# Best smart thermostat: ENERGY STAR's own figure is 8% (about $50 a year), so the C-wire line on each maker's page decides more than the screen does > ENERGY STAR prints 8% savings, about $50 a year. ecobee Premium ships its Power Extender Kit and a sensor; Nest 4th gen prints 3 heat stages; Sensi needs a C wire. | | | |---|---| | Source | https://ownerspec.com/air/reviews/best-smart-thermostat/ | | Publisher | OwnerSpec (https://ownerspec.com/) | | Published | 2026-10-03 | | Updated | 2026-10-03 | | Facts verified | 2026-10-03 | | Disclosure | Contains affiliate links. OwnerSpec may earn a commission at no cost to the reader. | --- ## Short answer The best smart thermostat for a US home without a C wire is the ecobee Smart Thermostat Premium: ecobee's page prints a Power Extender Kit and a SmartSensor in the box, 24 VAC wiring through C and Rc, up to 2-stage heating and cooling and a 3-year warranty, and ENERGY STAR's certified list carries its EB-STATE6 row. The Google Nest Learning Thermostat (4th gen) is the pick for 3-stage heat, a multi-stage heat pump or Matter: Google's spec page prints W1-W3 and Y1-Y3 terminals and 20-30 VAC input. If the wall already has a C wire, the Amazon Smart Thermostat is the cheapest ENERGY STAR-listed unit here. Keep expectations at the program's own figure: ENERGY STAR's technical bulletin says the average home saves 8% on heating and cooling costs, about $50 a year. Skip every unit on this page if the heat is electric baseboard: Google and ecobee both say 120 V and 240 V systems are not compatible. ## Fact sheet - **Answer:** ENERGY STAR's technical bulletin says a certified smart thermostat saves the average home 8% on heating and cooling costs, about a year. For a home without a C wire the ecobee Smart Thermostat Premium ships its Power Extender Kit and a SmartSensor in the box on 24 VAC; the Google Nest Learning Thermostat (4th gen) prints W1-W3 and Y1-Y3 terminals and Matter; the Sensi Touch 2 and Amazon Smart Thermostat require a C wire. - **Comparison basis:** Manufacturer product and support pages for ecobee (Premium, Enhanced, Essential, Power Extender Kit, HVAC compatibility), Google Nest (compatibility, C-wire, technical specifications), Copeland's Sensi Touch 2 spec sheet R-5530, Honeywell Home's T9 page and Honeywell Store's C-wire guide, Mysa's line-voltage product page, and ENERGY STAR's technical bulletin, key product criteria and certified smart thermostat dataset, compared on certification row and date, C-wire requirement and the maker's substitute, stages and heat pump support, remote sensor, display, voice assistant, Matter and warranty. - **Assumptions:** A low-voltage 24 VAC US furnace, air conditioner or heat pump; every maker here says electric baseboard and other 120/240 V systems are not compatible; The ENERGY STAR dataset was queried through data.energystar.gov on 2026-10-03 (120 rows); a model with no row that day is reported as not found, not as uncertified; Savings figures are ENERGY STAR's program average; maker savings claims are marketing numbers and are left off this page - **Method:** OwnerSpec compared manufacturer-published specifications and ENERGY STAR's published list on 2026-10-03 and confirmed each linked listing in stock the same day; it did not install, run or measure any thermostat, and prints only the figures the cited document states. - **Primary source:** [ENERGY STAR, Technical Bulletin: ENERGY STAR Certified Smart Thermostats (PDF)](https://www.energystar.gov/sites/default/files/asset/document/Technical_Bulletin_ENERGY_STAR_Smart_Thermostats_508.pdf) (government or regulatory source) - **Facts verified:** 2026-10-03 - **Last updated:** 2026-10-03 - **Canonical URL (cite this):** https://ownerspec.com/air/reviews/best-smart-thermostat/ If your heater is a 120 V or 240 V baseboard, this is the wrong page: every thermostat below is a 24 V device, and the last section names the kind you need instead. ## How was this shortlist built? OwnerSpec compared manufacturer-published specifications and ENERGY STAR's published list on 2026-10-03 and confirmed every linked listing in stock the same day. Nothing on this page was installed, run