Smart thermostats remain one of the best smart home upgrades for energy savings, automation, and comfort. With the Honeywell Home X2S Smart Thermostat (RTH2CWF), Resideo has created a highly affordable, Matter-certified smart thermostat that’s modern, simple to install, and compatible with most HVAC systems. At just $79.99 MSRP, the X2S brings premium ecosystem support—such as Google Assistant, Amazon Alexa, and Apple Home (via Matter)—to an entry-level price.

We tested the X2S extensively for several months at our GearBrain test home, including installation, daily use, scheduling, ecosystem connections, and long-term stability. Here is everything you need to know before you buy.

What Is the Honeywell Home X2S Smart Thermostat?

The X2S is Resideo’s new Wi-Fi-enabled smart programmable thermostat, designed for homeowners who want modern features—mobile control, scheduling, energy savings, and voice assistant compatibility—without spending $150–$250 on premium models.

Key capabilities include:

• Matter Certified, supporting Google Assistant, Amazon Alexa, and Apple HomeKit.
• Wi-Fi control via the First Alert by Resideo app.
• Multiple scheduling options: 5-1-1, 5-2, 7-day, or 1-week.
• Compatibility with most 24V HVAC systems (up to 2 Heat/2 Cool conventional; up to 2 Heat/1 Cool heat pump).
• ENERGY STAR certification and the ability to connect to local utility demand-response programs.

It does not work with electric baseboard heat (120–240V), and it does not support S-terminal sensors or U-terminal relays—essential details buyers should consider before upgrading.

The X2S is Resideo’s next-generation replacement for the long-popular Honeywell Home RTH6580 WiFi 7-Day Programmable Thermostat, adding:

• Matter Certification for multi-ecosystem control
• Upgraded Wi-Fi performance
• A cleaner, modern interface
• A redesigned app experience via the First Alert by Resideo app
• ENERGY STAR certification
• A universal mounting system (UWP) included in the box

Unlike Honeywell’s higher-end T9 and T10 thermostats, the X2S does not support room sensors and is designed as a budget-friendly smart thermostat for single-zone homes.

New! Honeywell Home Smart Thermostat, Conventional/Heat Pump Compatibility, WiFi Thermostat for Home, X2S, White

List Price: $79.99

New From: $68.50 in Stock

Used From: $57.66 in Stock

Installation and Universal Mounting System: Check the Box Carefully

One of the best surprises of the X2S is how simple installation is—especially for homeowners who already have a modern Honeywell Home thermostat installed.

Our test home previously used the Honeywell Home T9, which already uses the UWP (Universal Wall Plate) mounting system. That meant:

1. We removed the T9’s faceplate
2. Snapped the X2S onto the same UWP mount
3. Installation was complete in seconds

✔ The X2S DOES include the UWP mount — but it may be tucked away

When we first opened our X2S review unit, we did not see the UWP mount and assumed it was not included. It turns out the UWP mounting system was tucked inside the packaging, easy to overlook if you don’t dig to the bottom.

Buyers should fully check the box before assuming it’s missing. Resideo confirmed the UWP mounting system is included with every X2S.

If you ever do need to buy the mount separately—for replacing a damaged one or installing multiple thermostats—the UWP system typically retails around $10–$15, depending on the seller. But again, the thermostat always ships with one.

✔ If you already have a UWP plate

Installation takes under 2 minutes—no wiring changes required.

✔ If you do not have a C-Wire

Like most smart thermostats, the X2S requires a C-wire. If you don’t have one:

• You may need a C-wire adapter (sold separately), or
• An HVAC technician can run a new wire

This is standard with almost all modern smart thermostats in this price range.

App Setup: Use the First Alert by Resideo App (Not the Old Resideo App)

use First Alert by Resideo app instead of the old Resideo app.GearBrain

When we tried to pair the X2S with the Resideo app, the thermostat didn’t appear—because Resideo is transitioning all new devices (and some existing ones) to the First Alert app.

✔ Products now using the First Alert by Resideo App

• Honeywell X2S Smart Thermostat
• Honeywell Home T9 Smart Thermostat with Sensor
• Honeywell Home T10+ Pro Smart Thermostat
• Honeywell Home T5 Smart Thermostat
• Honeywell Home T6 Pro Smart Thermostat
• First Alert L Series (L1, L2, L5)
• First Alert VX3 HD Outdoor Camera
• First Alert VX1 HD Video Doorbell
• First Alert SC5 Smart Smoke & CO Alarm

✔ Products still using the Resideo App

• Honeywell Home T9 Smart Thermostat with Sensor
• Honeywell Home T10+ Pro Smart Thermostat
• First Alert L1 Water Leak and Freeze Detector
• Honeywell Home C2 WiFi Security Camera

(Yes, the T9 and T10 appear on both lists. Resideo is transitioning support, and their compatibility varies depending on when a user initially set up the device.)

