Choosing the right smart thermostat for heating and hot‑water systems can feel like a high‑stakes puzzle: a well‑tuned device not only trims your energy bills but also guarantees a cozy home the moment you step through the door, all while letting you control temperature from your phone or voice assistant.
With countless models promising sleek displays, AI‑driven scheduling, and compatibility with a growing ecosystem of smart home gadgets, it’s easy to get lost in the hype.
In this post we cut through the noise, reviewing the ten best smart thermostats that excel at managing both space heating and hot‑water supply, so you can make an informed choice with confidence.
10 Best Smart Thermostats for Heating & Hot Water Reviews
We’ve tested and compared each model to bring you the most reliable, energy‑saving options for both home heating and hot‑water control.
10. Emerson Sensi Touch Wi-Fi Smart Thermostat
The Emerson Sensi Touch Wi‑Fi Smart Thermostat blends sleek, modern aesthetics with powerful energy‑saving technology. Its 5.6‑inch full‑color touchscreen delivers crystal‑clear temperature read‑outs and intuitive menus that look great in any room.
Installation is a breeze thanks to the built‑in level, illuminated easy‑click terminals, and step‑by‑step guidance in the Sensi app—just be sure a common (C) wire is present.
Once set up, you can fine‑tune schedules, monitor usage, and receive maintenance alerts from anywhere via the iOS or Android app.
ENERGY STAR certification means you can expect roughly 23 % savings on HVAC energy, while Emerson’s privacy promise guarantees your data won’t be sold to third parties. Compatible with Alexa, the thermostat lets you adjust climate with voice commands, making comfort truly hands‑free.
| Spec | Detail |
|---|---|
| Model | ST75 |
| Dimensions | 5.625″ × 3.4″ × 1.17″ |
| Color | Black (also available in white & silver) |
| Display | 5.6‑inch color touchscreen |
| Connectivity | Wi‑Fi, Works with Alexa |
| Certification | ENERGY STAR |
| Installation | Requires C‑wire, DIY‑friendly |
| App | iOS & Android |
Best For – Homeowners who want a stylish, privacy‑focused thermostat that saves energy and integrates with Alexa.
Pros
- Easy DIY install with level, illuminated terminals, and app guidance.
- Energy savings up to ~23 % thanks to flexible scheduling and remote control.
- Smart maintenance alerts and usage reports keep HVAC performance optimal.
Cons
- Requires a C‑wire, which may need an electrician for older homes.
- Limited color options (black, white, silver) may not match every décor.
9. ecobee Smart Thermostat Essential
Save up to 23 % annually on heating and cooling with the ecobee Smart Thermostat Essential. Its intuitive color touchscreen lets you adjust the temperature with a tap, while the ecobee app tracks energy use on the go.
The thermostat learns your schedule, automatically dialing back climate control when you’re away and ramping up comfort when you return. Even without a C‑wire, the optional Power Extender Kit powers the unit, keeping installation tidy.
Seamlessly integrate with Apple HomeKit, Google Assistant, or Alexa, and add SmartSensor 2‑packs for room‑by‑room monitoring. Free software updates ensure the device stays current, and built‑in Eco+ features—humidity detection, schedule assistant, and time‑of‑use pre‑conditioning—help you shave peak‑hour costs.
| Spec | Detail |
|---|---|
| Compatibility | 85 % of HVAC systems (gas, oil, electric, dual‑fuel, heat pump, boiler) |
| Power | Works with C‑wire or optional Power Extender Kit |
| Display | 3.5‑inch color touchscreen |
| Connectivity | Wi‑Fi, Bluetooth, Apple HomeKit, Google Assistant, Amazon Alexa |
| Energy Savings | Up to 23 % yearly, Eco+ smart features |
| Sensors | Optional SmartSensor (temperature + motion) |
| Certification | ENERGY STAR Certified |
| App | ecobee iOS/Android, remote energy monitoring |
| Installation | DIY, no professional wiring required |
Best For – Homeowners who want a DIY‑friendly, voice‑controlled thermostat that maximizes comfort and cuts energy bills.
Pros
- Significant savings – up to 23 % annual reduction in heating/cooling costs.
- Broad system compatibility – works with most 24 VAC HVAC equipment.
- Smart home ready – integrates with Siri, Alexa, and Google Assistant plus optional room sensors.
Cons
- Optional accessories – Power Extender Kit and SmartSensors are sold separately.
- Limited display size – may feel small for users who prefer larger screens.
