Product description

Smart room temperature and humidity sensor-controller | 0…50°C | 0-95%rH | 0-10VDC/0-20mA/PWM | Modbus RTU | 18-34VDC/15-24VAC | IP30 | Sentera Controls | RCTHG-2

The RCTHG-2 is a Sentera Controls smart room temperature and humidity sensor-controller: it measures temperature (0…+50 °C) and relative humidity (0–95 % rH) in a room and, using the integrated algorithm, generates a single analog / modulating output (0-10 VDC, 0-20 mA or PWM) that can directly control an EC fan, an AC fan speed controller or a damper actuator. Power supply – 18–34 VDC or 15–24 VAC ±10 %; all parameters are accessible via Modbus RTU.

Key idea:
This is a transmitter and a controller in one: it needs no separate controller, because the output is calculated in the sensor itself according to the set temperature and humidity ranges. The output is determined by the higher of the two values, and either parameter can be disabled – e.g. to control by temperature only or by humidity only.

Measurement
0…+50 °C / 0–95 % rH

Control output
0-10 VDC / 0-20 mA / PWM

Power supply
18–34 VDC or 15–24 VAC ±10 %

Protection
IP30, indoors only

Operating principle

The sensor is fixed to a wall in the room (2 holes of Ø 6 mm) and wired with 3 wires with a common ground: supply 18–34 VDC or 15–24 VAC (VIN, GND), control output AO1 and Modbus RTU (A, /B).

Integrated sensors measure temperature and relative humidity; a range is set for each quantity within which the output varies 0–100 %, the output is determined by the higher of the two calculated values, and either quantity can be disabled. The output type is selectable – 0-10 VDC (≥ 50 kΩ), 0-20 mA (≤ 500 Ω) or 1 kHz PWM (open collector, 3.3 or 12 VDC) – and it directly controls an EC fan, an AC fan speed controller or a damper actuator; all parameters are changed over Modbus RTU, and the firmware is updated over the network.

Result – demand-controlled ventilation without a separate controller: as humidity or temperature rises the fan speeds up, and when it falls it slows down to the minimum, while the three-colour LED and light sensor inform the user on site.

Benefits RCTHG-2?
Sensor and control algorithm in one – less equipment in the control panel, a simpler design and faster commissioning, while Modbus RTU allows later integration into a BMS.

Technical specifications

Product type	Smart room temperature and humidity sensor-controller
Manufacturer / code	Sentera Controls / RCTHG-2
Series	RCTH-2 (RCTHF-2 / RCTHG-2 / RCTHH-2)
Measured quantities	Temperature, relative humidity, ambient illuminance
Temperature range	0…+50 °C
Humidity range	0–95 % rH, non-condensing
Accuracy	±0.4 °C (0…+50 °C); ±3 % rH
Control logic	Output based on the higher of the T and rH values; each parameter can be disabled
Analog output	1 × 0-10 VDC (RL ≥ 50 kΩ) / 0-20 mA (RL ≤ 500 Ω) / PWM 1 kHz, open collector, 3.3 or 12 VDC
Communication	Modbus RTU (RS485), A, /B; firmware update via Modbus RTU
Supply voltage	18–34 VDC or 15–24 VAC ±10 %
Connection	3-wire, common ground (-G)
Indication	Red / yellow / green LED, ambient light sensor
Installation	On a wall, 2 holes Ø 6 mm
Protection class	IP30 (EN 60529), indoor use only
Compliance	LVD 2014/35/EU, EMC 2014/30/EU, WEEE 2012/19/EU, RoHS 2011/65/EU

Manufacturer documentation

✔ Recommended by Elektrotechnikos sprendimai

Original manufacturer documentation – technical data, wiring diagrams and installation instructions.

Main functions

Integrated control algorithm – the output is generated according to the set T and rH ranges, without a separate controller.
Parameters that can be disabled – can be controlled by temperature only or humidity only.
Direct control – An EC fan, AC speed controller or damper actuator is connected directly to the output.
Modbus RTU – all parameters and measurements are accessible remotely; Modbus timeout (HR8) monitoring.
Firmware update – over the Modbus RTU network.
LED indication – red – value out of range or sensor fault, yellow – danger zone or Modbus connection lost, green – normal.
Light sensor – adjustable “active” and “standby” illumination levels – e.g. for quieter operation at night.
Configuration – Configuration and monitoring – the free Sentera 3SModbus software (via the CNVT-USB-RS485 converter) or the Sensistant Modbus configurator.

