Choose ecobee Premium or Sensi ST55 by Wiring and Room-Sensor Fit
Check wiring first, then decide whether a remote reading from another room is part of the purchase. ecobee Premium includes a PEK and one SmartSensor. Sensi says ST55 does not need a C-wire in most conventional systems but requires one for heat-only, cool-only, heat-pump, and zone systems; Sensi Room Sensors are compatible only with Touch 2 models, not ST55.
Published by Pickoryx · Published 2026-10-15
Source checked 2026-10-15 11:12 UTC
Products compared
Product A · ASIN B09XXS48P8
ecobee Smart Thermostat Premium (EB-STATE6-01)
Last observed offer
$242.48 List Price: $259.99
Per listed package.
Offer eligibility must be confirmed on Amazon.
Checked 2026-10-19 19:16 UTC. Price and availability may change.
Product B · ASIN B01NB1OB0I
Sensi Smart Thermostat (ST55)
Last observed offer
$98.00 List Price: $129.99
Per listed package.
Offer eligibility must be confirmed on Amazon.
Checked 2026-10-19 18:17 UTC. Price and availability may change.
Pickoryx may earn a commission from qualifying purchases through the paid Amazon links on this page, at no added cost to you.
The buying question
Which exact thermostat fits the home's wiring, and does the buyer need a manufacturer-supported remote room sensor?
ecobee Premium includes a Power Extender Kit and one SmartSensor. Sensi ST55 follows Sensi Smart's wiring guidance, including a C-wire requirement for some system types; Sensi lists its Room Sensors as compatible only with Touch 2 models, not ST55. Check the home's wiring and equipment with the manufacturers' compatibility tools.
Quick verdict
Choose ecobee Smart Thermostat Premium (EB-STATE6-01) if
- You want the SmartSensor included with ecobee Premium, and ecobee's compatibility check supports your system.
- Your system passes ecobee's compatibility check and the included PEK may address an eligible installation without a C-wire.
Choose Sensi Smart Thermostat (ST55) if
- Your system is a conventional heating-and-cooling setup that Sensi identifies as not requiring a C-wire, and the exact compatibility check agrees.
- You want Sensi Smart's published thermostat features and do not require Sensi Room Sensors with ST55.
When the recommendation changes
- If the existing system is heat-only, cool-only, a heat pump, or zoned, Sensi says a C-wire is required; check the exact wiring before choosing ST55.
- If you want Sensi Room Sensors, choose a listed compatible Touch 2 model instead of ST55, or consider ecobee Premium if its SmartSensor and system compatibility fit your needs.
The differences that matter
Installation Power Path And Wiring Gate
ecobee Smart Thermostat Premium (EB-STATE6-01)
ecobee lists wired 24VAC through C and Rc and says the included Power Extender Kit can power the thermostat without running a fifth wire. It describes compatibility as most 24VAC equipment, subject to its compatibility checker.[1]
What this changes: The useful comparison is the documented power path for the buyer's actual system. The PEK is not a universal compatibility guarantee, and Sensi's C-wire exceptions still apply. Use each manufacturer's checker with the equipment type and existing wire labels before ordering.[1, 2, 3]
External Room Temperature Sensing Workflow
ecobee Smart Thermostat Premium (EB-STATE6-01)
The exact Premium product page lists one SmartSensor in the box and describes it as a remote sensor for another room.[1]
Sensi Smart Thermostat (ST55)
Sensi says its Room Sensors are compatible only with Touch 2 thermostats (ST76 and 1F96U series). Sensi's installation guide maps ST55 to the Sensi Smart thermostat family, so Sensi Room Sensors are not compatible with ST55. This statement applies to Sensi Room Sensors only.[4, 2]
What this changes: If a manufacturer-supported reading from another room is required, ecobee Premium includes one SmartSensor. Sensi Room Sensors are not an option with ST55; Sensi lists them only for its Touch 2 models. This is a feature-fit distinction, not a claim about comfort or temperature outcomes.[1, 4, 2]
Best for your routine
Buyer who wants one remote room sensor included with the thermostat
Best fit: ecobee Smart Thermostat Premium (EB-STATE6-01)
Based on listed features, not comparative testing.
ecobee lists one SmartSensor in the exact Premium box contents. Sensi says its Room Sensors are compatible only with Touch 2 models, not ST55. This supports a feature-fit choice, not a promise about comfort or heating results.
