ENGO EONE-16W is a flush-mounted Wi-Fi smart thermostat with a built-in 16(2)A relay, engineered for underfloor heating and electric heating mats that draw higher current than a standard low-voltage sensor circuit can switch. Because the relay is rated to 16A, it can drive many electric heating mats directly without an external contactor, simplifying the installation and reducing the parts list on straightforward single-zone jobs. The thermostat combines Wi-Fi 2.4GHz and MODBUS RS-485 communication, giving installers a choice between app-based control via the ENGO Smart platform or integration into a wider building management system. Available in white.
16(2)A
Max. switching current
13mm
Depth after mounting
Wi-Fi + Modbus
Communication
Installation must be carried out by a qualified electrician
This thermostat switches mains voltage at up to 16(2)A. Installation must be performed by a person with appropriate electrical qualifications, in accordance with the wiring regulations in force in the country of installation (including BS 7671 in the UK). ENGO Controls accepts no responsibility for non-compliant installation.
Floor sensor strongly recommended for electric heating mats
When switching an electric heating mat, ENGO recommends fitting a floor temperature sensor to the S1-S2 input to provide overheating protection. The maximum load of 16(2)A must not be exceeded by the connected heating mat or actuator.
Key Features
16A relay removes the need for a contactor
Most low-voltage UFH thermostats top out at 3A and require a separate contactor to switch an electric heating mat. The built-in 16(2)A relay in the EONE-16 handles that load directly, cutting an extra component and a wiring step out of straightforward single-zone electric UFH jobs.
TPI algorithm holds setpoint tightly
The TPI (Time Proportional and Integral) control algorithm pulses the relay on and off in short bursts rather than simple on/off switching, which keeps floor temperature closer to setpoint and reduces the temperature swing that a basic hysteresis thermostat would allow.
Works fully offline as well as via the app
Schedules are stored on the thermostat itself, so daily or weekly heating programmes keep running even if the home Wi-Fi network or internet connection drops out. Wi-Fi is only needed for remote access and initial setup via the ENGO Smart app.
S1-S2 input adapts to three different sensor roles
The same volt-free input can be configured as a floor sensor, an air sensor, or an occupancy sensor input (for example a hotel key-card switch), letting one hardware design cover several different installation scenarios via the installer parameters.
MODBUS RS-485 for BMS integration
Alongside Wi-Fi, the thermostat carries a MODBUS RS-485 port, making it suitable for installations that need to report into a building management system rather than (or as well as) a consumer smart-home app.
Ultra-slim 13mm finished depth
Once mounted into a standard 60mm flush electrical box, the visible depth of the thermostat is just 13mm, keeping the finished fascia close to the wall for a discreet, modern appearance.
Technical Specification
| Power & Switching |
| Power supply |
230V AC, 50Hz |
| Max. switching current |
16(2)A |
| Control output |
SL, 230V AC |
| Temperature Control |
| Setpoint range |
5.0°C to 45.0°C |
| Display accuracy |
0.5°C |
| Control algorithm |
TPI, or hysteresis (±0.2°C to ±2.0°C) |
| Connectivity |
| Communication |
Wi-Fi 2.4GHz, MODBUS RS-485 |
| S1-S2 input |
Floor sensor / air sensor / occupancy sensor (NTC 10/12/15kΩ) |
| Control input |
CO/NSB, 230V AC (heat/cool changeover or night setback) |
| App platform |
ENGO Smart (powered by Tuya) |
| Physical |
| Dimensions |
90 x 90 x 37mm (13mm after flush mounting in a Ø60 box) |
| Mounting |
Flush-mounted, standard 60mm electrical box |
| Colour |
white |
| Compliance |
| EU directives |
2014/53/EU, 2011/65/EU |
Frequently Asked Questions
Do I need a floor sensor with this thermostat?
A floor sensor connected to the S1-S2 input is recommended when the EONE-16 is switching an electric heating mat, as it provides overheating protection that a room-only sensor cannot.
Can the EONE-16 switch an electric heating mat directly, without a contactor?
In most cases, yes. The internal relay is rated to 16(2)A, which covers many electric heating mat circuits without an external contactor, provided the mat's load does not exceed this rating.
Will the thermostat keep working if my Wi-Fi goes down?
Yes. Time schedules are stored locally on the thermostat and continue to run in offline mode. Wi-Fi is only required for remote control and setup through the ENGO Smart app.
Can this thermostat control heating and cooling?
Yes, via the CO input, which can be configured for automatic heating/cooling changeover or, alternatively, for a night setback (NSB) function.
Does this thermostat need a separate gateway or hub?
No gateway is required for basic Wi-Fi and app operation. The MODBUS RS-485 port is available for installers who want to integrate the thermostat into a wider building management system.