Where is it used?

Bathrooms, showers, laundries
Offices, classrooms, residential rooms
Warehouses and archives
Systems with EC fans or dampers
BMS with Modbus RTU
Washers and dryers with an AC fan speed controller
Residential buildings with 24 VAC ventilation automation

On-demand operation

For the residential building ventilation installer.
The -G version is powered from a 24 VAC transformer or 24 VDC and wired with 3 wires.

For the modernizer of AC fan systems.
The output connects to the analog input of an AC fan speed controller, and ventilation becomes demand-controlled.

For laundry and utility room owners.
The fan speeds up only when humidity rises, so there is less noise and energy consumption.

Practical application

If in a laundry the AC fan is controlled by a speed controller with a 0-10 VDC input and the supply is 24 VAC, then the RCTHG-2 is wired with 3 wires and proportionally increases the fan speed when humidity rises above the start of the set range.

Application guide: how it is used in practice

The same RCTHG-2 adapts to different sites – only what is connected to its output changes:

Site	What is connected	Result	Installer's note
Bathroom, shower, laundry	AO1 0-10 VDC → EC fan control input	As humidity rises, extraction automatically increases; when it falls, it returns to the minimum	Temperature can be disabled – control by rH only
Warehouse, workshops	AO1 → AC fan speed controller analog input	On a hot day extraction increases with temperature	Select the signal type according to the regulator input
System with an air damper	AO1 → damper actuator 0-10 VDC input	The damper opens in proportion to humidity or temperature	Check the actuator input resistance (≥ 50 kΩ for voltage mode)
Building with BMS	Modbus RTU → A, /B	Settings and status are accessible centrally	A separate address for each sensor

How to choose a room temperature and humidity transmitter

Installation / output / power supply	Recommended model
Wall, 3 analog outputs, 18–34 VDC, 4-wire	RSTHF-3 (room transmitter, -F)
Wall, 3 analog outputs, 18–34 VDC or 15–24 VAC, 3-wire	RSTHG-3 (room transmitter, -G)
Wall, Modbus RTU only, PoM, RJ45	RSTHM-2 (room Modbus sensor)
Wall, Modbus RTU + wall surface temperature (dew point control), PoM	RWTHM-2 (with surface temperature sensor)
Wall, direct control with 1 output, 18–34 VDC	RCTHF-2 (smart room, -F)
Wall, direct control with 1 output, 18–34 VDC or 15–24 VAC	RCTHG-2 (smart room, -G) ← this model
Wall, direct control with 1 output, 24 VDC via RJ45 (PoM) or terminals	RCTHH-2 (smart room, PoM)
Flush-mounted / surface-mounted, 1 output, powered directly from the 230 V mains	FCTH8 (85–264 VAC)
Flush-mounted / surface-mounted, 1 output, 18–34 VDC	FCTHF (-F)
Flush-mounted / surface-mounted, 1 output, 18–34 VDC or 15–24 VAC	FCTHG (-G)

Rule: first decide where the measurement is made (duct, room, outdoors), then what you need from the transmitter: separate analog signals for a controller (transmitter, 3 outputs), data only to a BMS (Modbus / PoM version), or direct fan control with a single output (smart sensor). Finally – the supply and number of wires: -F – 24 VDC, 4-wire, separate grounds; -G – AC or DC, 3-wire, common ground; -M / -H – power over the Modbus cable (RJ45).

When to choose another solution: for measurement only with 3 outputs – RSTHF-3 / RSTHG-3; for flush mounting – FCTH series; when CO2 is also needed – RCMF-3 series.

Pros

Transmitter and controller in one
Control by T, rH or both
Accuracy ±0.4 °C, ±3 % rH
Modbus RTU, firmware updated over the network
0-10 VDC / 0-20 mA / PWM output
LED indication and light sensor

Cons / limitations

One control output – for separate T and rH signals choose a transmitter (RSTH-3 / DSTH-3)
IP30 – dry rooms only
Must not be mixed with -F type products on the same network

Safety and installation notes

Installation and connection are to be carried out by a qualified electrician / automation specialist with the power disconnected.
Supply voltage – 18–34 VDC or 15–24 VAC ±10 %.
The -G version: 3-wire connection with a common ground (the analog output GND is connected to the supply GND). Never connect the common ground of the G version to devices powered by direct voltage (DC) – the connected devices may be damaged.
Do not mix -F and -G type products on the same network.
Resetting the Modbus communication parameters – with a jumper on PROG pins 1 and 2 for at least 5 s.
For indoor use only.

