F.025 error code
Hermann Saunier Duval Thema Condens F.025 error code – Flue-gas temperature too high
What does Hermann Saunier Duval Thema Condens FlameFit boiler family F.025 mean?
The official Thema Condens diagnostic table defines F.025 as: Flue-gas temperature too high. Code availability can vary by exact model and installed accessories.
The code identifies the condition detected by the product; it does not always identify the failed component on its own. Confirm the full code and exact model before ordering parts or attempting a reset.
The Hermann Saunier Duval Thema Condens FlameFit boiler family F.025 error code indicates the official Thema Condens diagnostic table defines F.025 as: Flue-gas temperature too high. Code availability can vary by exact model and installed accessories. This guide explains what the code means, the symptoms and likely causes, the checks that are safe to make, and when to stop and arrange an authorised repair.
Symptoms you may notice
The burner may be inhibited or locked out because a combustion, ignition, flue or condensate safety check failed.
Common causes
Gas supply or adjustment, ignition or flame-sensing components, combustion-air or flue restriction, condensate blockage, gas-valve control, wiring or electronics.
Before you start troubleshooting
Use the display, rating label or product menu to confirm the exact model. Similar-looking codes can have different meanings across product generations and regions.
- Record the complete code before switching the equipment off.
- Check only user-accessible controls, filters and external connections described in the manual.
- Do not open gas, refrigerant, combustion or electrical compartments.
Troubleshooting steps
Record F.025, the complete model and what the boiler was doing. Check only visible pressure, user controls and safely accessible external terminals. Use the official diagnostic table for the exact variant; internal sensor, pump, flue, combustion, gas and electrical tests require a qualified technician.
Can you fix this error code yourself?
The safest next step depends on the exact model and the cause behind the code. External checks may help, but a returning fault needs professional diagnosis.
A successful reset is not proof that the underlying issue is fixed. If F.025 reappears, note when it happens and give that information to the service engineer.
Reset instructions
Use the reset procedure stated in the exact boiler user instructions only after safe external checks. Do not repeatedly reset a returning fault or override an automatic safety shutdown.
Applicable products and models
Thema Condens FlameFit boiler familyThema Condens 25 kW; 30 kW; 35 kW (code availability model-dependent)Current manual revision 0020292725_07When to contact a professional
Contact an authorised Hermann Saunier Duval technician whenever the code persists, internal access is required, or diagnosis involves gas, combustion, flue components, pumps, sensors, controls or electrical testing.
Frequently asked questions
What does Hermann Saunier Duval Thema Condens FlameFit boiler family F.025 mean?
The official Thema Condens diagnostic table defines F.025 as: Flue-gas temperature too high. Code availability can vary by exact model and installed accessories.
Can I fix Hermann Saunier Duval Thema Condens FlameFit boiler family F.025 myself?
Some external checks may be suitable for the user, but the result depends on the exact model and cause. Use the official manual and arrange service if the code returns.
Should I reset the product after code F.025?
Use the reset procedure stated in the exact boiler user instructions only after safe external checks. Do not repeatedly reset a returning fault or override an automatic safety shutdown.
When should I arrange a repair?
Contact an authorised Hermann Saunier Duval technician whenever the code persists, internal access is required, or diagnosis involves gas, combustion, flue components, pumps, sensors, controls or electrical testing.