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Smart thermostat guides: 18 models, one plain row each
Each row says who the model suits, its main strength and its main catch, taken from each guide's listed sources. Open a guide to confirm the exact model and what's included before you buy on Amazon.
| Product | Best for | Main strength | Main caveat |
|---|---|---|---|
| Sensi Smart Thermostat ST55 | Conventional or heat pump systems within Copeland's 2H/2C and 4H/2C stage list, on a 2.4GHz network | Copeland's shop page prints the listing's model number and UPC, and its 2024 guides name the ST55 | C wire required for heat-only, cool-only, heat pumps and three-wire zones; HomeKit needs one and a compatible unit |
| Google Nest Thermostat (Charcoal) | 24V systems within Google's stage list: one stage each, plus one extra stage | Google says it is designed to work without a C wire, with named exceptions, on 2.4 or 5 GHz Wi-Fi | One extra stage only: Google lists no two-stage heat with two-stage cooling |
| Mysa Smart Thermostat V2 for Electric Baseboard Heaters (BB.2.0.01.NA-US) | 120V or 240V electric baseboard, fan-forced convector and radiant ceiling heat in a standard gang box | Built for 120V and 240V electric baseboard, fan-forced and radiant ceiling heat, per the maker's sheet | Not compatible with 24 V, millivolt, central hydronic or electric in-floor systems |
| Sensi Touch 2 Smart Thermostat ST76 (Black) | Homes with a C wire and up to 2H/2C or 4H/2C heat pump equipment | Copeland lists up to 2H/2C conventional and 4H/2C heat pump staging, plus humidity control | A C wire is required on every system |
| Sensi Lite Smart Thermostat ST25 (Black) | Single-stage or one-extra-stage 24 VAC systems on a 2.4 GHz network | Listing and maker agree on exactly which systems need a C wire | Only one extra stage: no 2H/2C, and no two-stage heat pump support |
| Honeywell Home RTH6580WF Wi-Fi 7-Day Programmable Thermostat (White) | 24 VAC forced-air, hydronic or heat pump systems that already have a C wire | Maker lists up to 2H/2C conventional and 3H/2C heat pump staging | C wire is mandatory: without it the thermostat will not power up |
| Honeywell Home T9 Smart Thermostat with 1 Room Sensor RCHT9610WFSW2003 | 24 VAC systems up to 3 heat/2 cool where room-by-room sensing appeals | C-wire adapter is in the box, per the maker page and guide | Adapter fitting is more complicated on zoned systems, per the guide |
| Honeywell Home T5 Smart Thermostat RTH8800WF2022 | 24 VAC systems with a C wire, up to 2 heat/2 cool, on a 2.4 GHz network | Temperature stays adjustable at the unit if Wi-Fi drops | C wire required and no adapter listed in the box |
| Honeywell Home X2S Smart Wi-Fi Thermostat RTH2SMC/N (White) | 24 VAC conventional systems up to 2H/2C, or single-stage heat pumps with electric backup | Guide spells out exactly which heat pump set-ups it supports | Heat pumps: one compressor stage and electric backup only, no gas or oil |
| Honeywell Home X2P Programmable Thermostat RTH20B (White) | Single-stage 1 heat/1 cool systems where Wi-Fi is not needed | Battery powered; the guide says a C wire does not power it | Schedule conflict: guide says 5-2 only; maker spec table lists 7-day too |
| Honeywell Home X8S Smart Thermostat X8VMC8B (Black, no sensor) | 24 VAC systems up to 2H/2C, or heat pumps with electric backup, where a doorbell view or room sensors appeal | Free C-wire adapter voucher included, per the manual and listing | Maker page stage counts conflict with the manual and listing |
| Honeywell Home X7S Smart Thermostat X7SMC4B (Black) | 24 VAC systems up to 2H/2C, or heat pumps with electric backup, where room sensors and presence sensing appeal | Radar presence sensing and up to 20 room sensors, per the manual | Cannot control humidifiers, dehumidifiers or ventilators, per the manual |
| Honeywell Home X7B Smart Thermostat X7BWF1W (White) | 24 VAC systems up to 2H/2C, or heat pumps with electric backup, where room sensors are not needed | Same stage support as the X7S, agreed by manual, maker page and listing | No room sensor support and no radar presence sensing, per the manual |
| Sensi Touch Smart Thermostat ST75 (Black) | 24 VAC systems with a C wire, including 2-stage and heat pump set-ups, where humidity control matters | UPC matches Copeland's page, which publishes a full spec block | C wire required on every compatible system type |
| Aqara Thermostat Hub W200 SRT-A06E | 24 VAC systems up to 2H/2C, or heat pumps with up to 2 aux stages, in homes using Aqara, Matter or Thread devices | Acts as a Zigbee hub, Matter controller and Thread border router | C-wire adapter is sold separately; without power it will not turn on |