Quick selection guide

0…+50 °C

0–95 % rH

0-10 VDC / 0-20 mA / PWM

Modbus RTU

18–34 VDC / 15–24 VAC

IP30

Suitable when you need:

to control a fan or damper according to temperature and humidity in a room without a separate controller;
to implement demand-controlled ventilation in damp rooms;
to integrate the control into a BMS later via Modbus RTU.

Check before use:

the input type of the controlled device (0-10 VDC, 0-20 mA or PWM);
the supply: 18–34 VDC or 15–24 VAC ±10 %;
whether separate T and rH signals are needed – then choose a transmitter.

Important reminder: The RCTHG-2 generates a single control signal based on T and rH; it does not replace the power section of a fan speed controller.

FAQ

Is a separate controller required?
No, the algorithm is built in, and the output connects directly to an EC fan, AC speed controller or damper.

Can it be controlled by humidity only?
Yes, the temperature (or humidity) parameter can be switched off via Modbus RTU.

How are the settings changed?
Via Modbus RTU – the 3SModbus software with a CNVT-USB-RS485 converter, or via BMS.

How do I reset the Modbus settings?
With a jumper on PROG contacts 1 and 2 for at least 5 seconds.

What is the difference between the -F and -G versions?
-F is powered at 18–34 VDC and wired with 4 wires with separate grounds, while -G is powered at 18–34 VDC or 15–24 VAC and wired with 3 wires with a common ground.

Can it be powered with alternating current?
Yes, the -G version is powered with 15–24 VAC or 18–34 VDC.

Smart room temperature and humidity sensor-controller | 0…50°C | 0-95%rH | 0-10VDC/0-20mA/PWM | Modbus RTU | 18-34VDC/15-24VAC | IP30 | Sentera Controls | RCTHG-2

Sentera RCTHG-2 – smart room temperature and humidity sensor-controller: 0…+50 °C, 0–95 % rH, 0-10 VDC / 0-20 mA / PWM control output, 18–34 VDC or 15–24 VAC ±10 % supply, IP30. Humidity- and temperature-based ventilation without a separate controller.

Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

Attributes

Manufacturer

Sentera controls

CE certificate – a guarantee of safety, quality, and compliance

This product is marked with the CE label, which confirms that it complies with all applicable European Union directives and regulations. CE marking is not just a formality – it is an important indicator of quality and safety, ensuring that the product has been properly assessed, tested, and can be safely used throughout the EU market.

CE certification means that the product has been evaluated according to the main criteria:

Safety requirements – ensures that the product does not pose a risk to the user or the environment
Electromagnetic compatibility (EMC) – the device does not interfere with other equipment and is resistant to external disturbances
Environmental standards – complies with current ecological and material usage requirements
Operational reliability – the product is suitable for long-term use according to its intended purpose

CE marking allows this product to:

be legally supplied and used in all European Union countries
ensure a high level of quality and safety
be used in residential, commercial, and industrial environments

The CE mark is a declaration of the manufacturer’s responsibility, confirming that the product complies with all applicable standards and has been assessed according to EU legislation.

What does this mean for you as a buyer?

Safe use in everyday activities
Reliable performance and reduced risk of failure
Compliance with EU standards and requirements
Suitability for professional solutions

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Product Catalog

Smart room temperature and humidity sensor-controller | 0…50°C | 0-95%rH | 0-10VDC/0-20mA/PWM | Modbus RTU | 18-34VDC/15-24VAC | IP30 | Sentera Controls | RCTHG-2

Smart room temperature and humidity sensor-controller | 0…50°C | 0-95%rH | 0-10VDC/0-20mA/PWM | Modbus RTU | 18-34VDC/15-24VAC | IP30 | Sentera Controls | RCTHG-2

Operating principle

Technical specifications

Manufacturer documentation

Main functions

Where is it used?

On-demand operation

Practical application

Application guide: how it is used in practice

How to choose a room temperature and humidity transmitter

Pros

Cons / limitations

Safety and installation notes

Quick selection guide

FAQ

Smart room temperature and humidity sensor-controller | 0…50°C | 0-95%rH | 0-10VDC/0-20mA/PWM | Modbus RTU | 18-34VDC/15-24VAC | IP30 | Sentera Controls | RCTHG-2

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