Vaillant Boiler Symbols
Shown below are the symbols and meanings for the newer generation of Vaillant boilers as well as some older models. These symbols are mostly found on the ecotec series of boilers. If anything is not clear, please feel free to let us know.
| MBNo | Symbol | Description and Explanation | Models Applicable to: | ||
|---|---|---|---|---|---|
| 1 |  | Flame: Permanently on: Correct burner operation; Burner on | New Ecotec | ||
| 2 |  | Display of the current burner modulation rate (bar graph display) | The bar graph will go up and down depending on the power level the boiler is firing at. | New Ecotec | Article |
| 3 |  | Flame: Permanently on: Correct burner operation; Burner on | Older Ecotec | ||
| 4 |  | Flame with cross: Boiler is at lock out and will display fault code | Older Ecotec | Article | |
| 5 |  | Display of the current filling pressure of the heating system (bar graph display). The filling pressure must be in the mid range between the two dotted lines. | - Permanently on: The filling pressure is within the permitted range. - Flashing: The filling pressure is outside of the permitted range | Article | |
| 6 |  | Heating mode active | - Permanently on: Heat demand, heating mode | Article | |
| 6.1 | | Heating mode active | - Flashing: Burner on in heating mode | Article | |
| 7 |  | Hot water generation active | - Permanently on: In draw-off mode before burner is on - Flashing: Burner on in draw-off mode | Article | |
| 7.1 | | Hot water generation active | - Flashing: Burner on in draw-off mode | Article | |
| 8 |  | Hot water generation active | For VUI (Storage Combination) / VUW (Combination) boilers: - Permanently on, burner is on:Â In draw-off mode before the | Article | |
| 8.1 | | Hot water generation active | - Flashing:Â Burner on in draw-off mode | Article | |
| 9 | | Hot water generation active | On VU (System / OpenVent) boilers: - Permanently on:time slot activated for hot water generation | Article | |
| 9.1 | | Hot water generation active | - Flashing:Â Domestic hot water cylinder is being heated, burner on | Article | |
| 10 |  | Maintenance / Service required. | In the "Live monitor", you can read further information about the reason for the service (¬ Section 8.2). | Article | |
| 11 |  | Summer mode active Heating mode is switched off | Decrease the heating flow temp until it says off. Increase the flow temp to original value to turn heating back on. | Article / Video | |
| 12 |  | Boiler anti-cycling time is active | This function is used to prevent frequent on/off operations, and therefore contributes to prolonging the life of your boiler. The symbol also appears if the boiler is in a waiting period. | Article | |
| 13 |  | Internal pump is running | |||
| 14 |  | Gas valve is activated | |||
| 15 |  | F.XX Fault in the boiler. | Appears instead of the basic dis-play (¬ Section 4.4). A plain text display explains the displayed fault code. Example: F.10 Flow NTC short circuit. | Article / Page |