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Best Smart Thermostat for a Flat with Electric Underfloor Heating
A flat with electric underfloor heating has a specific control problem: the slab warms slowly, holds heat for hours, and wastes money if the thermostat reads only the air. The best smart thermostat for a flat with electric underfloor heating therefore needs floor sensing, app scheduling and a load rating that matches an electric mat rather than a boiler. The five picks below cover three buyer profiles: the budget renter who wants app control, the renovator fitting a touchscreen with floor and air sensing, and the smart-home user who wants HomeKit, Alexa and Google in one unit. The overview table shows the differences at a glance before the individual reviews.
The Picks at a Glance
| Product | Key Spec | Best Use | Price Tier |
|---|---|---|---|
| meross Matter Smart Thermostat | 120-240V, Matter, HomeKit/Alexa/Google/SmartThings | Budget smart control for baseboard and mat heating | Budget |
| SunTouch SunStat ConnectPlus | 4.3" touchscreen, floor and air sensing, Watts Home app | Floor-sensing control with energy monitoring | Mid |
| 6iE Smart WiFi Thermostat | Ultra-thin, SmartGeo, app control | Design-led flats with smartphone control | Mid |
| SunTouch CommandPLUS SunStat | Universal Wi-Fi, floor sensor included, 120V/240V | Straightforward programmable floor heating | Mid |
| Mysa Smart Thermostat LITE | 120V-240V, 7-day scheduling, HomeKit/Alexa/Google | Line-voltage baseboard and mat heating on a budget | Budget |
1. meross Matter Smart Thermostat
Voltage: 120-240V
Protocol: Matter
Voice assistants: HomeKit, Alexa, Google Home, SmartThings
Control: Wi-Fi remote control
Function: Programmable, energy saving
Type: Line-voltage thermostat for electric heaters
This is a line-voltage unit built for electric resistance heating, which is exactly the load an electric underfloor mat presents. The Matter badge matters here: it lets the thermostat join an existing smart home without a proprietary hub, and the four-assistant support covers almost every flat. Programming and remote control come through the app, so a heating schedule can be set from the sofa or from work. The build is the plain, functional plastic typical of budget smart thermostats, and the priority is compatibility rather than styling.
It earns its place as the budget entry because it covers the smart essentials at the lowest outlay. Buyers with a mixed smart home get one unit that speaks to everything, and the 120-240V range covers both common flat supplies. The trade-off is that this is a general electric heater thermostat rather than a dedicated floor unit, so a buyer who specifically wants floor-probe sensing should look at the SunTouch models instead.
2. SunTouch SunStat ConnectPlus Smart Wi-Fi Floor Heating Thermostat
Display: 4.3 inch touchscreen
Sensing: Floor and air
App: Watts Home
Voice assistants: Alexa, Google
Function: Energy monitoring, remote access
Type: Smart Wi-Fi floor heating thermostat
This is the pick that was designed for the job. Floor and air sensing means the thermostat can regulate by slab temperature rather than room air, which is the correct strategy for slow-reacting electric underfloor heating. The 4.3-inch touchscreen is large enough to read at a glance, and the Watts Home app adds remote access and energy monitoring so a flat owner can see what the mat is actually costing. Alexa and Google compatibility covers the common voice setups.
It suits the renovator or the buyer replacing an old dial stat who wants proper floor control and consumption data. The trade-off is the price tier: this is a mid-range unit, and the large touchscreen and monitoring features push it above the budget picks for a buyer who only needs a schedule.
3. 6iE Smart WiFi Thermostat for Underfloor Heating
Design: Ultra-thin
Display: Smartphone-style touchscreen
Control: App control
Feature: SmartGeo technology
Function: Energy-saving scheduling
Type: Smart Wi-Fi underfloor heating thermostat
The 6iE is the design-led option. The ultra-thin body and smartphone-style touchscreen suit a flat where the thermostat sits on a visible wall rather than in a cupboard. SmartGeo is a geofencing feature: the thermostat uses location to scale back heating when the flat is empty and bring it back before arrival, which is a sensible fit for underfloor heating’s long warm-up. App control handles scheduling and energy-saving adjustments.
