Sensi smart thermostat: what its symbols and messages mean

Sensi (from Copeland, formerly Emerson) thermostats show connection trouble in the top-left corner: an X, or no Wi-Fi icon at all. On most systems Sensi needs a C wire to keep Wi-Fi on, and it turns the Wi-Fi off to save the batteries when it cannot get power from the system, so a missing Wi-Fi icon is often a power question, not a router one.

Wi-Fi and X icons are top left, the battery indicator top right, and a padlock by the room temperature. Sensi describes the Sensi Smart, Sensi Lite and Sensi Touch and Touch 2 separately where they differ.

1. No Wi-Fi icon in the top-left corner

   The thermostat’s Wi-Fi radio is off. Sensi gives two main causes: low batteries (the radio turns off to save power), or a system compatibility or C-wire issue.

   Sensi smart thermostat and Sensi Lite. 3 steps from Sensi on its page. About wiring or power: only Sensi’s own instruction is repeated.

2. An X icon, or “Not connected to network”

   The thermostat can’t connect to your home Wi-Fi network.

   Sensi thermostats. 4 steps from Sensi on its page.

3. Flashing X next to the Wi-Fi icon (Sensi Lite)

   Sensi says the problem is likely system compatibility or the C wire: when the thermostat finds it is outside its compatibility requirements it may turn the Wi-Fi off for a while to save battery, so it goes offline often.

   Sensi Lite. 1 step from Sensi on its page. About wiring or power: only Sensi’s own instruction is repeated.

4. “Set To” temperature flashing

   A/C Protection is on: there is a 5-minute delay before the thermostat turns on the air conditioner or heat pump after a call for cooling, to prevent damage when cooling is turned off and on quickly.

   Sensi Smart and Touch 2 (on the Lite the “On” icon is delayed; on the Touch the face plate turns blue). 2 steps from Sensi on its page.

5. Padlock icon

   Keypad Lockout is on: the thermostat’s buttons are disabled so the set points and settings can’t be changed on the wall; the Sensi app still controls it.

   Sensi Smart (by the room temperature), Lite (when you press Menu), Touch and Touch 2. 1 step from Sensi on its page.

6. Solid white or partial display

   Sensi ties a solid white or partial display to the “C” wire connection: the thermostat needs 20 to 30 VAC from the system.

   Sensi Touch and Touch 2 (solid white); all Sensi models (partial display). 3 steps from Sensi on its page. About wiring or power: only Sensi’s own instruction is repeated.

7. Smart Alert: Loss of Cooling

   An app alert that the home is not cooling. Sensi says the thermostat does not know whether the cooling system is actually on: if the set temperature is below the room temperature it tries to turn cooling on, but a system problem can stop it running.

   Sensi thermostats with Smart Alerts in the app. 3 steps from Sensi on its page.

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