Emerson Sensi ST55
Score: 72/100
ecobee Smart Thermostat Premium
Score: 86/100Rankings
Ecobee Smart Thermostat Premium combines a 4-inch high-resolution touchscreen with built-in air-quality monitoring, smoke detection, and SmartSensor room control. It demands a C-wire (or Power Extender Kit) and carries a higher price point. It excels for users desiring premium features and robust performance.
Emerson Sensi ST55 provides a 5-inch LED touchscreen, broad smart-home compatibility, and geofencing-driven energy savings, all at an affordable price. Limitations include the need for a C-wire, 2.4 GHz-only Wi-Fi, and lack of built-in room sensors. Ideal for DIY homeowners seeking a versatile, budget-friendly thermostat.
| Attribute | | |
|---|---|---|
— | 0.5 °Cbest | |
3 yearsbest | 3 yearsbest | |
5 inchbest | 4 inch | |
| ↓ lower better | 0.386 kg | 0.249 kgbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | | |
|---|---|---|
General(1) | ||
HVAC Compatibility | Various (single to multi-stage) | 24V |
Connectivity(1) | ||
Smart Home Integration | Alexa, Google Assistant, Apple HomeKit, Samsung SmartThings | Siri, Alexa, Google Assistant |
Power & Installation(1) | ||
Power Source | 20-30 VAC | C‑wire |
Display(2) | ||
Display Type | LED touchscreen | Touchscreen |
Screen Size (inch) | 5 inch | 4 inch |
Build & Design(2) | ||
Device Weight (kg) | 0.386 kg | 0.249 kg |
Device Dimensions (H×W×D) (mm) | 25.4×149.35×95.25 mm mm | 103.9×103.9×25.9 mm mm |
Products in the top-left offer the best value (high score, low price).
Professional reviewers commend the Sensi ST55 for its straightforward DIY installation, ENERGY STAR efficiency and the claimed 23% energy savings, as well as its compliance with Title 24 and robust smart-home integration. However, they point out the need for a c-wire to unlock full functionality and the limitation to a 2.4 GHz Wi-Fi band.
Homeowners and renters alike praise the thermostat's quick setup, remote app control, energy-saving reports, and reliable fan circulation. Recurring complaints focus on occasional Wi-Fi drops, the necessity of a c-wire for some systems, and the lack of a built-in room sensor or precise humidity control.
