Sensi Smart Thermostat ST55 Review (2026): Worth It?
The Sensi ST55 is an Energy Star certified Wi-Fi thermostat built for do-it-yourself installation, with physical buttons, a built-in level and app guidance, and support for Alexa, Apple HomeKit, Google Assistant and SmartThings. It is listed at $99.99, 23% below its list price of $129.99, and rated 4.4 out of 5 from 23,104 Amazon ratings. Our score: 8.4 out of 10.
Original price was: $129.99.$99.99Current price is: $99.99.
Sensi Smart Thermostat ST55 Review: A DIY Smart Thermostat That Usually Skips The C-Wire
The Sensi ST55 is an Energy Star certified Wi-Fi thermostat built for do-it-yourself installation, with physical buttons, a built-in level and app guidance, and support for Alexa, Apple HomeKit, Google Assistant and SmartThings. It is listed at $99.99, 23% below its list price of $129.99, and rated 4.4 out of 5 from 23,104 Amazon ratings. Our score: 8.4 out of 10.
This review is research-based. We did not physically test this product; specifications, ratings and prices are taken from the live Amazon listing on 17 October 2026. Amazon prices change often, so check the current price before you buy. It is part of our Smart Home section.
Key Specifications
| Specification | Published value |
|---|---|
| Reviewed model | Sensi Smart Thermostat ST55 |
| Product | Sensi Smart Thermostat, Wi-Fi, DIY, Alexa, Energy Star Certified, ST55 |
| Price at review | $99.99 (down 23% from a list price of $129.99), checked 17 October 2026 |
| Owner rating | 4.4 out of 5 from 23,104 ratings |
| Model | ST55 |
| Controls | Physical buttons plus app |
| Smart home | Amazon Alexa, Apple HomeKit, Google Assistant, SmartThings, Vera |
| C-wire | Not required in most applications (per listing) |
| Certification | Energy Star |
| Features | Scheduling, remote access, usage reports, filter reminders |
| Size | 1 x 5.88 x 3.75 inches |
| Blue Rays score | 8.4 out of 10 |
What Stands Out About The Sensi Smart Thermostat ST55
- Usually installs without a C-wire
- Works with all the major smart-home platforms, including HomeKit
- Fits the footprint of a traditional thermostat, so no wall patching
- Sensi says it will not sell your personal information
- 23,000-plus ratings at 4.4 stars
Limitations
- Basic monochrome display, not a touchscreen
- The "save about 23%" figure is Sensi's own estimate
- No room sensors in the box
- Some systems will still need a C-wire
Who Should Buy This Sensi Smart Thermostat?
Renters and homeowners in older houses without a C-wire, and Apple HomeKit users who want a thermostat that is simple to install.
The Verdict
The easiest smart thermostat to recommend for a DIY install. Broad platform support and the no-C-wire design solve the two most common problems buyers hit.
Sensi Smart Thermostat ST55 — Frequently Asked Questions
Does the Sensi ST55 need a C-wire?
According to the listing, a common wire is not required in most applications.
Does Sensi work with Apple HomeKit?
Yes. The listing names Amazon Alexa, Apple HomeKit, Google Assistant, SmartThings and Vera.
Check the Sensi Smart Thermostat ST55 price on Amazon →
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