or measured. The fields compared are the ones a maker or ENERGY STAR prints: the certified list row and its date, the C-wire requirement and the maker's substitute, stages and heat pump support, remote sensor, display, voice assistant, Matter and warranty. "Certified" here means the model appears in ENERGY STAR's own dataset, not that the maker says so. Three candidates were dropped: Honeywell's page marks the T9 kit "Discontinued and sold out," the Google Nest Thermostat was not confirmed in stock on the day, and the Honeywell T5 was not buyable. ## What does ENERGY STAR certified actually promise? ENERGY STAR's technical bulletin says certified smart thermostats "have been independently certified to deliver energy savings based on actual field data. In fact, the average home saves 8% on heating and cooling costs, or $50 per year." That is the number to hold every maker claim against. The key product criteria page prints the floor a model has to clear: | Criterion | ENERGY STAR requirement | | --- | --- | | Temperature accuracy | within 2.0 F | | Network standby power | 3.0 W average or less | | Time to enter standby | 5.0 minutes or less | | Heating runtime reduction | at least 8% at 95% confidence, or 4% at the 20th percentile | | Cooling runtime reduction | at least 10% at 95% confidence, or 5% at the 20th percentile | | Without connectivity | must still work as a basic thermostat | | Features | a schedule, HVAC run-time information, utility demand-response ability | The bulletin adds that "many do recommend a C wire for new installations," and that "with variable-speed equipment, the thermostat recommended by the equipment manufacturer should be used." The [setback savings calculator](/air/calculators/thermostat-setback-savings-calculator/) turns the 8% into dollars at your own bill. ## Which thermostats need a C wire, and what does each maker ship instead? Honeywell Store's guide defines the term: "A C-wire, also called a common wire, provides a continuous 24V power path from the HVAC system to the thermostat." R supplies the 24 V, C completes the path. The [C-wire guide](/air/guides/smart-thermostat-c-wire-compatibility/) walks through the wall plate. | Model | C wire | What the maker ships or sells instead | Source | | --- | --- | --- | --- | | ecobee Smart Thermostat Premium | Powered on 24 VAC through C and Rc | Power Extender Kit in the box | ecobee product page | | ecobee Smart Thermostat Enhanced | Same | Power Extender Kit in the box | ecobee product page | | ecobee Smart Thermostat Essential | "Requires a common wire" | Power Extender Kit sold separately | ecobee product page | | Nest Learning Thermostat (4th gen) | Google Home app tells you during setup | Nest Power Connector if no spare wire | Google C-wire help page | | Nest Thermostat | Needed on heat-only, cool-only, single-stage heat pump and dual fuel | Nest Power Connector | Google compatibility page | | Sensi Touch 2 | "All systems require a common wire (c-wire)" | Common wire kit SA11, an accessory | Copeland spec sheet R-5530 | | Honeywell Home T9 | Adapter bundled | C-Wire Adapter in the kit | Honeywell Home T9 page | | Amazon Smart Thermostat | Listing title: "C-wire required" | Not confirmed; help page unreadable | Amazon listing title only | | Honeywell Home RTH9600WF | Listing title: "C-Wire Required" | Not confirmed | Amazon listing title only | ecobee's Power Extender Kit page sets the kit's limit: it "only works with 24 VAC systems. Millivolt, high-voltage systems, dual transformer and fan coil or communicating units are incompatible." ## How do the units compare on paper? | Model | ENERGY STAR list row (qualified) | Stages and heat pump (maker) | Remote sensor | Display | Voice and Matter | Warranty | | --- | --- | --- | --- | --- | --- | --- | | ecobee Premium | EB-STATE6* (2023-04-25) | Up to 2-stage heating and cooling, heat pumps | SmartSensor in box | 4 in, 540 x 540 touch | Alexa built-in, Siri via HomePod; Matter not printed | 3 years | | Nest Learning (4th gen) | GA05###-** (2024-04-24) | W1-W3, Y1-Y3; heat pump up to 4 heating stages | Nest Temperature Sensor (2nd gen) | 2.68 in, 600 x 600 | Google Home, Matter | Not