Resideo has documentation on migrating to the new app, and the transition is ongoing across its product lines.

Compatibility: Check Your HVAC System Before Buying

The X2S supports most standard 24V home HVAC systems.

✔ Supported:

• Up to 2 Heat / 2 Cool conventional
• Up to 2 Heat / 1 Cool heat pumps (with electric backup)
• Hot water heat
• Forced air (gas, oil, electric)

✘ Not supported:

• Electric baseboard heating (120–240V)
• S-terminal wired sensors
• U-terminal relays
• Room sensors (T9/T10 sensors do not work with X2S)

In our tests, existing T9 room sensors did not connect to the X2S. Resideo confirmed the X2S is not designed for sensor support and that the next gen Honeywell Home smart thermostat will support optional smart sensors.

This underscores that the X2S is designed as a straightforward smart upgrade, not a multi-room sensing system.

Smart Home Integration

Devices compatible with Honeywell Home X2S Smart Thermostat GearBrain

• Amazon Alexa
• Google Assistant
• Apple Home (via Matter)
• First Alert by Resideo app

Matter support ensures long-term interoperability and makes the thermostat flexible for households switching smart home platforms.

Both Alexa and Google Assistant voice commands worked instantly in testing.

New! Honeywell Home Smart Thermostat, Conventional/Heat Pump Compatibility, WiFi Thermostat for Home, X2S, Gray

List Price: $79.98

New From: $45.99 in Stock

Used From: $42.00 in Stock

Daily Performance: What We Loved

Throughout testing, the X2S delivered fast, stable, and reliable performance.

✔ Adjustable screen brightness

The display is crisp, easy to read, and offers brightness controls—great for nighttime use.

✔ Easy on-device programming

The thermostat allows quick temperature changes, scheduling, HVAC mode switching, and fan settings using the physical interface.

✔ ENERGY STAR Certified

Auto-away, scheduling, and smart recovery were accurate and helped reduce energy consumption.

✔ Supports both 2.4 GHz and 5 GHz Wi-Fi

This eliminates connectivity headaches common in older smart thermostats.

✔ Simple, clean design

The slim white profile blends easily into most walls.

✔ Affordable—very

Even with the cost of adding a C-wire adapter (if needed), the total system cost is still below most competitors.

What’s Missing in the X2S

The X2S is intentionally simple, and with its low price comes a few limitations:

• No room sensors
• No S or U terminal support
• Not compatible with high-voltage baseboard systems
• No geofencing (only scheduling + auto-away)
• No advanced automation features found in T9/T10

But for buyers wanting a straightforward smart thermostat, these omissions help keep the cost low.

X2S vs. Honeywell Home WiFi 7-Day Programmable Thermostat (RTH6580)

✔ X2S improves on the older model with:

• Matter certification
• New First Alert by Resideo app support
• A clearer, more modern display
• ENERGY STAR certification
• Dual-band Wi-Fi
• Universal mounting system
• Better long-term ecosystem integration

✔ And importantly:

The X2S is designed as the direct replacement for the RTH6580.

✘ What the older model still has

• Slightly broader support for legacy HVAC wiring
• Sometimes lower street price during utility rebates

But the X2S is the clear upgrade path for most homeowners—especially those wanting smart home compatibility.

Summary

The Honeywell Home X2S Smart Thermostat is easily one of the best-value smart thermostats under $100. Between Matter support, easy installation—especially for existing Honeywell Home users—ENERGY STAR performance, and a clean, reliable interface, the X2S will appeal to budget-conscious homeowners who want modern smart home integration without complexity.

If you rely on room sensors, you’ll want to wait for the next gen Honeywell Home smart thermostat, but for most single-zone households, the X2S is an excellent upgrade and a strong replacement for the RTH6580.

And don’t forget to check the box carefully—your UWP mount is included.

New! Honeywell Home Smart Thermostat, Conventional/Heat Pump Compatibility, WiFi Thermostat for Home, X2S, Gray

List Price: $79.98

New From: $45.99 in Stock

Used From: $42.00 in Stock

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