It suits the buyer who cares how the wall looks and wants location-based automation rather than a plain schedule. The trade-off is that the thin form factor and geofencing features come from a small brand, so a buyer who wants the widest support ecosystem and the simplest possible setup may prefer a mainstream unit.
4. SunTouch CommandPLUS Floor Heating Thermostat SunStat
Voltage: 120V/240V
Display: Touchscreen
Sensor: Floor sensor included
Connectivity: Wi-Fi
Function: Programmable
Type: Universal floor heating thermostat
This is the practical, no-fuss floor heating thermostat. The floor sensor is included in the box, which removes a common extra purchase and a common source of installation confusion. The universal 120V/240V rating covers both flat supplies, and the touchscreen and Wi-Fi programming give app scheduling without the extra cost of a monitoring platform. It is a SunTouch unit, so it belongs to the same family as the ConnectPlus and shares the floor-heating focus.
It suits the buyer who wants a straightforward programmable floor thermostat with the sensor in the box and no steep learning curve. The trade-off is that it is the plainer sibling: a buyer who wants energy monitoring or a large display should step up to the ConnectPlus, while this model keeps the feature set lean.
5. Mysa Smart Thermostat LITE for Electric Baseboard Heaters
Voltage: 120V-240V
Scheduling: 7-day
Voice assistants: HomeKit, Alexa, Google
Connectivity: Wi-Fi
Function: Programmable, energy saving
Type: Line-voltage thermostat for electric baseboard heaters
Mysa built its name on line-voltage smart thermostats, and the LITE is the pared-back version. The 7-day scheduling gives a full week of independent programs, which suits a flat with a regular routine and a mat that needs a long pre-heat. HomeKit, Alexa and Google are all supported, so it slots into any of the three main ecosystems, and the 120V-240V rating covers standard flat wiring. The brand’s energy-saving claim is its headline pitch.
It suits the buyer who wants a proven line-voltage smart thermostat with strong voice support and simple scheduling. The trade-off is that this is a baseboard-focused LITE model: buyers who specifically want floor-probe sensing and floor-temperature regulation should choose a SunTouch unit, because the LITE’s strength is scheduling rather than slab control.
Before You Buy
- Sensing: Confirm whether the thermostat reads air only or supports a floor probe; electric underfloor heating performs far better with floor sensing.
- Voltage: Check the flat’s supply and match it to a 120V or 120V-240V rated unit before ordering.
- Load rating: Verify the thermostat’s switching capacity covers the total wattage of the heating mat, not just one zone.
- Compatibility: Check the chosen ecosystem — Matter, HomeKit, Alexa, Google or SmartThings — against the devices already in the flat.
- Sensor inclusion: Some units ship with a floor sensor and some do not; confirm what is in the box to avoid a second purchase.
- App and account: A Wi-Fi thermostat needs a stable network and a manufacturer account; check the app is available in the buyer’s region.
- Mounting depth: A flat wall box has limited depth, so check the thermostat’s rear clearance before committing.
Frequently Asked Questions
-
Does a smart thermostat work with electric underfloor heating?
Yes, provided it is a line-voltage thermostat rated for the mat’s wattage. A dedicated floor-sensing model gives the best control. -
Is floor sensing better than air sensing for underfloor heating?
Generally yes. The slab reacts slowly, so regulating by floor temperature avoids overshooting and long wasteful warm-up cycles. -
Can these thermostats be controlled from a phone?
All five picks offer Wi-Fi app control, and four also support voice assistants for hands-free adjustment. -
Does a flat need a special voltage thermostat?
No special type, but the unit must match the flat’s supply. The picks here cover 120V and 120V-240V installations. -
Will a smart thermostat reduce heating bills?
Scheduling, geofencing and floor sensing all cut wasted run time. Savings depend on the flat’s insulation, tariff and routine. -
Can a renter install one?
Only with the landlord’s agreement, since it is a fixed wiring change. A qualified electrician should handle the swap.
Bottom Line
For a flat with electric underfloor heating, the SunTouch SunStat ConnectPlus is the strongest all-round choice: floor and air sensing, a readable touchscreen, energy monitoring and app control in one unit. Buyers on a tighter budget can take the meross Matter model for smart control, while the Mysa LITE suits anyone prioritising scheduling and voice support over slab sensing.
