7 Best Line Voltage WiFi Thermostats to Buy in 2026

The OJ Microline UWG4-4999 commands attention with its dual-voltage support (120V/240V), Class A GFCI protection, and adaptive self-learning programming—a rare trifecta in line voltage thermostats. Its 3.5-inch responsive touchscreen delivers a premium interface that simplifies complex radiant floor heating control, while the built-in floor and ambient temperature sensing ensures precise thermal regulation across tile, wood, or concrete. For homeowners tired of clunky, outdated thermostats, this model offers a seamless blend of safety, intelligence, and elegance—solving the all-too-common pain point of unreliable floor heat and inefficient energy use.

In real-world testing, the UWG4 shines in wet environments like bathrooms and basements, thanks to its C-UL-us Wet Room certification and GFCI fail-safes that prevent electrical hazards. It handles up to 3,600W at 240V, making it ideal for large radiant zones, and the power logging feature provides granular energy reports via app—something few competitors offer. However, its Wi-Fi connectivity can occasionally drop during router reboots, requiring manual reconnection. While it excels in floor heating precision, it lacks voice assistant integration, a missed opportunity in today’s smart home landscape.

Against the Mysa and MAXKOSKO models, the UWG4 positions itself as a high-end, safety-first choice for electric in-floor systems, trading voice control for industrial-grade reliability and energy analytics. It’s best suited for users prioritizing long-term durability, moisture resistance, and detailed energy tracking over flashy smart integrations. Though it lacks Alexa/Google compatibility, its adaptive learning and GFCI integration deliver more tangible value than cheaper thermostats offering superficial voice commands.

The Mysa Smart Thermostat stands out with its sleek Canadian design, HomeKit compatibility, and robust cybersecurity framework—a breath of fresh air in a market flooded with generic smart devices. Its built-in Class A GFCI and 2.4 GHz Wi-Fi optimization ensure both safety and stable connectivity, while geofencing and energy reports deliver real comfort and cost savings. For users with electric in-floor heating, Mysa solves the frustration of cold tiles and high bills by offering granular app control and temperature threshold alerts, giving peace of mind during winter freezes.

During daily use, Mysa’s intuitive app guides installation with video support, and once live, it maintains a rock-solid connection—even on mesh networks. The voice control via Siri, Alexa, and Google works flawlessly, letting users adjust heat without lifting a finger. It handles 240V systems with ease and excels in multi-room setups where remote monitoring and scheduling reduce energy waste. However, it’s strictly for electric systems only, and users with hydronic heating will find it incompatible—a hard limitation worth noting.

Compared to the OJ Microline UWG4, Mysa trades some energy analytics for superior smart home integration and user support. While the OJ offers power logging, Mysa wins with geofencing and seamless HomeKit pairing, making it ideal for Apple-centric homes. It’s the better pick for tech-savvy users who want voice control, elegant design, and strong app features without sacrificing safety. For those investing in smart flooring heat, Mysa offers a smoother, more connected experience than most high-voltage thermostats.

The meross Smart Thermostat punches far above its weight with Apple Home, Alexa, and Google integration, real-time energy monitoring, and open window detection—all at a budget-friendly price. Its ±1°F accuracy and 4-wire compatibility make it a reliable choice for baseboard and convector systems, solving the common issue of overheating and wasted energy. For renters or DIYers, the 30-minute install process and power-off memory ensure hassle-free setup and consistent performance, even during outages.

In real-world use, the thermostat’s energy monitor delivers live wattage and historical usage directly in the Meross app—ideal for users tracking carbon footprints or trimming bills. The open window detection works reliably, cutting heat when airflow is sensed, and summer mode adds versatility for cooling systems. However, it requires 4+ wires, which can exclude older installations. The LCD display is functional but not backlit, making it hard to read in dark rooms—a notable downside for nighttime use.

Next to the KING K901-W, the meross offers far more smart features and app control, though both support 240V systems. Where the KING is basic and minimalist, meross delivers home automation triggers, energy reports, and cross-platform voice control, making it the smarter long-term investment. For users seeking maximum value with deep smart home integration, meross delivers premium features at a mid-range price, outclassing pricier but less capable models.

The KING K901-W earns its place as a no-nonsense, baseboard-optimized thermostat with 3-wire compatibility, multi-voltage support (120/208/240V), and a large, easy-to-read touchscreen. Its ±1°F thermistor sensing ensures precise temperature control, while the 4 or 6-period daily programming offers flexibility for dynamic schedules—perfect for users tired of manual adjustments. For homes with electric baseboard or fan-forced heaters, this thermostat solves the problem of inefficient, unresponsive heating with reliable, programmable automation.

