Where does the boiler temperature sensor go?

The CH sensor for central heating is lowered into the immersion well on top of the boiler, followed by the thermal protection sensor (STB). Adding any liquid to the immersion well is forbidden. If no well is available, the CH sensor may be fitted to the supply branch pipe up to the connection nut and pressed with a metal clamp.

What does the STB do?

The STB is an independent bimetallic sensor that turns off the fan if the boiler water rises above about 90 °C, preventing the water from boiling. Per EN 303-5:2012 the fan cannot restart on its own — the water must fall below 60 °C and the alarm must be reset manually on the control panel.

Which terminal is the room thermostat?

Terminal I2, with a dry contact. If you are using a 24 VAC thermostat, use a 24 VAC SPDT relay.

Electrical and sensors

Wire the TIS Tronic 260U — 230 V supply, grounding, boiler sensor in the immersion well, STB safety thermostat on I1, and the optional PT1000 exhaust probe.

All electrical work on the UNI 60 must be done by a qualified electrician, and the boiler must be electrically grounded. The safety chain that protects the boiler from boiling is hardware, not software, so getting the STB right matters more than any controller setting.

Power off before any work

The device is under electric voltage. It is forbidden to work on connecting pumps, fans or other electrical devices while the regulator is connected to the power supply. Switch off the power and take measures against accidental switching on.

Before energising

Ground the boiler

Boilers TIS UNI must be electrically grounded.

Measure before you connect

Measure the ground resistance of the electric motors (pumps), and the insulation resistance of the electrical wires.

Fit a voltage stabiliser

For reliable and stable operation of the regulator, install a voltage stabiliser with an appropriate load rating.

Check the environment

The controller must not be exposed to liquids and must not be located in rooms with high humidity. Keep dirt and conductive dust out of it. Operating range: 5–40 °C, 30–75 % RH.

Terminal map

TIS Tronic 260U board layout showing the 230 V power input, PE terminals, fan output Q1, pump outputs Q3 and Q4, inputs I1 and I2, sensor terminals T1, T2, T3, the X23 alarm header and the TR2_DISP panel connector — **TIS Tronic 260U board view and connection diagram.** Source: TIS Tronic 260U manual §7.1.

Symbol	Designation
`Q1`	Fan outlet
`Q3`	Central heating pump outlet
`Q4`	Hot water (HUW) pump output
`I1`	Emergency thermostat STB
`I2`	Central heating room thermostat
`T1`	Boiler temperature sensor
`T2`	HUW temperature sensor
`T3`	Exhaust gas temperature sensor
`TR2_DISP`	Panel connector
`X23`	Additional alarm (optional)
`- + A B`	Alternative slot for additional modules

Power comes in at 230 V on L and N, with PE earth terminals on the board.

Sensor placement

Diagram showing the T1 boiler sensor lowered into the immersion well on the boiler top plate, with the STB or DZT thermal protection sensor mounted beside it — **Sensor placement.** T1 (boiler sensor) goes down into the immersion well; the STB/DZT thermal protection sensor sits on the same well. Source: UNI Install Guide, page 2.

The CH sensor is lowered into the immersion well, followed by the thermal protection sensor (STB).

No liquid in the well

Adding any liquid to the immersion well is forbidden — no oil, no water, no paste. The sensor should be installed in a dry place.

If there is no immersion well, it is permitted to install the CH sensor on the supply branch pipe — up to the connection nut — and press it against the pipe with a metal clamp.

Sensor schedule

Sensor	Terminal	Wire length	Type
CH sensor (boiler)	`T1`	0.8 m	KTY-81-210
HUW (hot water tank)	`T2`	3 m	KTY-81-210
Exhaust gases	`T3`	—	PT1000
STB	`I1`	1 m	Bimetal

Sensors have no polarity — wiring sequence is not significant.

The exhaust sensor is not included

The PT1000 exhaust gas sensor is not supplied in the regulator standard kit. It is required for Brager Expert exhaust gases mode, which is the mode MBtek recommends for the UNI 60.

The STB safety chain

Recommended hydraulic diagram showing the boiler with fan, STB and CH sensor, central heating pump, thermostatic three-way valve, check valves, heating system radiators, HUW pump and water tank, with a detail of the sensor immersion well — **STB connection options and the recommended hydraulic circuit.** Note the detail panel: the CH sensor goes into the immersion well first, then the STB. The diagram is approximate and simplified. Source: TIS Tronic 260U manual §7.3.

An independent bimetallic sensor turns off the fan if the water temperature in the boiler rises above 90 °C, preventing the water from boiling in the event of boiler overheating.

In accordance with PN-EN 303-5:2012, when the water temperature drops back to a safe value it is not possible for the fan to turn itself on again. The fan can only restart after:

the water temperature in the boiler drops below 60 °C, and
the error is manually reset on the control panel.

The protection sensor has two wires, connected to the I1 STB terminal. Polarity does not matter.

DZT thermal protection sensors

Sensor	Opens at	Closes at
DZT-1	185 °F / 85 °C	140 °F / 60 °C
DZT-2	200 °F / 95 °C	155 °F / 70 °C

Both connect to terminal I1. To operate at a higher temperature, order a DZT-2 from MBtek (Parts — UNI 15-40-60-95).

Replacing a sensor

Disconnect the power plug from the electrical outlet.

Unscrew the fixing screws on the back of the housing and remove the top cover.

Find the socket on the board using the terminal map above.

Press the connector with a flat screwdriver to release the fastening clip, then withdraw the wire.

Fit the new sensor. Correctly installed wires cannot be pulled out without pressing the terminal — if a wire slides free, it is not seated.

NextPump wiring

Connecting a 120 V circulator to the controller's 230 V outputs.