| Honeywell Home ElitePRO S1200 Smart Thermostat THX1200B6 (Black) | Professionally installed systems up to 4H/2C heat pump or 3H/3C conventional, with IAQ equipment | Supports up to 4H/2C heat pump or 3H/3C conventional systems | Trade product: warranty may be void if not professionally installed |
| Honeywell Home ElitePRO S1100 Smart Thermostat THX1100B4 (Black) | Professionally installed systems up to 4H/2C heat pump or 3H/3C conventional, with IAQ equipment | Supports up to 4H/2C heat pump or 3H/3C conventional systems | Trade product: warranty may be void if not professionally installed |
| Honeywell Home ElitePRO S1200 Smart Thermostat with Room Sensor YTHX1200W5 (White) | Professionally installed systems up to 4H/2C heat pump or 3H/3C conventional where one room needs priority | One wireless room sensor included for room priority | Trade product: warranty may be void if not professionally installed |
What to check before buying
The smart thermostat guides here check the wiring each model needs, starting with whether a C wire is required and whether an adapter is in the box. They list the systems and stage counts the maker supports, the Wi-Fi band and app or account needed, which sensors and air-quality controls each model has, and warranty terms, including those tied to professional installation.
- C wire and adapters. Most models here require a C wire. Guides report an adapter included, a voucher for one, adapters sold separately, and one model that runs on AA batteries instead. Check which applies before buying.
- Systems it can run. Several low-voltage models here rule out line-voltage baseboard heat, and some also rule out millivolt systems, while one line-voltage model works only with line-voltage heaters such as baseboards and sets minimum and maximum loads. Some heat pump setups support electric backup only.
- Stage counts by source. Count your heating and cooling stages. Guides report a maker page listing more stages than the manual, a model limited to one extra stage, and heat pump support capped at one compressor stage.
- Wi-Fi band and app. Several models are limited to 2.4 GHz Wi-Fi, and one maker page lists 5 GHz where its installation guides say 2.4 GHz only. The guides also record setup that needs the maker's app and an account, and a guide and page naming different apps.
- Warranty and install. Warranties in the guides run from one to five years. The five-year trade models may lose cover if not professionally installed, and one one-year warranty excludes removal and reinstallation costs.
This page collects 18 smart thermostat guides from Plain Buy Guides. Each guide covers one exact Amazon listing: the maker's published specifications, what the listing says is included, the fit and installation limits that decide whether it suits you, and the main caveat, with every source listed and dated. Nothing here is based on hands-on testing, and no guide promises a price or stock level.
In the table above, the Best for column says who each model suits, and the strength and caveat columns carry the first point each guide makes. Open a guide before buying to confirm the exact model, the included parts and any conflict between the listing and the maker's documents, which each guide reports rather than settles. Side-by-side pages put the published facts of two models from this category in one place.
Compare the published specs
The main figures stated in each smart thermostat guide on this page, side by side, with each guide's sources behind them. Units are as published; nothing here was measured by us.
A table scrolls sideways when it is wider than the screen. Select a column heading to sort.
— means the guide does not state that figure. n/a means the figure does not apply to that model. “or” means the guide states more than one figure, for example where two sources disagree, for different modes or versions, or where a kit includes two tools; open the guide to see which applies. † means the guide reports that another source gives a different figure, or doubts the figure; open the guide. Only single figures in the column’s unit, with no mark, word or note in brackets, are sorted and counted below.
By the numbers
These cover only the 18 smart thermostats on this site, not the whole market. Ranges use the figures the guides state; the lowest and highest link to their guides, and the median is the middle of those figures. A model whose figure is missing, not applicable, more than one, marked, in words, in another unit or qualified in brackets is left out of that line.
- C wire across our 18 smart thermostats: Required: 12; Not required (some systems may need one): 1; Required for some systems: 2; Required (or sold adapter): 1; not stated, not applicable or more than one: 2.
- Wi-Fi across our 18 smart thermostats: 2.4 + 5 GHz: 10; 2.4 GHz only: 6; not stated, not applicable or more than one: 2.
Read the full C-Wire Check buying guide (c-wire-check.pages.dev).
