Quenching and fuel shortage
How the TIS Tronic 260U detects that the fire is out — by boiler temperature or exhaust gas temperature — and what it does with the fan and the central heating pump.
The controller detects a dead fire one of two ways — falling water temperature, or falling exhaust gas temperature — and the exhaust method is considerably more responsive. Choose the method in Boiler settings → Fuel shortage detection method.
Default behaviour without an exhaust sensor
As standard, without a connected exhaust gas temperature sensor, boiler quenching (switching off) is based on the boiler temperature. The choice of method only appears once a PT1000 is connected.
Method 1 — boiler temperature
The boiler switches to quenching mode when the water temperature falls to the boiler shutdown temperature.
| Parameter | Range | Default | MBtek value |
|---|---|---|---|
| Boiler shutdown temperature | 30–45 °C | 35 °C | 35 °C / 95 °F |
When it triggers:
- the controller turns off the fan;
- the START diode on the front panel turns off;
- the STOP diode lights up.
Method 2 — exhaust gas temperature
The boiler switches to quenching when the exhaust gas temperature falls below a set threshold and stays there for a set time.
| Parameter | Range | What it does |
|---|---|---|
| Exhaust gas temperature, fuel shortage detection threshold | 30–90 °C | The exhaust temperature below which the boiler will switch to extinguishing mode |
| Fuel shortage detection time | 2–200 min | The delay — how long the exhaust temperature must fall or stay below the threshold before the controller acts |
When it triggers, the controller turns off the fan, the START diode turns off and the STOP diode lights up — the same as method 1.
Why the delay matters
Exhaust temperature dips briefly every time you open a door or the fire settles. The detection time stops those dips being mistaken for a dead fire.
Pump behaviour during quenching
Two settings decide what happens to the central heating pump when the fire goes out.
| Parameter | Range | Effect |
|---|---|---|
| Fuel shortage CH pump OFF | YES / NO | Whether the CH pump is switched off during extinguishing mode |
| CH pump shutdown delay | 5–120 min | How long after entering extinguishing mode the pump stops. Requires the setting above to be YES |
Leave the pump running if the boiler still holds useful heat. The boiler's 40 gallons of water are worth circulating into the system rather than letting them sit.
The related alarm
| Alarm | Meaning |
|---|---|
| Lack of fuel | The quenching condition above has been met |
| Failed fireup | The time specified in the firing-up time function expired without the boiler temperature rising above shutdown temperature + 2 °C |
See Alarms for the full list and how to clear them.
NextAlarmsEvery alarm the controller can raise, and what each one means.
Room thermostat control
How the TIS Tronic 260U uses a room thermostat on I2 — pump cycling once the room is satisfied, operating and pause times, and the overheat override.
Alarms
Every TIS Tronic 260U alarm — sensor errors, HUW overheating, lack of fuel, failed fire-up, emergency temperature and STB overheating — with causes and how to clear them.