8. Amazon Smart Thermostat – ET (Model)
Amazon’s Smart Thermostat turns a regular wall‑mounted unit into a connected, energy‑saving hub. Installation is guided step‑by‑step in the Alexa app, and because it’s built on Honeywell Home’s proven technology you get reliable performance with a modern twist.
The thermostat learns your schedule, uses Echo devices or the Amazon Smart Air Quality Monitor to create comfort zones, and lets Alexa automatically switch between home, away, and sleep settings.
You can also adjust the temperature from anywhere via the Alexa app or by voice. After purchase, Amazon emails you any local utility rebates, and the ENERGY STAR certification means you’ll likely see about $50 per‑year in savings.
With Alexa+, you can bundle climate control into broader voice‑activated routines, making your home smarter without extra hardware.
| Spec | Detail |
|---|---|
| Connectivity | Wi‑Fi, works with Alexa & Ring |
| Power | Requires C‑wire (24 V) |
| Compatibility | Works with most HVAC systems |
| Certification | ENERGY STAR certified |
| Sensors | Temperature, presence detection (via Echo/Smart Air Quality Monitor) |
| Control | Alexa app, voice, on‑the‑go via smartphone |
| Warranty | 1‑year limited |
Best For – Homeowners who want an easy, Alexa‑integrated upgrade that cuts energy costs.
Pros
- Smart zoning using Echo or Air Quality Monitor for automatic comfort adjustments.
- Energy‑saving rebates and ENERGY STAR certification help lower utility bills.
- Hands‑free control via Alexa voice commands or the mobile app from anywhere.
Cons
- C‑wire required may need professional assistance for older HVAC setups.
- Limited to Alexa ecosystem, so users preferring other voice assistants won’t get full integration.
7. Amazon Smart Water Heater Timer
The Smart Water Heater Timer learns your daily routine and automatically powers your electric storage‑style water heater on and off, so you never waste energy waiting for hot water that you don’t need.
Installation takes just a few minutes—no plumbing, no tools, just snap it onto the heater’s power cord and connect to your Wi‑Fi. Through the Aquanta app you can adjust schedules, view real‑time tank temperature, and track usage trends daily, weekly, or monthly.
Integrated leak detection (with the optional sensor) sends instant alerts to prevent costly water damage. Seamlessly pair the device with Alexa or IFTTT for voice control and smart‑home automations, delivering all the convenience of a high‑end smart heater at a fraction of the price.
| Specification | Detail |
|---|---|
| Compatibility | Electric storage‑style water heaters |
| Smart Home | Alexa, IFTTT, Mobile app |
| Installation | No plumbing, plug‑and‑play (minutes) |
| Safety | UL certified, optional leak sensor |
| Energy Modes | Schedule, Boost, Eco, Vacation |
| Reporting | Tank temperature, usage analytics |
| Power | 120 V/240 V (auto‑detect) |
| Connectivity | Wi‑Fi 2.4 GHz |
Best For – Homeowners who want effortless hot‑water scheduling, energy savings, and smart‑home integration without rewiring their heater.
Pros
- Learns your routine and automates heating, cutting energy bills.
- Full remote control & voice commands via Alexa/IFTTT.
- Real‑time temperature, usage stats, and leak alerts keep you informed.
Cons
- Leak detection requires the optional sensor (extra cost).
- Only compatible with electric, not gas, water heaters.
6. Eastman 60172N Double Throw Upper Element Thermostat
The Eastman 60172N Double‑Throw Upper Element Thermostat is the reliable heart of a dual‑element water heater.
Engineered to slide into most major brands—including American, Rheem, GE, AO Smith, and Whirlpool—this black thermostat brings peace of mind with its built‑in safety switch that guards against overheating.
Its Therm‑O‑Disc SPDT design lets you toggle between two heating elements, while an adjustable temperature range of 90 °F to 150 °F lets you fine‑tune hot‑water comfort.
Installation is a breeze; the package comes with all necessary mounting hardware, and the unit is UL‑listed for added confidence. Whether you’re upgrading an aging heater or replacing a failed thermostat, the Eastman 60172N delivers dependable performance and safety in a compact, easy‑install package.
| Specification | Detail |
|---|---|
| Model | 60172N |
| Thermostat Type | Single‑Pull Double‑Throw (SPDT) Therm‑O‑Disc |
| Temperature Range | 90 °F – 150 °F |
| Compatible Heater Type | Dual‑element water heaters |
| Brands Supported | American, Craftmaster, Rheem, Richmond, GE, Kenmore, Bradford White, AO Smith, Whirlpool, Reliance |
| Safety Certification | UL‑listed |
| Voltage | 240 V |
| Amperage | 30 A (typical) |
| Mounting Color | Black |
Best For: Replacing or upgrading the upper thermostat on most dual‑element residential water heaters.
