- Boilers
- Tankless gas water heater
F50
Cointra F50 on gas water heater: modulating gas valve fault
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
On Cointra CPE T and SUPREME E TS room-sealed gas water heaters, F50 indicates a gas valve fault caused by an interrupted modulating actuator wire or a defective gas valve. Because F codes are temporary lockouts, RESET will not clear it: switch the heater off and call a registered gas technician.
Safety first
Stop and check this first
- Never open the casing, tamper with sealed adjustment devices or touch the gas valve yourself; Cointra requires disconnecting the electrical supply and closing the gas tap before a registered technician works inside.
- Disconnecting the electricity or gas supply disables the built-in frost protection; if the water heater will remain off in freezing conditions below -5 °C, the manual advises draining all water from the appliance.
Safe checks you can perform
- Verify code F50 and any alternating d3 / d4 waiting messages on the LCD
- See whether F50 clears automatically once hot water demand stops
- Switch the heater off with ON/OFF and close the upstream gas shut-off tap
Leave these tasks to a qualified professional
- Do not attempt this professional task: Inspect and test the modulating actuator wiring harness
- Do not attempt this professional task: Test the modulating gas valve and replace with a genuine part if defective
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.
Inspect and test the modulating actuator wiring harness
What they doAfter isolating the 230 V electrical supply and closing the gas valve, the registered technician removes screws A to open the front cover and checks continuity and plug seating on the modulating actuator harness (connector I in Figure 11 of the SUPREME E TS manual).
They must show youthe condition of the electrical plug on the gas valve and the continuity measurement along the modulating actuator wires.
In writingthe wiring inspection result, electrical measurements recorded, and whether repairing the harness resolved F50.
Test the modulating gas valve and replace with a genuine part if defective
What they doIf the harness is sound, the authorised technician tests the gas valve (on SUPREME E TS, TYPE SGV100 24 Vdc with ~65 ohm and ~24 ohm coils and pressure test points A and B), replaces it with an original Cointra valve if faulty, and checks gas tightness and burner modulation.
They must show youthe coil resistance readings on the gas valve, the gas tightness test and the burner pressure modulation check.
In writingthe original Cointra part number fitted, the verified minimum and maximum burner pressures, and the gas safety sign-off.
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.
Verify code F50 and any alternating d3 / d4 waiting messages on the LCD
- Who:
- you, looking only at the external control panel.
- How:
- inspect the LCD screen without opening the casing to confirm that F50 is flashing with the fault symbol (or alternating with d3 and d4 during the waiting period), distinguishing it from permanent codes A09 and A16.
- Result that matters:
- confirming that the water heater is in temporary lockout F50 for the modulating gas valve circuit.
- If the screen displays A09 or A16 instead of F50:
- those are permanent A-series gas valve lockouts.
- If F50 stays on the LCD or alternates with d3 and d4:
- do not press RESET repeatedly, as F codes are temporary lockouts.
- Evidence to keep:
- photo of the LCD panel showing F50 and the model data plate.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
See whether F50 clears automatically once hot water demand stops
- Who:
- you, provided there is no smell of gas.
- How:
- close the domestic hot water tap, wait briefly without pressing RESET, and check whether the temporary F50 lockout clears on its own when the reading returns to the normal operating range.
- Result that matters:
- determining whether the modulating actuator signal recovered or remains permanently interrupted.
- If F50 disappears and the normal DHW outlet temperature returns:
- note the time and book a check if it recurs.
- If F50 remains flashing on the screen:
- proceed to switch the appliance off as instructed by Cointra.
- Evidence to keep:
- note of whether F50 stayed active with all hot water taps closed.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Switch the heater off with ON/OFF and close the upstream gas shut-off tap
- Who:
- you, using only the external controls.
- How:
- press the ON/OFF key on the control panel for 1 second (key 5 on CPE T; key 7 on SUPREME E TS) until the OFF symbol appears, switch off the external electrical isolator, and close the gas shut-off valve ahead of the appliance.
- Result that matters:
- leaving the gas water heater safely isolated until a registered gas technician inspects it.
- If the unit is off and the gas valve is closed:
- arrange a visit from an authorised gas technician.
- If you smell gas near the heater:
- do not touch any buttons or electrical switches, ventilate the room and leave immediately.
- Evidence to keep:
- record of the exact model (CPE T 11/14/17 or SUPREME 11/14/17 E TS) and gas type (G20, G30 or G31).
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.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
- Boilers
- Brand
- Cointra
- Product type
- Tankless gas water heater
Known code variants
- Anomalía F50 Ferroli
- BlueHelix F50
- calentador Cointra F50
- Cointra CPE T F50
- Cointra F50
- Cointra gas water heater F50
- Cointra Supreme E TS F50
- Cointra water heater error F50
- error F50 calentador Cointra
- Error F50 Ferroli
- F 50
- F-50
- F50
- Ferroli error F50
- Ferroli F50
- Ferroli F50 boiler
What it means
According to the official use, installation and maintenance manuals for the Cointra CPE T (11, 14 and 17 Low NOx, code A73022110 Rev.03) and SUPREME E TS (11, 14 and 17, code 3541A273 Rev.01) room-sealed instantaneous gas water heaters, code F50 denotes a gas valve fault (Anomalía de la válvula del gas) with two documented causes: interrupted modulating actuator wiring or a faulty gas valve. Unlike permanent A09 and A16 lockouts, F50 starts with F and triggers a temporary lockout that alternates d3 and d4 while waiting. Other Cointra models may differ. On its own, F50 never proves that the gas valve itself is broken.
Warnings and stop conditions
- Higheditorial warning
Never open the casing, tamper with sealed adjustment devices or touch the gas valve yourself; Cointra requires disconnecting the electrical supply and closing the gas tap before a registered technician works inside.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
- Mediumeditorial warning
Disconnecting the electricity or gas supply disables the built-in frost protection; if the water heater will remain off in freezing conditions below -5 °C, the manual advises draining all water from the appliance.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Symptoms and causes
Probable causes · in order
- Interrupted wiring to the modulating actuator on the gas valveCommon
The first cause listed in both the CPE T and SUPREME E TS fault tables for F50 is an open circuit or loose connection in the modulating actuator harness.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
- Faulty modulating gas valve assembly or actuator coilPossible
The second documented cause is a failure in the gas valve itself (item 12 on CPE T; item 44, TYPE SGV100 24 Vdc class B+A on SUPREME E TS), requiring inspection and replacement if necessary.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Virtual technician
Does F50 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
Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03)
Cointra · 2018 · manual
- 2
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