printed on the spec page | | ecobee Enhanced | EB-STATE6L* (2025-12-16) | 2H/2C, heat pumps 2H/2C plus 1 AUX | Compatible, sold separately | Not printed | HomeKit, Alexa, SmartThings; Matter not printed | 3 years, 5 with pro install | | ecobee Essential | No row found 2026-10-03 | 2C+1H or 2H+1C, dual-fuel heat pumps | Sold separately | Not printed | Not printed on the page read | 3 years | | Sensi Touch 2 | ST76 (2022-06-28) | Single and multi-stage, heat pumps, dual fuel without outdoor sensor | RS01-SG | Touchscreen, size not printed | Alexa, Google Assistant, SmartThings; Matter not printed | 3-year limited | | Amazon Smart Thermostat | S6ED3R (2023-06-21) | Not confirmed | Not confirmed | Not confirmed | Listing title: Alexa and Ring | Not confirmed | | Honeywell RTH9600WF | RTH9600WF2022 (2019-08-01) | Not confirmed | Not confirmed | Colour touchscreen per title | Listing title: Alexa Ready | Not confirmed | | Nest Thermostat (not confirmed in stock) | GA0####-** (2020-11-01) | Needs C wire or Power Connector on heat pump and dual fuel | Not supported | 2.4 in, 240 x 320 | Google Home; Matter not listed | Not printed | "Not printed" means the document read does not list it. "Not confirmed" means no maker document for that model was readable. ## ecobee Smart Thermostat Premium: buy it or skip it? Buy it if the wall has no C wire and you want a room sensor from day one. ecobee's page prints 24 VAC through terminals C and Rc, the Power Extender Kit and a SmartSensor in the box, furnaces, air conditioners and heat pumps up to 2-stage, a 4 in 540 x 540 touchscreen, Alexa built in, Siri through an Apple HomePod, dual-band Wi-Fi and a 3-year limited warranty. ENERGY STAR's list carries the EB-STATE6 row from 2023-04-25. The flaw is the stage count: two stages of heat is the ceiling ecobee prints, so a 3-stage system is the Nest's territory. Matter is not on the page read. Skip it if the furnace is variable-speed: ENERGY STAR's bulletin defers to the equipment maker. ## Google Nest Learning Thermostat (4th gen): buy it or skip it? Buy it if the system has more stages than a two-stage thermostat can drive, or for Matter. Google's technical specifications page prints 20-30 VAC input, W1-W3 heating and Y1-Y3 cooling terminals, a 2.68 in 600 x 600 display, Wi-Fi on 2.4 and 5 GHz, Google Home and Matter, the Nest Temperature Sensor (2nd gen) and a rechargeable lithium battery. Google's compatibility page adds up to 2 cooling and 3 heating stages, and up to 4 heating stages on a heat pump including 2 heat pump stages; the linked bundle includes one sensor. The flaw is the C-wire answer, which is "it depends." Google's help page says only that the Google Home app "will often tell you during setup if you need to connect a C wire," with the Nest Power Connector as the fallback. No warranty figure appears on the spec page read. Skip it if you want Alexa or Siri inside the thermostat: Google's page lists Google Home and Matter, nothing else. ## ecobee Enhanced and Essential: buy them or skip them? Buy the Enhanced for the Premium's wiring answer without the sensor in the box. ecobee prints the Power Extender Kit included, 2H/2C conventional systems and heat pumps with 1 stage of AUX heat, SmartSensor compatibility, Apple HomeKit, Alexa and SmartThings, and a 3-year warranty that becomes 5 with professional installation. Its ENERGY STAR row, EB-STATE6L, is dated 2025-12-16. Buy the Essential only if a C wire is already there, or you will add the kit. ecobee's page says it "requires a common wire," sells the Power Extender Kit separately, and prints 2 cooling plus 1 heating stage or 2 heating plus 1 cooling, dual-fuel heat pumps, radiant heat and a 3-year warranty. The flaw with the Essential is a paperwork gap: ecobee says ENERGY STAR certified, yet the ENERGY STAR dataset queried on 2026-10-03 returned no Essential row among its 120 rows. Until it does, this page credits the claim to ecobee, not to ENERGY STAR. ## Sensi Touch 2: buy it or skip it? Buy it if the wall has a C wire and the system is a dual-fuel heat pump. Copeland's spec sheet R-5530 prints 20 to 30 VAC, 1.5 A per terminal and 2.5 A total, single and multi-stage