Buyer whose conventional heating-and-cooling wiring fits Sensi's published C-wire guidance
Best fit: Sensi Smart Thermostat (ST55)
Based on listed features, not comparative testing.
Sensi says a common wire is not required for most conventional heating-and-cooling systems. The exact installation still needs to pass Sensi's system checker.
Value and trade-offs
One or both observed offers have eligibility conditions, so no unrestricted price difference is shown.
A higher current offer for Premium would need to be justified by this buyer's use of the included SmartSensor and a PEK-supported wiring path; current offers were not assessed.
Current offers and their terms were not assessed. Compare current prices before purchase; there is not enough price history here to recommend buying now or waiting.
Limitations
- No hands-on installation or HVAC compatibility testing was performed. Identify the system type and existing wire labels, then run the manufacturers' compatibility checks.
- Sensi lists its Room Sensors as compatible only with Touch 2 models (ST76 and 1F96U series); ST55 is mapped to Sensi Smart. This compatibility statement covers Sensi Room Sensors only.
- Current prices and offer terms, availability, rebates, warranty coverage for a particular offer, and installation service were not assessed.
Questions shoppers ask
Does the Sensi ST55 always need a C-wire?
No. Sensi says its C-wire is not required for most conventional heating-and-cooling systems, while heat-only, cool-only, heat-pump, and zone systems require one. Check the exact system with Sensi before purchase.
Does the Sensi ST55 work with Sensi Room Sensors?
No. Sensi says its Room Sensors are compatible only with Touch 2 models (ST76 and 1F96U series). Sensi maps ST55 to the Sensi Smart family. ecobee Premium includes one ecobee SmartSensor.
Methodology and sources
The models are compared on their documented power and C-wire paths and on Sensi's explicitly stated Room Sensor compatibility for the ST55 model family. No home-specific compatibility, installation ease, or temperature outcome is inferred.
AI-assisted research organized the model-specific manufacturer information; Pickoryx did not perform installation or product testing.
View 4 sources
- 1.Smart Thermostat Premiumecobee · Official specifications · Source checked 2026-10-15 10:24 UTC
Evidence used on this page
- Features and specifications: power method and compatibility (lines 630-635, 703-705, 760-764); What's in the box (808-824); SmartSensor overview (196-222).: The exact US Premium page lists a SmartSensor and PEK in the box, describes wired 24VAC through C/Rc and PEK powering without a fifth wire, and limits compatibility language to most 24VAC equipment with a compatibility checker.
- 2.Sensi smart thermostat InstallationSensi / Copeland · Official specifications · Source checked 2026-10-15 10:24 UTC
Evidence used on this page
- Step 1 model mapping (26-30) identifies ST55 series; Step 3 C-wire and compatibility instructions (49-51).: Sensi maps ST55 series to its Sensi Smart installation flow and says a C-wire is required for heat-only, cool-only, and heat-pump applications; it directs buyers to compatibility guidance.
- 3.Sensi Smart Wi-Fi ThermostatSensi / Copeland · Official specifications · Source checked 2026-10-15 10:24 UTC
Evidence used on this page
- Model row maps ST55/ST55U to Sensi Smart; C-wire row and footnote give conventional and exception cases (149-167).: The official US comparison maps ST55 to the Sensi Smart column and states C-wire requirements with a system-type footnote. Room Sensor compatibility is supported separately by Sensi’s explicit compatibility page.
- 4.Room Sensor CompatibilitySensi / Copeland · Official specifications · Source checked 2026-10-15 10:58 UTC
Evidence used on this page
- “Which thermostats are compatible with Sensi room sensors?” states only Sensi Touch 2 models are compatible; Touch 2 model list identifies ST76 and 1F96U series (lines 6-13).: Sensi explicitly states that only Touch 2 model thermostats are compatible with Sensi Room Sensors, naming ST76 and 1F96U series.