In practice, the K901-W delivers solid Wi-Fi performance via the Hoot app, though the interface feels dated compared to Meross or Mysa. It handles high-voltage loads without issue and maintains stable connections, but lacks energy monitoring and voice control, limiting its smart appeal. The user-defined max temperature lock is a standout for safety—ideal for homes with kids or rentals—yet the temperature cap at 90°F may feel restrictive in colder climates where higher settings are needed.

When compared to the KALOR TECH model, the KING offers better scheduling flexibility and a larger display, but at a higher cost and without proprietary wall plate convenience. It’s best for users who want dependable, programmable heat with minimal frills, prioritizing temperature precision and voltage flexibility over smart features. While it doesn’t dazzle with app gimmicks, its OTA firmware updates and 3-wire design make it a durable, future-proof choice for baseboard-only setups.

The MAXKOSKO WiFi Thermostat delivers remarkable value with its 15-foot floor sensor, Alexa and Google compatibility, and Smart Life app integration—all under $80. Its 120V/240V universal compatibility makes it a go-to for DIYers upgrading older floor heating systems, solving the common pain point of costly, complex replacements. The touchscreen LED display is bright and modern, while the programmable scheduling ensures comfort on arrival and savings when away—perfect for vacation homes or rental properties.

In real use, the MAXKOSKO connects quickly to 2.4 GHz Wi-Fi and integrates smoothly with voice assistants, though the Smart Life app can be sluggish during initial setup. It handles standard floor warming loads efficiently and the long sensor cable allows precise placement, avoiding hotspots. However, it lacks GFCI protection, a critical omission for wet areas, and offers no energy reporting or open window detection—features found even in cheaper models like meross.

Against the OJ UWG4, MAXKOSKO is half the price but half the safety, missing GFCI and adaptive learning. Yet for users with dry, low-risk installations, it offers enough smart features and solid performance to justify the savings. It’s ideal for budget-conscious buyers who want basic remote control and voice operation without investing in premium safety tech. While not the most advanced, its price-to-performance ratio makes it a strong contender for simple floor heating upgrades.

The OJ Microline UWG5 redefines smart floor control with its self-learning software, dual Wi-Fi and Bluetooth connectivity, and sleek LED touchscreen that dims automatically—minimizing light pollution at night. With built-in Class A GFCI, 120/208/240V support, and Google/Alexa integration, it combines safety, adaptability, and intelligence in one elegant package. For users seeking a hands-free, intuitive floor heating experience, the UWG5 solves the hassle of manual programming and inconsistent warmth with adaptive scheduling and voice commands.

In testing, the self-learning mode adjusts run times based on usage patterns, maintaining comfort while reducing energy waste—a feature that outperforms basic programmable models. Bluetooth pairing speeds up installation, letting contractors set it up before Wi-Fi is live. The app is intuitive and responsive, though the lack of energy metering is a surprise given OJ’s focus on efficiency. It excels in bathrooms and kitchens but, like all OJ models, offers no cooling support, limiting year-round utility.

Next to the Mysa, the UWG5 offers similar smart features but with better adaptive learning and Bluetooth setup, though Mysa edges ahead in geofencing. It’s the best pick for users who want the most intelligent, future-ready floor thermostat with industrial reliability. While pricier than most, its self-adjusting software and dual connectivity provide a smarter, more personalized experience than any other line voltage model.

The KALOR TECH Wi-Fi Thermostat wins on installation simplicity with its proprietary wall plate, pigtail wires, and all-in-one packaging—making it the easiest plug-and-play upgrade for 120–240V baseboard systems. Its Fahrenheit LCD display shows time, target temp, and Wi-Fi status at a glance, solving the confusion of blank or cluttered screens. For landlords or DIYers, the freeze protection mode is a game-changer, preventing pipe bursts during winter absences—offering real peace of mind.

In real use, the thermostat connects reliably to 2.4 GHz networks and syncs with Alexa, Google, and Smart Life/Tuya apps, allowing full remote control. The programming is straightforward, though the app lacks advanced features like energy reports. It performs well in bedrooms and guest rooms but doesn’t support 24V systems, so HVAC users will be out of luck. The lack of a backlight makes nighttime use difficult, and the display can’t show Celsius, limiting international usability.

Compared to the KING K901-W, KALOR TECH offers easier physical installation thanks to its custom wall plate and included wiring, though both lack voice smarts. It’s best for users who want a fast, foolproof upgrade with remote access and freeze protection—ideal for rentals or second homes. While not the most feature-rich, its plug-and-play design and comprehensive kit make it the most user-friendly entry in the line voltage space.