Saunier Duval Thema Condens 25-A faults
Identify the code and check the version of your boiler.
Models and version of the manual
25-A. It corresponds to Thema Condens 25-A, not to Thema MiConnect CS/1. The manual also covers AS variants: accessory notifications depend on the installation.
Consulted edition: Thema Condens 25-A / AS25-A / AS30-A manufacturer's manualThe control options, accessories, and versions may limit which notifications appear in each installation.
Locate the code on your screen.
These accesses lead to their entry in the table. They are not a classification of the most common faults: the manual does not provide incidence statistics.
- F.22
Safety shutdown: lack of water
- F.28
Start-up fault: ignition failed
- F.29
Operating fault: failed ignition attempts
- F.83
Fault: temperature adjustment in the supply and/or return temperature sensors
What to do without opening the boiler
- Note what you see.
Complete code, message, and pressure displayed by the equipment. Indicate whether it occurs when opening hot water, requesting heating, or in both cases.
- Identify the device.
Take a photo of the screen and the identification accessible without disassembling anything. Brand, model, and version help avoid confusing tables from different ranges.
- Describe how it started.
Determine whether the fault is continuous or intermittent and if there was a supply interruption or a recent intervention. If it reappears after a reset allowed by the user manual, do not chain resets.
Do not open the casing or manipulate gas, wiring, combustion, or flue gas outlet. If you smell gas, avoid flames and switches, leave the area, and notify the distributor's emergency service from a safe location; in case of immediate danger, call 112.
Saunier Duval Thema Condens 25-A components Manufacturer's diagram
Documented codes table
The meaning of the warning is provided, not the repair operations reserved for qualified personnel. When the manufacturer groups several codes, the grouping is maintained; it is not interpreted as a range of numbers.
| Code | What does it indicate? |
|---|---|
| F.00 | Interruption of the inlet temperature sensor |
| F.01 | Return temperature sensor interruption |
| F.10 | Short circuit in the inlet temperature sensor. |
| F.11 | Short circuit in the return temperature sensor |
| F.13 | Short circuit of the accumulator sensor |
| F.20 | Safety shutdown: temperature limiter |
| F.22 | Safety shutdown: lack of water |
| F.23 | Safety shutdown: excessive temperature variation |
| F.24 | Safety shutdown: temperature rise too fast |
| F.26 | Fault: gas valve not functioning |
| F.27 | Safety shutdown: incorrect flame detection |
| F.28 | Start-up fault: ignition failed |
| F.29 | Operating fault: failed ignition attempts |
| F.32 | Fault: fan |
| F.42 | Resistance fault coding (probably in combination with F.70) |
| F.49 | Fault: eBUS |
| F.52 | Fault in the connection of the circulating flow sensor |
| F.53 | Fault in the circulating flow sensor |
| F.54 | Gas pressure fault (in combination with F.28/F.29) |
| F.56 | Fault in the regulation of the circulating flow sensor |
| F.57 | Fault during comfortable safety operation |
| F.61 | Gas valve control fault |
| F.62 | Gas valve fault. Disconnection delay |
| F.63 | EEPROM fault |
| F.64 | Electronic fault / NTC |
| F.65 | Fault: PCB temperature |
| F.67 | Fault: electronics/flame |
| F.68 | Flame signal fault (unstable) |
| F.70 | Invalid product code (DSN) |
| F.71 | Fault of the heating flow temperature sensor |
| F.72 | Fault in the inlet and return temperature sensors. |
| F.73 | Water pressure sensor signal out of range (too low) |
| F.74 | Water pressure sensor signal out of range (too low) |
| F.77 | Fault in flue gas damper/condensate pump |
| F.79 | Accumulator temperature sensor fault |
| F.83 | Fault: temperature adjustment in the supply and/or return temperature sensors |
| F.84 | Fault: temperature sensor difference between supply/return, not plausible. |
| F.85 | Fault: incorrect installation of the inlet or return temperature sensor |
| F.86 | Fault: floor contact |
No matches found. Please check the code and the version of the equipment.
Is there a problem, but no fault code appears?
The absence of a warning does not rule out a fault. For a boiler that does not heat, does not deliver hot water, loses pressure, or operates intermittently, describe the symptom and the moment it occurs. Do not assume that the PCB, the pump, or a sensor is faulty without checking the equipment and the installation.
Request a review of the boiler. · Consult maintenance
Before requesting a repair
Does the code identify the spare part I need to buy?
No. A single warning can have multiple causes. The spare part reference requires identifying the appliance and confirming the fault; the code or a generic photograph is not sufficient.
Can it be reset again if the fault returns?
It is not advisable to chain resets. Follow only what is outlined for the user in your version's manual. A persistent or recurring lockout requires inspection.
When does it make sense to compare a new boiler?
When you have a diagnosis and a budget, compare repair, availability of the spare part, and replacement according to your installation. An isolated fault code does not justify changing the equipment.
Models of this guide in the catalog
See new boilers · Consult installation or replacement
The technical sheet of each product provides information on its price and availability. Installation is quoted separately depending on the case.
Does the warning still appear on your Saunier Duval boiler? Consult the Saunier Duval boiler technical service in Madrid or the spare parts and assistance for Saunier Duval.
Documentation and other guides
Consult fault guides by brand and model. · Return to the blog