No C Wire Options
Compare no-C-wire smart thermostats by power method: included adapters and extenders, battery power, and the line-voltage systems to rule out.
Emerson ST55 ST55 Wi-Fi Smart Thermostat with Wall Plate
Features
- Editors Choice Best Value
- Saves about 23% on HVAC energy
- ENERGY STAR certified
- Works with Alexa
- Most install in 30 minutes or less
- Extensive HVAC compatibility
- Includes wall plate
- Covers marks and holes
General specs
- Brand: Emerson
- Model: ST55
- Seller: Retailer
- ID: B08F7XZL3L
- Accessory: F61-2663 Wall Plate
- Product Name: Sensi Wi-Fi Smart Thermostat ST55
- Compatibility: Most HVAC equipment with C-wire
- Energy Savings: Up to 23% on HVAC energy
- Thermostat Type: Programmable, Wi-Fi enabled
- Wall Plate Color: White
- Installation Time: 30 minutes or less
- Wall Plate Purpose: Covers marks, holes, or other wall imperfections
- Not Compatible With: Sensi Touch models ST75 and ST75W
- Energy Certification: ENERGY STAR Certified
- Wall Plate Designed For: Sensi Wi-Fi thermostat models ST55 and 1F87U-42WF
- Smart Home Compatibility: Alexa
- First listed by seller: May 20, 2026
If you are interested in more details, you can find full information on the seller's page.
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Shipping options
Delivery to 
United States
United States
Available
Take control of your home's comfort and energy savings with the Emerson Sensi Wi-Fi Smart Thermostat. Ideal for busy homeowners who want an easy DIY upgrade, this thermostat helps you save about 23% on HVAC energy costs using smart features like geofencing, flexible scheduling, and remote access. Most installations take under 30 minutes with the built-in level and step-by-step app guidance. It works with most HVAC systems, requiring a C-wire for heat-only, cool-only, and heat pump setups.
The included F61-2663 wall plate is designed exclusively for Sensi models ST55 and 1F87U-42WF, covering unsightly marks or holes from old thermostats. Enjoy seamless integration with Alexa for voice control. This ENERGY STAR certified thermostat is a smart choice for eco-conscious users seeking savings and convenience.
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| Brand | Emerson | Honeywell Home | vine | Wyze | Amazon Renewed | Honeywell |
| Model | ST55 | RCHT8612WF | TJ-225B | ST76 | RTH9580WF | |
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| Price | €77.18 | €136.54 | €47.29 | €191.84 | €121.78 | €133.04 |
| Seller | Retailer | Retailer | Retailer | Retailer | Retailer | Retailer |
| Update | May 20, 2026 | Jun 24, 2026 | May 29, 2026 | Jun 24, 2026 | May 20, 2026 | Jun 24, 2026 |
| Compatibility | Most HVAC equipment with C-wire | Most residential heating and cooling systems | Alexa, Google Assistant | 90% home systems | Apple iOS, Android | |
| Connectivity | Wi-Fi | Wi-Fi | Wi-Fi | |||
When this device makes sense
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