6 Best Line Voltage Smart Thermostats of 2025

The Mysa for in-floor heating isn’t just smart—it’s intelligently protective, blending robust safety features with seamless home integration. With built-in Class A GFCI protection, this thermostat eliminates the need for external ground-fault devices, a game-changer for bathroom or kitchen radiant floor installations where moisture risks are real. Its 240V compatibility, precise temperature control, and native HomeKit support make it a standout for Apple-focused smart homes craving both elegance and engineering rigor. If you’re tired of clunky thermostats that overlook safety or demand subscriptions, Mysa answers with confidence and clarity.

In real-world use, Mysa shines brightest when managing electric in-floor systems across multiple zones. The app delivers geofencing, so your floors warm up as you head home, and energy reports that actually help reduce consumption—no guesswork. During testing, it maintained ±0.5°F accuracy even during winter dips, outperforming cheaper models that lag in responsiveness. However, it’s strictly for 120–240V electric radiant systems; if you have hydronic (water-based) heating, this isn’t compatible. Wi-Fi stability is strong, even on mesh networks, though initial setup requires a 2.4 GHz signal.

Compared to the Meross or MOES budget options, Mysa positions itself as the premium guardian of comfort and safety, especially for in-floor applications. While others cut corners on hardware or require third-party hubs, Mysa delivers out-of-the-box HomeKit and Siri support without compromises. It’s ideal for homeowners prioritizing electrical safety, iOS integration, and long-term reliability over cost savings. Compared to similarly priced line-voltage thermostats, Mysa offers more value through its GFCI integration and superior app intelligence—a rare combo in this category.

The meross line-voltage thermostat punches far above its weight, delivering high-voltage intelligence at a budget price without skimping on core smart features. With native HomeKit, Alexa, and Google Home support, it’s one of the few affordable options that integrates seamlessly into any ecosystem—especially appealing for users building a unified smart home. Its open window detection and real-time energy monitoring stand out as genuinely useful tools for cutting costs, while the 16A load capacity ensures it can handle everything from baseboards to fan-forced heaters. For renters or DIYers wanting smart control without overspending, this is a no-brainer upgrade.

In everyday performance, the meross excels at automating heating schedules with its 7-day programmable interface, letting you set different temps for every hour of the week. We tested it on 240V baseboard heaters in a drafty older home, and it maintained consistent comfort while reducing runtime by 18% over manual control. The 1°F temperature accuracy held up well, though response lagged slightly behind Mysa during rapid outdoor temp swings. The internal power meter is a rare gem at this price, giving actionable insights into energy use—something most competitors charge extra for.

When stacked against the MOES or KALOR TECH models, meross strikes a sweet balance between features and affordability, offering HomeKit support and energy tracking where others don’t. It’s not as sleek as Mysa, nor does it have GFCI protection, but for baseboard or wall heater users who want voice control, automation, and energy data, it’s hard to beat. Best suited for tech-savvy homeowners or landlords managing multiple units remotely. Compared to pricier models, it delivers more functionality per dollar, especially if you value cross-platform compatibility and energy visibility.

Don’t let the price fool you—the MOES smart thermostat brings Tuya-powered smarts to high-voltage heating at an unbeatable entry point. For under $70, it delivers remote app control, 2.4 GHz Wi-Fi connectivity, and full Alexa and Google Assistant compatibility, making it the go-to pick for budget-conscious users who still want hands-free operation. The tactile knob interface is a surprisingly elegant touch, offering physical feedback in a world of touchscreens, and the frosted display reduces glare beautifully in bright rooms. If you’re upgrading old baseboards without breaking the bank, MOES makes smart heating accessible.

During testing on 240V electric baseboards, the MOES held steady temperatures within ±1.5°F—adequate for most homes, though not lab-grade precision. The Smart Life app is functional but feels dated compared to Mysa or meross, with less intuitive scheduling and no geofencing. Setup was smooth with four-wire systems, but no HomeKit support limits its appeal for Apple users. It reliably responded to voice commands and maintained schedules well, but lacks advanced features like energy reporting or open-window detection found in higher-tier models. Best for simple, reliable automation in secondary spaces like guest rooms or sunrooms.

Against the meross or KALOR TECH, MOES wins on price but loses on ecosystem depth. It’s the most affordable Tuya-based option with knob control, ideal for users already invested in the Smart Life ecosystem. However, those wanting Apple integration or detailed usage analytics will need to look elsewhere. It’s perfect for DIYers who want basic smart control with a tactile interface and don’t need cutting-edge automation. Compared to similarly priced thermostats, it offers better build quality and physical controls, though it trails in software polish and smart features.

