Emerson Sensi ST55
Score: 72/100
ecobee3 Lite
Score: 82/100Rankings
The Ecobee3 Lite offers a budget-friendly 3.5-inch touchscreen, built-in sensors and broad HomeKit, Alexa and Google Assistant support. Its reliance on a C-wire or power extender kit and modest display resolution may deter users seeking higher-end visuals. Best suited for cost-conscious owners of 24 V HVAC systems who value multi-room sensing.
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 | | |
|---|---|---|
3 yearsbest | 3 yearsbest | |
5 inchbest | 3.5 inch | |
| ↓ lower better | 0.386 kgbest | 2.268 kg |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | | |
|---|---|---|
General(1) | ||
HVAC Compatibility | Various (single to multi-stage) | Approximately 95% of 24V systems |
Connectivity(1) | ||
Smart Home Integration | Alexa, Google Assistant, Apple HomeKit, Samsung SmartThings | Siri, Google Assistant, Samsung SmartThings, IFTTT, Alexa |
Power & Installation(1) | ||
Power Source | 20-30 VAC | Hardwired 24V |
Display(1) | ||
Screen Size (inch) | 5 inch | 3.5 inch |
Build & Design(2) | ||
Device Weight (kg) | 0.386 kg | 2.268 kg |
Device Dimensions (H×W×D) (mm) | 25.4×149.35×95.25 mm mm | 102.9x102.9x21.4 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.
Industry analysts and the manufacturer emphasize the Ecobee3 Lite's strong energy-efficiency credentials, easy installation with the optional Power Extender Kit, and its broad smart-home ecosystem support, positioning it as a cost-effective solution that can still achieve notable savings of around 23 % per year.
