PIERRE T2 - Dry Contact Thermostat (24V, White)

Wired. Needs a PIERRE Pro Controller plus a Modbus (TTL to RS-485) converter.

Versions

The PIERRE T2 thermostat is made in two communication versions and two supply voltages. This manual covers the Modbus RTU version for PIERRE Pro installations; a Zigbee version exists for PIERRE Wave installations. Each version is supplied for either 24 V or 230 V AC (L, N). The version must match the communication method and the supply voltage of the installation, and a thermostat must only be connected to the supply voltage it is rated for.

Local and integrated operation

The T2 works as a room thermostat on its own: the user sets the temperature at the thermostat and its relay output switches the heating or cooling circuit. Once it is connected to the PIERRE system over Modbus RTU or Zigbee, its temperature, set point and mode become available for central control, the Smart PIERRE app, PIERRE displays, scenes, schedules and automations. Local operation keeps working when the connection is down.

PIERRE Pro – Modbus RTU

The Modbus version connects by wire: T2 thermostat → Modbus RTU (A+, B−) → TTL to RS-485 converter → PIERRE Pro Controller. Several thermostats share one bus; each needs its own Modbus address (function 14) and the same baud rate (function 15). The bus is a shielded twisted pair, terminated at both ends. Wiring details are in the Wiring section.

PIERRE Wave – Zigbee

The Zigbee version needs no communication cable: T2 thermostat → Zigbee → a PIERRE display and/or gateway → PIERRE system. It is powered from its 24 V or 230 V supply and paired with the gateway from the Smart PIERRE app. Zigbee range is reduced by distance, reinforced-concrete walls and floors; where coverage is weak, use Zigbee repeaters or additional gateways, and plan the gateway positions during system design in large or multi-storey buildings.

Controlling the heating or cooling circuit

Two arrangements are possible:

1. From the thermostat relay. The T2 switches the valve actuator or the control input of the heating/cooling device through its own output and regulates the room locally, while the PIERRE system monitors and adjusts it over the bus or Zigbee.
2. From the PIERRE Pro Controller (Modbus version). The T2 supplies the room temperature and set point over Modbus RTU; the Pro Controller switches the circuit from its own output through a relay, for example a 230 V thermoelectric valve actuator. This suits installations where all heating and cooling zones are wired centrally to the distribution board.

1. Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.
2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.
3. Installer must be a trained, experienced service technician.
4. After installation is complete, check the product operation as described in these instructions.

PIERRE T2 Modbus thermostat — underfloor heating / ceiling cooling

Controller to converter is four conductors: 12 V, GND and the two TTL data lines. The 24 V supply reaches the thermostat on two conductors. The Modbus bus itself is a two-conductor pair, A+ and B−: use shielded twisted pair in a bus topology, terminated at both ends of the line.

The 24 V supply and the Modbus bus may also share one shielded 4-core cable: two conductors for 24 V and GND, two for A+ and B−.

PIERRE T2 Modbus thermostat — wiring diagram

PIERRE T2 Modbus thermostat — wiring example

This Thermostat is suitable for installation within a standard 86 mm or European 60 mm wall box.

During Power On

1. Power On/off:

Press the Center Knob to turn the thermostat on/off.

2. Manual & Programmable

Press the Mode button to change between manual mode (🔥) and programme mode (🕒).

• In manual mode, 🔥 will show on the display.
• In programmable mode, 🕒 will show on the display.

3. Setting Temperature

In the programming mode, the temperature setting and time setting will be locked. To adjust them, first switch the thermostat to manual mode by pressing the Mode button.

In the manual mode, the desired temperature can be set by turning the Center Knob.

4. Adjusting/Setting the Clock

Press 🕒 to set minute, hour and weekday, and adjust the values by turning the Center Knob.

Press the Mode button once more to confirm and exit.

5. Locking your Thermostat

Press and hold the Mode button and 🕒 for 5 seconds to lock/unlock your thermostat.

Full lock or partial lock is selected with function 4 (Button locking) in the function settings (see 8).

6. Adjusting/Setting the Programmable Schedules

Press icon 🕒 four times in a row. You can see "MON TUE WED THU FRI" and the minutes of time are flashing.

• Turn the Center Knob to set the minutes.
• Press the icon 🕒 again; the hour of the time will flash, set the hour by turning the Center Knob.
• Press the icon 🕒 again; the temperature setting will flash, set the temperature by turning the Center Knob.

This completes the setting of Period 1.

In the same way, complete the settings of the remaining periods.

Press the icon 🕒 once more to enter the Saturday schedule settings (you will see the SAT on the screen).

Repeat the above process to set the period and temperature, and Sunday schedule.

Press the icon 🕒 once more to confirm and exit.

A separate schedule may be set for weekdays (Mon–Fri) and for weekends (Sat and Sun).

7. Checking the Temperature of Floor Sensor

Press and hold the 🕒 button for 5 seconds to display the temperature of the floor sensor.

If no external sensor is connected, the thermostat will display "Er".

⚠ Note: Do not use third-party external sensors; the temperature will be incorrect.

8. Setting the Functions and Options

During power off, press and hold the Mode button and 🕒 for 8 seconds in order to reach system function.

Then press the Mode button to scroll through the available functions, and turn the Center Knob to change the available options.

All settings are confirmed automatically.