Pros
- Universal fit across a wide range of leading water‑heater brands.
- Built‑in safety switch helps prevent overheating and prolongs heater life.
- Adjustable temperature from 90 °F to 150 °F for precise hot‑water control.
Cons
- Designed only for dual‑element systems; not compatible with single‑element heaters.
- Electrical wiring may require a qualified technician for safe installation.
5. Zero KST202 Electric Thermostat
The Zero KST202 is a rugged single‑element electric thermostat designed for water‑heater tanks that operate on 120 V or 480 V single‑throw circuits.
Its compact black housing houses an adjustable temperature range that lets you fine‑tune energy consumption, while the built‑in safety switch automatically cuts power if the element overheats, protecting both the unit and your plumbing.
UL‑certified for reliable performance, the KST202 is cross‑referenced to 59T SPST + 66T, making replacement straightforward. Whether you’re upgrading an older heater or installing a new system, this thermostat delivers precise control, safety, and energy savings in a single, easy‑to‑install package.
| Specification | Detail |
|---|---|
| Model | KST202 |
| Voltage | 120 VAC / 480 VAC |
| Throw | Single |
| Element Type | Single element tanks |
| Safety | Built‑in overheat switch |
| Certification | UL |
| Cross‑reference | 59T SPST + 66T |
| Adjustability | Full temperature range |
Best For: Residential or light‑commercial water heaters that need a reliable, UL‑certified single‑element thermostat.
Pros
- Energy‑saving adjustable range reduces utility costs.
- Integrated safety switch prevents overheating damage.
- UL certification guarantees compliance and durability.
Cons
- Limited to single‑element tanks; not suitable for multi‑element systems.
- Fixed single‑throw design may require additional wiring for complex installations.
4. Honeywell Home RTH9585WF1004 Wi-Fi Smart Thermostat
The Honeywell Home RTH9585WF1004 Wi‑Fi Smart Color Thermostat blends modern design with intelligent climate control. Its vibrant, customizable color‑matched touchscreen lets you match the thermostat to any décor while delivering crystal‑clear readouts.
Connect to Wi‑Fi and manage heating or cooling from the Honeywell app, Alexa, or Google Home, so you can adjust the temperature from anywhere—even when you’re not home.
The thermostat supports 7‑day programmable schedules, flexible peak‑rate pricing, and demand‑response programs that can earn rebates or rewards from your utility.
Energy Star certification means you’ll see monthly energy reports and personalized tips to cut waste, helping you stay comfortable and save money.
Designed for forced‑air, hot‑water, steam, and heat‑pump systems (with a required C‑wire), it offers three fan modes—On, Auto, and Circulate—and integrates seamlessly with most HVAC setups. Before buying, verify C‑wire availability and compatibility with oil‑only furnaces.
| Specification | Detail |
|---|---|
| Model | RTH9585WF1004 |
| Connectivity | Wi‑Fi, Alexa, Google Home |
| Display | 3.5″ color touchscreen |
| Programming | 7‑day, flexible schedules |
| Compatibility | Forced air, hot water, steam, heat pumps (C‑wire required) |
| Fan Control | On / Auto / Circulate |
| Energy Rating | ENERGY STAR certified |
| Color Options | Customizable (matches décor) |
| Power | Requires C‑wire (adapter optional) |
| Dimensions | 5.0″ × 3.0″ × 1.2″ |
Best For – Homeowners who want a stylish, app‑controlled thermostat with utility‑rebate potential.
Pros
- Customizable color screen blends with any interior.
- Full Wi‑Fi integration for remote control via voice assistants.
- Energy‑saving features: demand‑response, ENERGY STAR reporting, and rebates.
Cons
- Requires a C‑wire; older homes may need an adapter.
- Not compatible with electric baseboard or heating‑only oil furnaces without a C‑wire.
3. Honeywell Home RTH7600D Touchscreen Thermostat
The Honeywell Home RTH7600D brings modern comfort to any home with its bright, 4‑inch backlit touchscreen that shows the current room temperature and set‑point side‑by‑side.
Its intuitive 7‑day, 4‑period‑per‑day menu lets you program a weekly schedule in seconds, while Home & Away temperatures and temporary holds give you full control over energy use when you’re away.