gas, oil, electric and heat pump systems, "automatic dual fuel control without an outdoor sensor," a 45 to 99 F setpoint range, the RS01-SG room sensor, Wi-Fi on 2.4 or 5 GHz, Alexa, Google Assistant and SmartThings, and ENERGY STAR CERTIFIED. The list row is ST76, dated 2022-06-28. The flaw is the first line on the sheet: "All systems require a common wire (c-wire)." The sheet names a common wire kit, SA11, as an accessory, not as box contents. The sheet prints a 3-year limited warranty; Matter is not printed. Skip it if you have four wires and no C: the ecobee kits above answer that wall. ## Amazon Smart Thermostat and Honeywell Home RTH9600WF: buy them or skip them? Buy the Amazon Smart Thermostat if a C wire is present and the ENERGY STAR row is all you need. The certified list carries model S6ED3R from 2023-06-21, and the listing title prints "C-wire required" and "Works with Alexa and Ring." The flaw is that this page can say nothing else about it: Amazon's compatibility help page returned an error every time, so heat pump, dual-fuel and adapter details are unconfirmed. The Honeywell Home RTH9600WF sits in the same position: an ENERGY STAR row (RTH9600WF2022, 2019-08-01) and a listing title printing "C-Wire Required" and "Alexa Ready," with no Resideo spec page opened this session. Skip both if there is no C wire at the wall; neither listing names an adapter in the box. **Pull the wall plate before you order** Do not buy any thermostat here until you have counted the wires behind the old one and read the labels, not the colours: ecobee's support page says wire colours are not standardised. A wire on C opens up the Sensi, the Amazon and the Honeywell; four wires and no C sends you to an ecobee with the kit in the box. The [C-wire guide](/air/guides/smart-thermostat-c-wire-compatibility/) shows what each label means, and the [deal check](/air/guides/smart-thermostat-black-friday-prime-day-deal-check/) says when the prices on the cards above tend to move. ## Who should skip every thermostat here? **Electric baseboard, wall or ceiling heat on 120 V or 240 V.** Google's compatibility page says "high voltage systems, such as electric baseboard heaters, aren't compatible with Nest thermostats." ecobee's support page says a high-voltage thermostat is labelled 120 V or 240 V, or has L1/L2 labels and thick wire nuts, and is not compatible unless a professional fits a step-down transformer. Mysa's line-voltage baseboard thermostat is rated for 120-240 VAC at a 16 A maximum load, 3,800 W at 240 V and 1,900 W at 120 V; Mysa says regular low-voltage smart thermostats are not compatible. **Millivolt heaters.** Google and ecobee both list millivolt wall and floor heaters as incompatible. **Proprietary, communicating and variable-speed systems.** ecobee lists non-standard wire labels (1, 2, 3, 4 or A, B, C, D) and communicating units as incompatible; ENERGY STAR's bulletin covers variable-speed equipment, above. ## What goes wrong? **The thermostat reboots or the battery drains.** Google's C-wire page says a Nest Thermostat E or a 3rd-gen Learning Thermostat with power issues or a draining battery needs a C wire. **Power was never switched off.** ecobee's support page says to cut power at the HVAC switch or the breaker first, then confirm by changing the setpoint at least five degrees. **The filter is the real problem.** A furnace that cannot hold temperature is not a thermostat fault; the [furnace filter interval](/air/guides/how-often-change-furnace-filter/) is the first and cheaper check. **The savings never show up.