Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen) vs Sensi Lite Smart Thermostat ST25 (Black)
These are side-by-side facts taken from each product guide: published specifications, strengths and caveats as their sources state them. This page is not a test, a ranking or a verdict about which model is better.
Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen)
Multi-stage 24V systems run through the Google Home app, in homes with or without a C wire
Google's top thermostat, bundled with one room sensor, a trim plate and a steel plate. The maker lists up to three stages of heat and cool, three-stage heat pumps with aux and emergency heat, plus humidifier, dehumidifier and ventilation terminals. Power Sharing means no C wire in most homes, and control runs through Google Home and Matter.
Published specifications
- Maker: most 24V systems; heating and cooling 1-3 stages; heat pump to 3 stages with AUX, AUX2 and E
- Maker: star connector takes only one of W3, Y3, G3, E, HUM or DEHUM; AQ+/AQ- limited to Y3 or VENT/HUM/DEHUM
- Maker: Power Sharing works with or without a C wire; under 1% of homes may need a C wire or Nest Power Connector
- Maker: Wi-Fi 802.11n on 2.4 GHz and 5 GHz; works with Google Home and Matter; Google Home app required to set up
- Maker: 3.9 in diameter, 1.1 in deep, 5.7 oz; 2.7-inch 600x600 circular display; Soli, temperature, humidity, light sensors
- Warranty: Google Store lists 2 years retail and 5 years for HVAC pros; the listing's warranty PDF says one year
Strengths
- Maker publishes the exact stages and terminals, including three-stage heat, cool and heat pump support
- Trim plate, steel plate and a Nest Temperature Sensor are all in the box
- Works without a C wire in over 99% of homes by Google's own figure, and takes 2.4 GHz or 5 GHz Wi-Fi
Caveats
- Setup requires the Google Home app and account; Alexa or Apple control goes through Matter and may need a third-party hub
- Warranty length differs between Google's spec page and the warranty PDF on the listing, and covers authorised resellers only
- The extra terminals are shared: you cannot use W3, Y3, G3, E, HUM and DEHUM all at once
Read the full Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen) guide
Sensi Lite Smart Thermostat ST25 (Black)
Single-stage or one-extra-stage 24 VAC systems on a 2.4 GHz network
Copeland's Sensi Lite thermostat, confirmed by matching UPC. It handles 1H/1C, 1H/2C or 2H/1C conventional systems and 2H/1C heat pumps. Copeland and the listing agree that heat-only, cool-only and heat pump systems need a C wire. Setup requires the Sensi app and an account; the warranty is three years for DIY or pro installs.
Published specifications
- Maker: stages 1H/1C, 1H/2C or 2H/1C conventional; heat pump 2H/1C; 3-wire zone heat
- Maker and listing: C wire required for heat-only, cool-only and heat pump systems
- Maker: 24 VAC, 20-30 Vac rating; hardwire with power stealing; 2 x AAA included
- Guide: Wi-Fi 2.4 GHz only; Sensi app and account required; Alexa, Google Assistant, SmartThings
- Maker: 5.07 x 3.13 x 0.88 in; 7-day schedule, 8 periods a day; geofencing; keypad lockout
- Maker warranty table: 3 years, DIY or professional install
Strengths
- Listing and maker agree on exactly which systems need a C wire
- Three-year warranty applies whether you or a contractor installs it
- UPC matches Copeland's product page, which publishes a specification block
Caveats
- Only one extra stage: no 2H/2C, and no two-stage heat pump support
- Heat pump, heat-only and cool-only systems need a C wire
- Requires the Sensi app, an account and a 2.4 GHz network to set up
Read the full Sensi Lite Smart Thermostat ST25 (Black) guide
How to choose between them
Choose the Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen) if your situation matches: Multi-stage 24V systems run through the Google Home app, in homes with or without a C wire. Its main caveat: Setup requires the Google Home app and account; Alexa or Apple control goes through Matter and may need a third-party hub.
Choose the Sensi Lite Smart Thermostat ST25 (Black) if your situation matches: Single-stage or one-extra-stage 24 VAC systems on a 2.4 GHz network. Its main caveat: Only one extra stage: no 2H/2C, and no two-stage heat pump support.
Both entries repeat what each guide records. Confirm the model, included parts and availability on the current listing before ordering.
Primary sources
- Google Store tech specs and wiring compatibility, Nest Learning Thermostat (4th gen) Source for Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen)
- Google Consumer Hardware Limited Warranty PDF supplied with the Amazon listing Source for Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen)
- Google Nest compatibility checker named on the Google Store specs page and in the listing Source for Google Nest Learning Thermostat (4th gen) with Nest Temperature Sensor (2nd gen)
- Copeland product page and specifications for Sensi Lite Smart Thermostat ST25 Source for Sensi Lite Smart Thermostat ST25 (Black)
- Sensi Lite installation guide R-5664 (ST25 series) supplied with the Amazon listing Source for Sensi Lite Smart Thermostat ST25 (Black)
- Copeland Sensi warranty table by model Source for Sensi Lite Smart Thermostat ST25 (Black)
Primary sources checked .