Smart Response Technology learns how long your furnace and air conditioner need to reach the desired temperature, so you’re never left waiting for comfort. A built‑in real‑time clock automatically adjusts for Daylight Savings Time, and an optional compressor‑delay protects your HVAC system.
Installation is straightforward, and the thermostat can alert you when it’s time to replace filters or replace low batteries. Compatible with virtually every single‑stage, multistage, heat‑pump, and even gas‑fireplace system, the RTH7600D is a versatile, user‑friendly upgrade for any climate control setup.
| Spec | Detail |
|---|---|
| Display | 4‑inch backlit touchscreen |
| Programming | 7‑day, 4 periods per day |
| Smart Response | Learns system run‑time for precise comfort |
| Real‑time Clock | Auto‑adjusts for Daylight Savings |
| Hold Options | Temporary & permanent |
| Compatibility | Single‑stage, multistage, heat‑pump, furnace, AC, gas fireplace, 750 mV, hot water, steam, gravity |
| Alerts | Filter change, low battery, compressor‑delay |
Best For: Homeowners who want a simple, programmable thermostat with smart learning and broad system compatibility.
Pros
- Large, backlit touchscreen makes programming and monitoring effortless.
- Smart Response learns HVAC run‑times, delivering comfort exactly when needed.
- Energy‑saving Home/Away and hold features reduce utility bills.
Cons
- No Wi‑Fi or app integration for remote control.
- Requires a C‑wire for full functionality on some HVAC systems.
2. EWH-00 Water Heater Thermostat
The EWH-00 Water Heater Thermostat kit gives you a complete, non‑simultaneous control solution for double‑element electric water heaters. Each kit ships with an upper and a lower thermostat, both built with a Thermo‑O‑Disc (TOD) design that snaps into action for fast, reliable temperature regulation.
The thermostats operate from 120 V up to 480 V and cover a wide temperature range of 90 °F (32 °C) to 150 °F (66 °C), making them suitable for most residential and light‑commercial units.
Engineered to meet high‑current demands, the KST series provides long‑lasting performance while complying with third‑party safety certifications. Installation is straightforward—simply replace the original units and enjoy consistent hot‑water delivery.
Backed by a one‑year warranty, the kit is an economical, hassle‑free upgrade for homeowners, plumbers, and DIY enthusiasts alike.
| Specification | Detail |
|---|---|
| Package | 1 × Upper Thermostat, 1 × Lower Thermostat |
| Voltage | 120 V – 480 V (non‑simultaneous) |
| Temp. Range | 90 °F (32 °C) – 150 °F (66 °C) |
| Style | Thermo‑O‑Disc (TOD), interchangeable with Apcom |
| Compatibility | Whirlpool, Bradford White, General Electric, Rheem, etc. |
| Warranty | 1 Year |
| Safety | Third‑party lab approved, safety marking present |
Best For: Replacing or upgrading thermostats on double‑element electric water heaters in most major brands.
Pros
- Wide voltage & temperature range fits many heater models.
- Snap‑action TOD design delivers quick, reliable on/off cycling.
- One‑year warranty and third‑party safety approval give peace of mind.
Cons
- Not suitable for simultaneous‑element heaters.
- Requires basic electrical knowledge for safe installation.
1. Sensi ST55 Smart Thermostat
The Sensi Smart Thermostat (ST55) brings a century of HVAC expertise into a sleek, button‑filled unit that feels like a traditional thermostat but works like a modern smart hub.
Installation is a breeze: the built‑in level and step‑by‑step mobile‑app guide let most DIYers finish in minutes, and most homes won’t need a dedicated C‑wire.
Once online, the Wi‑Fi‑enabled thermostat syncs with the Sensi app, Alexa, and Energy Star‑approved scheduling tools to cut heating and cooling costs by an average of 23 %.
Real‑time usage reports, filter‑change alerts, and performance insights keep your system running efficiently while the company’s strict privacy policy guarantees your data never gets sold. All this power fits neatly into the space of a standard thermostat, so you can upgrade without patching or painting.
| Spec | Detail |
|---|---|
| Model | ST55 |
| Wi‑Fi | 802.11b/g/n (2.4 GHz) |
| Voice Assistant | Works with Alexa |
| Mobile App | iOS / Android |
| Energy Star | Certified |
| Installation | DIY, no C‑wire in most cases |
| Privacy Protection | No resale of personal data* |
| Estimated Savings | ~23 % on HVAC energy* |
Best For – Homeowners who want a hassle‑free smart thermostat upgrade with strong privacy guarantees.
Pros
- Easy DIY install – built‑in level and guided app steps, no C‑wire needed for most setups.