- Sensi Smart Thermostat ST55
Sensi ST55 guide: C-wire requirements by system, HomeKit unit checks, 20–30 VAC limits, 2.4GHz Wi-Fi and the three-year warranty.
- Google Nest Thermostat (Charcoal)
Google Nest Thermostat guide: the stages Google lists, when a C wire may be needed, AAA backup cells, the plates sold separately, and the model code Google prints.
- Mysa Smart Thermostat V2 for Electric Baseboard Heaters (BB.2.0.01.NA-US)
Mysa for Electric Baseboard Heaters V2 guide: the 1,900W and 3,800W load ceilings, the 250W floor, what line-voltage wiring it needs, and a five-year warranty.
- Sensi Touch 2 Smart Thermostat ST76 (Black)
Sensi Touch 2 ST76 guide: the C wire every system needs, stages up to 4H/2C heat pump, conflicting Wi-Fi band claims, optional room sensors and the warranty.
- Sensi Lite Smart Thermostat ST25 (Black)
Sensi Lite ST25 guide: when Sensi says you need a C wire, the one-extra-stage limit, 2.4 GHz Wi-Fi, Sensi app and account setup, and the three-year warranty.
- Honeywell Home RTH6580WF Wi-Fi 7-Day Programmable Thermostat (White)
Honeywell Home RTH6580WF Wi-Fi 7-day thermostat: the C-wire requirement, which systems it runs, 2.4 GHz setup, Total Connect Comfort and the 1-year warranty.
- Honeywell Home T9 Smart Thermostat with 1 Room Sensor RCHT9610WFSW2003
Honeywell Home T9 with one room sensor (RCHT9610WFSW2003): the included C-wire adapter, sensor range and priority, systems it will not run, and the 2-year warranty.
- Honeywell Home T5 Smart Thermostat RTH8800WF2022
Honeywell Home T5 (RTH8800WF2022) guide: the required C wire, 2.4 GHz-only Wi-Fi, stage limits, what still works offline, which app it uses and the 2-year warranty.
- Honeywell Home X2S Smart Wi-Fi Thermostat RTH2SMC/N (White)
Honeywell Home X2S (RTH2SMC) specs: C wire at 24 VAC, 2 heat/2 cool, heat pumps with one compressor stage, Matter, 2-year warranty, install guide link.
- Honeywell Home X2P Programmable Thermostat RTH20B (White)
Honeywell Home X2P (RTH20B): a 1-heat/1-cool thermostat on two AA batteries, the maker's conflicting schedule lists, heat pump caveats and the 1-year warranty.
- Honeywell Home X8S Smart Thermostat X8VMC8B (Black, no sensor)
Honeywell Home X8S (X8VMC8B, black) guide: the stage-count conflict on the maker page, electric-only heat pump backup, the C-wire voucher, doorbell view, warranty.
- Honeywell Home X7S Smart Thermostat X7SMC4B (Black)
Honeywell Home X7S (X7SMC4B, black) guide: radar presence sensing, room sensors, what X7 cannot control, electric-only heat pump backup, C wire and warranty.
- Honeywell Home X7B Smart Thermostat X7BWF1W (White)
Honeywell Home X7B (X7BWF1W, white) guide: what the X7B leaves out versus the X7S, the radar-sensor conflict, electric-only heat pump backup, C wire and warranty.
- Sensi Touch Smart Thermostat ST75 (Black)
Sensi Touch ST75 guide: the C-wire requirement, 2.4 GHz setup through the Sensi app, stage and humidity control, what works at the wall, and the 3-year warranty.
- Aqara Thermostat Hub W200 SRT-A06E
Aqara Thermostat Hub W200 (SRT-A06E) guide: the C-wire adapter you may need, terminals it cannot use, heat pump limits, the built-in Zigbee and Thread hub and radar.
- Honeywell Home ElitePRO S1200 Smart Thermostat THX1200B6 (Black)
Honeywell ElitePRO S1200 (THX1200B6, black) guide: a trade product whose warranty may be void without pro install, 4H/2C staging, IAQ control, Redlink and C wire.
- Honeywell Home ElitePRO S1100 Smart Thermostat THX1100B4 (Black)
Honeywell ElitePRO S1100 (THX1100B4, black) guide: a trade thermostat whose warranty may be void without pro install, 4H/2C staging, IAQ control, Redlink and power.
- Honeywell Home ElitePRO S1200 Smart Thermostat with Room Sensor YTHX1200W5 (White)
Honeywell ElitePRO S1200 with room sensor (YTHX1200W5, white): pro-install warranty condition, the included Redlink sensor, 4H/2C staging, IAQ control and C wire.