Alarm codes
Complete TIS Tronic 260U alarm list with causes and resolutions — sensor errors, HUW overheating, lack of fuel, failed fire-up, emergency temperature and STB.
Alarms show on the main screen and pulse the red LED on the right of the front panel. Press F to open the alarm list, UP / DOWN to scroll, STOP to delete.
Full alarm list
| Alarm | Trigger | Resolution |
|---|---|---|
| Boiler temperature measurement error | T1 sensor missing or damaged | Check the sensor in the immersion well and the wiring at T1. Test the KTY-81-210 against the resistance table |
| HUW overheating | Hot water tank temperature exceeded 85 °C | Check the HUW pump on Q4, the T2 sensor position, the HUW setpoint and the temperature-increase value |
| Temperature measurement error, HUW | T2 sensor missing or damaged | Check the wiring at T2 and sensor continuity |
| Exhaust gas temperature measurement error | T3 sensor missing or damaged | Confirm the PT1000 is fitted and wired. Activating the sensor in the menu without fitting it produces this alarm |
| Lack of fuel | The quenching condition was met — by boiler temperature or by exhaust temperature | Reload. Then review fuel quality and the fuel shortage thresholds |
| Failed fireup | The firing-up time expired without the boiler rising above shutdown temperature + 2 °C | Check draft, fuel moisture, fan operation and minimum fan speed |
| Exceeding the boiler emergency temperature threshold | Boiler temperature exceeded 94 °C; the device switches to boiler protection mode | Check pumps, flow path, zone actuators, the bypass and the boiler cooling temperature setting |
| Overheating STB | External safety thermostat tripped (~90 °C water) | Boiler temperature must fall below 60 °C, then reset manually on the panel |
Clearing an alarm
Resolve the underlying cause. An alarm cleared without a fix returns immediately.
Press F to open the alarm list.
Scroll with UP / DOWN.
Press STOP to delete the error.
STB is different
An STB overheating alarm cannot be cleared until the boiler water temperature has fallen below 60 °C. This is required by PN-EN 303-5:2012 and is deliberate — it stops the fan restarting into a boiler that is still dangerously hot.
Alarms by urgency
| Urgency | Alarms |
|---|---|
| Stop and investigate now | Exceeding the boiler emergency temperature threshold · Overheating STB · HUW overheating |
| Fix before the next burn | Boiler temperature measurement error · Exhaust gas temperature measurement error · Failed fireup |
| Routine | Lack of fuel · Temperature measurement error HUW (if hot water is not in use) |
The temperature ladder
Knowing where each threshold sits makes most alarms self-explanatory:
| Temperature | What happens |
|---|---|
| 35 °C / 95 °F | Pumps start (pump start temperature) |
| 35 °C / 95 °F | Below this, boiler goes to STOP (boiler shutdown temperature) |
| 65 °C / 149 °F | Setpoint — boiler enters supervision |
| 78 °C / 172 °F | All circulation pumps forced on (boiler cooling temperature) |
| 80 °C / 176 °F | External controls ignored, fan control disabled (maximum boiler temperature) |
| 85 °C | HUW overheating alarm threshold |
| ~90 °C | STB cuts the fan (hardware) |
| 94 °C | Emergency threshold alarm, boiler protection mode |
The original PDF manuals this documentation was built from.
Common problems
Symptom-first troubleshooting for the UNI 60 — blank controller screen, fan humming but not turning, STB overheating, poor draft, failed fire-up and low output.
Downloads
Download the original MBtek UNI PDF manuals — boiler manual, install guide, TIS Tronic 260U controller manual, controller replacement guide and the specification sheet.