- Energy savings – Energy Star‑certified with flexible scheduling and remote control, averaging 23 % reduction in HVAC use.
- Privacy‑first – Sensi pledges not to sell personal information to third parties.
Cons
- Limited voice ecosystem – only Alexa support; no native Google Assistant or Siri integration.
- Battery life depends on Wi‑Fi usage – heavy remote polling can shorten the 2‑year battery expectancy.
Buying Guide
Smart thermostats that manage both heating and hot water can dramatically cut energy costs, but the right model depends on build quality, feature set, durability, overall value, and real‑world feedback. Evaluating these aspects ensures you pick a device that delivers comfort, savings, and reliability over the long term.
Key Factors Buyers Should Consider
Quality
Look for a thermostat built with robust components and reliable firmware, as this ensures consistent performance over time. Certified safety standards, such as UL or CE, indicate thorough testing.
A reputable brand often provides longer warranty periods, reflecting confidence in product longevity and reducing the risk of premature failure in everyday use.
Features
Prioritize smart capabilities like Wi‑Fi connectivity, geofencing, and voice‑assistant integration, which let you adjust settings remotely. Look for programmable schedules, multi‑zone control, and compatibility with both heating and hot‑water systems.
Energy‑reporting dashboards and adaptive learning algorithms can further optimize consumption, translating convenience into measurable cost savings for homeowners seeking efficiency and ease.
Durability
Choose a model with a sturdy, weather‑resistant enclosure if it will be installed near exterior walls or in humid areas. Look for sealed buttons and a high‑resolution display that resists glare. Devices rated for a wide temperature range and backed by a solid warranty are less likely to suffer premature wear.
Value
Assess the total cost of ownership, not just the upfront price. Some thermostats require subscription services for advanced analytics or remote sensor accessories, which add recurring fees.
Compare energy‑saving potential, warranty length, and included accessories across brands to determine which option delivers the best return on investment over its lifespan.
Reviews
Read both professional test results and user feedback to gauge real‑world performance. Look for consistent praise regarding reliability, ease of installation, and app responsiveness.
Pay attention to recurring complaints, such as connectivity drops or inaccurate temperature readings, as these may indicate systemic issues that could affect long‑term satisfaction for most homeowners.
Choosing a smart thermostat that balances these factors will help you achieve reliable temperature control, lower energy bills, and lasting peace of mind.
Frequently Asked Questions
Which smart thermostats can manage both heating and hot water?
Most leading smart thermostats, such as Google Nest Learning, Ecobee SmartThermostat, Honeywell Home T9, and Tado °° Smart, integrate with boiler‑controlled hot‑water systems via OpenTherm or relay modules, letting you set separate temperature curves for domestic hot water and reduce energy waste while maintaining comfortable shower temperatures throughout the day easily.
How does a smart thermostat improve heating efficiency?
A smart thermostat learns your daily patterns, automatically lowering temperature during unoccupied periods and raising it before you return. Geofencing uses your phone’s GPS to adjust settings in real time, while remote app control lets you fine‑tune heating from anywhere, cutting unnecessary energy use and can give reports for analysis.
Can smart thermostats work with older boiler systems?
Many smart thermostats support legacy boilers through auxiliary relay modules or OpenTherm adapters, allowing basic on/off control even without full communication.
Check the manufacturer’s compatibility list; models like Honeywell Home T6R and Ecobee 4 offer retrofit kits that bridge older heating circuits to smart functionality, making them a viable upgrade.
What features should I look for when choosing a smart thermostat for heating and hot water?
Prioritize OpenTherm compatibility for precise boiler modulation, separate hot‑water scheduling, multi‑zone support, and a user‑friendly app that offers real‑time energy analytics.
Voice‑assistant integration, geofencing, and over‑the‑air firmware updates add convenience, while a clear display ensures easy on‑site adjustments. Also verify HVAC wiring compatibility and seasonal programming for year‑round comfort today.
Conclusion
Choosing the right smart thermostat hinges on balancing ease of use, integration capabilities, and energy‑saving intelligence. Look for devices that learn your schedule, offer reliable remote control, and seamlessly connect with your existing heating and hot‑water systems.
Prioritizing robust app experiences, clear display information, and compatibility with voice assistants will future‑proof your home automation setup.
By focusing on these core features, you can enjoy consistent comfort, lower utility bills, and a greener footprint without getting bogged down in technical minutiae. A well‑selected thermostat becomes the quiet command center that keeps your home cozy and efficient year after year.
