- mention whether it came with severe cold or closed zones.
- Evidence to keep:
- a log of dates and times when F.731 was seen.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Heat pumps
- Brand
- Saunier Duval
- Product type
- Air-to-water heat pump
Known code variants
- error F.731 aerotermia Saunier Duval
- F731
- Genia Air F.731
- Genia Air Max F731
- GeniaSet F.731
- high pressure switch F.731
- presostato alta F.731
- Saunier Duval F731
- Saunier Duval heat pump F.731
What it means
On a Genia Air Max with GeniaSet tower, F.731 means refrigerant pressure exceeded the limit and the built-in high-pressure switch opened at 41.5 bar (g) or 42.5 bar (abs). Before the code appears, the heat pump stops for 15 minutes and restarts; after four failed restarts it locks out. The root issue is that the condenser cannot pass its energy to the water. The code by itself does not show that the switch or the compressor is broken. This information comes from the Spanish Saunier Duval manual, as no English edition was used.
Warnings and stop conditions
- Higheditorial warning
The Genia Air outdoor unit runs on R290, a flammable refrigerant. Keep its protective zone free of flames, sparks and sprays, and do not open panels: refrigerant circuit work is for qualified staff only.
Evidence: Saunier Duval Genia Air HA 4-6 a HA 15-6 O B3, instrucciones de la unidad exterior 0020297943_00
Symptoms and causes
Probable causes · in order
- Low water flow from closed zonesCommon
Saunier Duval names individual room controllers closing on an underfloor system as a reason for too little volume flow in the building circuit.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01
- Air in the circuit or blocked dirt strainersCommon
The fault table asks for the building circuit to be purged and for the dirt strainers to be checked so that water passes freely.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01
- Refrigerant flow too lowPossible
A faulty electronic expansion valve, a stuck 4-way valve or a clogged refrigerant filter limit the refrigerant flow; this is a job for technical service.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01
- Dirty fan unit in cooling modePossible
In cooling the outdoor unit rejects heat into the air; dirty fins or grilles make the pressure climb.
Evidence: Saunier Duval GeniaSet FW 200-6 y FEW 200-6, instrucciones de funcionamiento, instalación y mantenimiento 0020291590_01 · Saunier Duval Genia Air HA 4-6 a HA 15-6 O B3, instrucciones de la unidad exterior 0020297943_00
Virtual technician
Does F731 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
- 2
Saunier Duval Genia Air HA 4-6 a HA 15-6 O B3, instrucciones de la unidad exterior 0020297943_00
Saunier Duval · 2020 · manual
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