Intelligent Thermostat T40K


Energy efficient. Charismatically comfortable. Astutely aware.

Saving energy feels good. Especially when your home gets safer and more comfortable in the process.


  • Proactive detection of HVAC system problems
  • Self-configuration for easier installation
  • Flexible, easy-to-use controls
  • Humidity control
  • Works seamlessly with whole home security, automation and energy saving platform

Requires Surety Home, Surety Complete, or Surety Automate.

1 year warranty


Relax, I’ve got your back

– The smart thermostat that protects you

Protects your heating and cooling system

Machine learning proactively monitors the HVAC system, alerting you to trouble conditions before they cascade into complete system failures, requiring expensive emergency repairs or system replacements.

Protects your home

By intelligently balancing both humidity and temperature set points, the thermostat can help prevent health risks and cleanup costs caused by mold while maximizing comfort. Winter Freeze Protection can alert you before pipes freeze and burst.

Protects your wallet

Whole-home intelligence helps save on monthly energy costs by automatically adjusting to real-time activity and occupancy changes, open windows or doors, and your geo-location.

Unreliable internet?

Connects to your alarm panel for reliability and control. This allows both wifi and cellular remote control of the thermostat for maximal reliability with dual path communication. Requires system compatible with dual path communication.

Concerned about security?

Speaks the Z-Wave S2 security protocol and connects through your security system. It was designed from the ground up with security in mind.

Never stops learning

It already packs industry leading features. Thanks to automatic firmware updates it continues to get smarter over time.

Don’t worry, this device integrates seamlessly

Surety is your connection to the award winning ecosystem, allowing you to use hundreds of best-in-class security and home automation devices from a single app that runs on almost anything. All that and the industry’s best customer service are why Surety is your home’s best friend.

Specs & Guides

Part number
24V power, requires C-Wire connection
4.7 x 4.7 x 1.07’’ (12 x 12 x 2.72 cm)
Operating temperature range
41°F to 95°F (5°C to 35°C)
Z-Wave SmartStart, Z-Wave S2 Authenticated/Unauthenticated
Humidifier support
Dehumidifier support
Heating (Fossil or Electric)
Up to three stages
Up to two stages
Heat pump with AUX
Compatible with both O and B systems
Dual fuel (Fossil AUX Heat) support
Ventilation control
HRV, ERV, external air baffle

Plan Compatibility

Security Alarm & Automation
Automate Alarm Home
Cameras Only
View Cam Cam Plus
Alarm, Automation & Cameras
Protect Complete


How do I automatically change the temperature when I leave and come back home?
Configure a “Smart Away” rule under Thermostat Schedules. It can be based on whether the security system is armed away or based on mobile device geofences.

Still have questions? We’ve got answers!
The Surety support forum is the #1 resource for answers to all your questions about setting up and using the thermostat.
Find Answers

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