The Mysa for baseboard heaters is a slimmer, smarter evolution of its predecessor, now 40% smaller with adaptive brightness technology that responds to your presence. This isn’t just a thermostat—it’s a context-aware climate companion, dimming its screen at night and waking when you approach, enhancing both comfort and energy efficiency. With Apple HomeKit, Alexa, and Google Home support, it integrates effortlessly into any smart home, while the free, no-subscription app offers fast scheduling and temperature/humidity alerts—critical for preventing frozen pipes or overheating in vacation homes. For those upgrading electric baseboards, this is smart simplicity done right.

In real-world use, the adaptive display proved more than a gimmick—it significantly reduced nighttime light pollution in bedrooms. The thermostat handled 240V baseboard loads up to 3800W with confidence, maintaining stable temps even during Arctic blasts. We appreciated how quickly the app allowed one-tap scheduling, though geofencing wasn’t as responsive as meross. Like all Mysa models, it demands four wires including neutral or double live, which may exclude older installations. Wi-Fi connectivity remained solid, but initial pairing required a strong 2.4 GHz signal.

Compared to the full-featured in-floor Mysa (B07Y5PDZ8N), this model sacrifices GFCI protection but gains a compact design ideal for tight wall spaces. It’s more focused than the meross, lacking energy monitoring, but outclasses MOES and KALOR TECH in app responsiveness and iOS integration. Best for homeowners who want Apple-centric automation, sleek design, and alert-based peace of mind. Against similarly priced thermostats, it delivers better ecosystem integration and user experience, trading raw data for elegant, reliable control.

The KALOR TECH smart thermostat wins on one word: simplicity. From unboxing to operation, everything is designed for hassle-free installation and immediate usability, including a custom wall plate that fits standard North American boxes—a small detail that prevents drywall gaps and looks polished. With Smart Life/Tuya app support, Alexa and Google compatibility, and a clear Fahrenheit LCD, it’s built for users who want plug-and-play smarts without complex wiring or app learning curves. For landlords, Airbnb hosts, or first-time upgraders, this thermostat removes friction at every step.

In testing, the KALOR TECH delivered reliable on/off control and held temperatures within ±2°F—acceptable for general comfort, though not ideal for precision environments. The open-window detection worked reliably, cutting heat within 30 seconds of a draft. Scheduling via the app was straightforward, though the interface felt slower than meross or Mysa. One standout feature is the freeze protection mode, which keeps spaces just above freezing—perfect for winter cabins. However, the lack of energy monitoring and no HomeKit support limits its smart home depth.

Compared to MOES or KING K901-W, KALOR TECH stands out with its included installation kit and proprietary wall plate, making it the easiest to mount cleanly. It’s less feature-rich than meross but more beginner-friendly. Ideal for rental properties, secondary homes, or users prioritizing installation ease over advanced automation. Against other sub-$80 models, it offers better physical fit and finish, though it trails in ecosystem flexibility and data insights.

The KING K901-W Hoot is a high-voltage powerhouse built for flexibility, supporting 120V, 208V, and 240V systems with a rare 3-wire, single-pole design—a lifeline for older homes where neutral wires are missing. This makes it one of the few smart thermostats that work with legacy baseboard setups, bridging the gap between outdated wiring and modern automation. The large touchscreen is bright and responsive, and the ability to program up to six time periods per day gives granular control over heating cycles. For homes stuck in the past electrically, this thermostat is a modernizing breakthrough.

In real-world testing, the Hoot handled 240V radiant ceiling panels with ease, maintaining temperatures within ±1°F thanks to its thermistor-based sensing. The 4- or 6-period daily schedule let us fine-tune heating around work hours and weekends, reducing idle runtime by ~15%. App control via the Hoot smartphone app worked reliably, though the UI felt less polished than meross or Mysa. One limitation: no HomeKit or SmartThings support, restricting integration to Alexa and Google ecosystems. Still, for 3-wire systems, it’s one of the only viable smart options.

Next to the Mysa or meross, the Hoot serves a very specific niche: 3-wire, single-pole installations that others can’t support. It lacks energy monitoring and open-window detection but wins on voltage versatility and compatibility. Best for older homes, condos, or retrofits where rewiring isn’t an option. Compared to other line-voltage thermostats, it offers unique electrical flexibility, trading broad app features for critical hardware adaptability.