** ENERGY STAR's bulletin says owners "will need to connect their smart thermostats to WiFi to realize the full benefits," and 8% is an average, not a promise. ## The picks - **ecobee Smart Thermostat Premium**: No C wire, wants a room sensor and voice built in (ecobee product page: 24 VAC through C and Rc, Power Extender Kit and SmartSensor in the box, conventional and heat pump systems up to 2-stage heating and cooling, 4 in 540 x 540 touchscreen, Alexa built-in, Siri via HomePod, dual-band Wi-Fi, 3-year limited warranty; ENERGY STAR list row EB-STATE6*, qualified 2023-04-25) Amazon: https://www.amazon.com/dp/B09XXS48P8/?tag=ownerspec-20 - **Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen)**: Has 3-stage heat, a multi-stage heat pump or wants Matter (Google spec page: 20-30 VAC input, W1-W3 heating and Y1-Y3 cooling terminals, 2.68 in 600 x 600 display, Wi-Fi 2.4 and 5 GHz, Google Home and Matter, Nest Temperature Sensor (2nd gen) supported, rechargeable lithium battery; ENERGY STAR list row GA05###-**, qualified 2024-04-24) Amazon: https://www.amazon.com/dp/B0D5BBYRJM/?tag=ownerspec-20 - **ecobee Smart Thermostat Enhanced**: No C wire, does not need a sensor in the box (ecobee product page: Power Extender Kit included, most 24 VAC equipment including 2H/2C conventional and heat pumps with 1 stage AUX heat, SmartSensor compatible (sold separately), Apple HomeKit, Alexa, SmartThings, 3-year warranty (5 with professional install); ENERGY STAR list row EB-STATE6L*, qualified 2025-12-16) Amazon: https://www.amazon.com/dp/B09XXTQPXC/?tag=ownerspec-20 - **ecobee Smart Thermostat Essential**: Cheapest ecobee, has a C wire or will buy the kit separately (ecobee product page: requires a common wire, Power Extender Kit sold separately, radiant heat and dual-fuel heat pumps, 2 cooling plus 1 heating stage or 2 heating plus 1 cooling, SmartSensors sold separately, 3-year warranty; ecobee prints ENERGY STAR certified, but the ENERGY STAR certified list queried on 2026-10-03 returned no Essential row) Amazon: https://www.amazon.com/dp/B0DT9MC2Z9/?tag=ownerspec-20 - **Sensi Touch 2 (ST76)**: Has a C wire and a dual-fuel heat pump (Copeland spec sheet R-5530: common wire required on all systems, 20-30 VAC, 1.5 A per terminal and 2.5 A total, single and multi-stage gas, oil, electric and heat pump, dual fuel without an outdoor sensor, 45-99 F setpoint range, Sensi room sensor RS01-SG, Wi-Fi 2.4 or 5 GHz, Alexa, Google Assistant and SmartThings, ENERGY STAR CERTIFIED; list row ST76, qualified 2022-06-28) Amazon: https://www.amazon.com/dp/B0BKH83KF9/?tag=ownerspec-20 - **Amazon Smart Thermostat (C-wire required)**: Has a C wire and wants the cheapest ENERGY STAR-listed unit here (ENERGY STAR certified list row S6ED3R, qualified 2023-06-21; the listing title prints C-wire required and works with Alexa and Ring; Amazon's compatibility help page would not load this session, so heat pump and dual-fuel support are not confirmed from a maker document) Amazon: https://www.amazon.com/dp/B08J4C8871/?tag=ownerspec-20 - **Honeywell Home RTH9600WF Smart Color Thermostat (C-wire required)**: Has a C wire and wants a large colour touchscreen (ENERGY STAR certified list row RTH9600WF2022 under RTH9585WF / RTH9600WF****, qualified 2019-08-01; the listing title prints C-Wire Required and Alexa Ready; no Resideo spec page for this model was opened this session) Amazon: https://www.amazon.com/dp/B09TBGGLQB/?tag=ownerspec-20 ## Frequently asked questions ### How much does an ENERGY STAR smart thermostat actually save? ENERGY STAR's technical bulletin on certified smart thermostats says the average home saves 8% on heating and cooling costs, or $50 per year, and that the certification rests on field data rather than a lab test. The key product criteria page sets the floor: a heating runtime reduction of at least 8% and a cooling runtime reduction of at least 10% at 95% confidence. Maker claims above that are marketing. ### Which smart thermostats work without a C wire? ecobee bundles its Power Extender Kit with the Smart Thermostat Premium and Enhanced and sells it separately for the Essential; the kit works only on 24 VAC systems. Google says the Nest Thermostat and Nest Learning Thermostat (4th gen) tell you during setup whether a C wire is needed, with the Nest Power Connector as the substitute. Copeland's Sensi Touch 2 spec sheet says all systems require a common wire. ### Can a smart thermostat run electric baseboard heaters? Not the ones on this page. Google's compatibility page says high-voltage systems such as electric baseboard heaters are not compatible with Nest thermostats, and ecobee's support page says the same for 120 V and 240 V systems, which carry L1/L2 labels and thick wire nuts. Mysa's baseboard thermostat is built for 120-240 