What does error code F.22 u Protherm mean and how to fix it?

Insufficient water in heating system (pressure below 0.6 bar). Troubleshooting & fix: Open the filling valve underneath the boiler and pressurize to 1.2 – 1.5 bar; replace the clogged water pressure sensor if needed.

What does error code F.28 / F.29 u Protherm mean and how to fix it?

Ignition failure / flame loss. Troubleshooting & fix: Dirty ionization electrode, blocked condensate trap/siphon, or gas valve fault.

What does error code F.20 u Protherm mean and how to fix it?

Boiler overheating (high-limit safety thermostat tripped). Troubleshooting & fix: Faulty Wilo/Grundfos circulation pump or seized 3-way diverter valve.

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Technical Diagnostics & Fault Codes • Gas & Electric Boilers (Panther / Ray / Gepard)

Protherm Fault Codes F.22, F.28, F.75, F.10, F.20 – Error Code Meaning, Troubleshooting & Repair

Complete diagnostic table of the most common faults for Protherm (Gas & Electric Boilers (Panther / Ray / Gepard)) with quick troubleshooting steps and links to replacement parts:

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Error Code Reference Table for Protherm and step-by-step repair procedure:

Error Code	Meaning / Fault Symptom	Most Common Cause & Repair Procedure
F.22	Insufficient water in heating system (pressure below 0.6 bar)	Open the filling valve underneath the boiler and pressurize to 1.2 – 1.5 bar; replace the clogged water pressure sensor if needed.
F.28 / F.29	Ignition failure / flame loss	Dirty ionization electrode, blocked condensate trap/siphon, or gas valve fault.
F.20	Boiler overheating (high-limit safety thermostat tripped)	Faulty Wilo/Grundfos circulation pump or seized 3-way diverter valve.