Which one fits which system
Both are smart wifi thermostats from the same table; what separates them is c wire (maker), works with. Pick by the one your wiring and system need, using the rows below.
The central trade-off
C wire (maker). The Sensi ST25 Smart Thermostat lists COMMON WIRE REQUIREMENTS: Designed to work without a C-wire in most homes, but for some sys; the Sensi ST75 Smart Thermostat lists Common wire (c-wire) is required.
Works with. The Sensi ST25 Smart Thermostat lists Amazon Alexa, Google Assistant, Hand Control, SmartThings; the Sensi ST75 Smart Thermostat lists Amazon Alexa, Apple HomeKit, Google Assistant, SmartThings, Vera.
Statement by statement
| Statement | Sensi ST25 Smart Thermostat | Sensi ST75 Smart Thermostat |
|---|---|---|
| C wire (maker) | COMMON WIRE REQUIREMENTS: Designed to work without a C-wire in most homes, but for some sys | Common wire (c-wire) is required |
| Heat pump (maker) | Not stated by the maker | Not stated by the maker |
| Stages (maker) | Not stated by the maker | Not stated by the maker |
| Systems (maker) | Works with the HVAC equipment found in most homes | Works with the HVAC equipment found in most homes |
| Sensors | Not stated by the maker | Not stated by the maker |
| Works with | Amazon Alexa, Google Assistant, Hand Control, SmartThings | Amazon Alexa, Apple HomeKit, Google Assistant, SmartThings, Vera |
Values are the makers' published specifications. "Not stated" means the maker doesn't publish it.
Which should you choose?
Choose the Sensi ST25 Smart Thermostat if
- C wire (maker): COMMON WIRE REQUIREMENTS: Designed to work without a C-wire in most homes, but for some sys
- Works with: Amazon Alexa, Google Assistant, Hand Control, SmartThings
Choose the Sensi ST75 Smart Thermostat if
- C wire (maker): Common wire (c-wire) is required
- Works with: Amazon Alexa, Apple HomeKit, Google Assistant, SmartThings, Vera