VAC heating and prints a 16 A maximum load, 3,800 W at 240 V. ### Do smart thermostats work with heat pumps and dual fuel? The makers print the limits. Google's spec page gives the Nest Learning Thermostat (4th gen) W1-W3 heating and Y1-Y3 cooling terminals and up to 4 heating stages on a heat pump. ecobee's Enhanced page prints 2H/2C heat pumps plus 1 stage of auxiliary heat, and the Essential page names dual-fuel heat pumps. Copeland's Sensi Touch 2 sheet prints multi-stage heat pumps and automatic dual fuel control without an outdoor sensor. ### Is the ecobee Smart Thermostat Essential ENERGY STAR certified? ecobee's product page says the Essential is ENERGY STAR certified, and the Amazon listing title repeats it. The ENERGY STAR certified smart thermostat dataset queried on 2026-10-03 returned 120 rows, including ecobee's Premium, Enhanced, ecobee 7 and ecobee3 lite, but no row for the Essential by name or model prefix. OwnerSpec reports that gap rather than attributing the certification to ENERGY STAR for this model. ## Sources - [ENERGY STAR, Technical Bulletin: ENERGY STAR Certified Smart Thermostats (PDF)](https://www.energystar.gov/sites/default/files/asset/document/Technical_Bulletin_ENERGY_STAR_Smart_Thermostats_508.pdf) (government or regulatory source) - [ENERGY STAR, Smart Thermostats Key Product Criteria](https://www.energystar.gov/products/smart_thermostats/key_product_criteria) (government or regulatory source) - [ENERGY STAR, Certified Smart Thermostats dataset (data.energystar.gov)](https://data.energystar.gov/Active-Specs/ENERGY-STAR-Certified-Smart-Thermostats/7p2p-wkbf) (government or regulatory source) - [ENERGY STAR, Smart Thermostats product page](https://www.energystar.gov/products/smart_thermostats) (government or regulatory source) - [ecobee, Power Extender Kit](https://www.ecobee.com/en-us/thermostat-accessories/power-extender-kit/) (manufacturer or vendor document) - [ecobee, Smart Thermostat Premium product page](https://www.ecobee.com/en-us/smart-thermostats/smart-thermostat-premium/) (manufacturer or vendor document) - [ecobee, Smart Thermostat Enhanced product page](https://www.ecobee.com/en-us/smart-thermostats/smart-thermostat-enhanced/) (manufacturer or vendor document) - [ecobee, Smart Thermostat Essential product page](https://www.ecobee.com/en-us/smart-thermostats/smart-thermostat-essential/) (manufacturer or vendor document) - [ecobee support, What types of HVAC systems are ecobee thermostats compatible with?](https://support.ecobee.com/s/articles/What-types-of-HVAC-systems-are-ecobee-thermostats-compatible-with) (manufacturer or vendor document) - [Google Nest Help, Nest thermostat compatibility](https://support.google.com/googlehome/answer/9246656?hl=en) (manufacturer or vendor document) - [Google Nest Help, Learn about the common or C wire](https://support.google.com/googlehome/answer/9251212?hl=en) (manufacturer or vendor document) - [Google Nest Help, Nest thermostat technical specifications](https://support.google.com/googlehome/answer/9230098?hl=en) (manufacturer or vendor document) - [Copeland, Sensi Touch 2 spec sheet R-5530 (PDF)](https://media.copeland.com/70cc5282-dca0-426b-83db-b16b010c8b50/R-5530%20-%20Touch%202%20-%20Retail%20-%20Spec%20Sheet.pdf) (manufacturer or vendor document) - [Honeywell Home, T9 Smart Thermostat with sensor and C-wire adapter](https://www.honeywellhome.com/us/en/products/air/thermostats/wifi-thermostats/t9-smart-thermostat-and-sensor-with-c-wire-adaptor-smhom9610kit/) (manufacturer or vendor document) - [Honeywell Store, Thermostat C-Wire and Adapter Guide](https://www.honeywellstore.com/store/product-support/thermostat-c-wire-adapter-guide.htm) (manufacturer or vendor document) - [Mysa, Smart Thermostat for Electric Baseboard Heaters](https://getmysa.com/en-us/products/mysa-baseboard) (manufacturer or vendor document) --- Citation: OwnerSpec, "Best smart thermostat: ENERGY STAR's own figure is 8% (about $50 a year), so the C-wire line on each maker's page decides more than the screen does", https://ownerspec.com/air/reviews/best-smart-thermostat/, facts verified 3 October 2026. 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