Sensi Lite Thermostat Operation Manual

The Sensi Lite Smart Thermostat (models: 1F76U-22WFB series, ST25 series) is a Wi-Fi enabled programmable thermostat for 24V HVAC systems. It offers smart control via the Sensi app, including scheduling, remote access, and energy savings. Compatible with single/multi-stage conventional systems, heat pumps, and more. No common wire required with most systems. Below are the key specifications and operation instructions.

1. Key Specifications 2. Operation Instructions 2.1. Initial Setup 2.2. Setting the Clock and Day 2.3. Operating in Non-Programmable Mode 2.4. Operating in Programmable Mode 2.5. Advanced Features 2.6. Troubleshooting 3. Installation Instructions 3.1. Remove Old Thermostat 3.2. Installing New Thermostat 3.3. Battery Location 3.4. Wiring and Configuration

Key Specifications

Type: Wi-Fi enabled programmable smart thermostat for 24V HVAC systems
Compatibility:
- Universal: 2 Heat/1 Cool or 1 Heat/2 Cool; Single/Multi-Stage Heat/Cool; Heat Pump (2 Heat/1 Cool); Gas/Oil/Electric; 3 Wire Zone Valve; Millivolt; Economizer; Humidity Control; Dual Fuel
- No C-wire required with most systems; required for heat-only, cool-only, heat pump
- Works with Sensi app on iOS/Android; compatible with Alexa, Google Assistant, Samsung SmartThings
Power Source:
- Hardwire: 20-30 VAC, 50/60 Hz
- Battery Power: N/A
- Power Sharing (PS) or Hardwire/Common (H)
Electrical Rating:
- Terminal Load: 1.5A per terminal, 2.5A max (all terminals)
- Terminals: R, C, W/E, G, Y, O/B, Y2, W2, L, AUX
Temperature Range: Set-point: 45°F to 99°F (7°C to 37°C); Operating Humidity: 0%-90% RH non-condensing; Storage: -20°F to 150°F (-29°C to 65°C)
Operating Conditions:
- Indoor use; Wi-Fi: 2.4GHz network required
Dimensions: 5.6" L x 3.25" H x 0.77" D; wall-mount design
Features:
- 7-day programming (up to 8 periods/day) via app
- Geofencing, energy reports, remote control, filter reminders
- ENERGY STAR certified; saves ~23% energy
- Intuitive controls, 2.3" LCD backlit display
Thermostat Configuration Options:
- Models: 1F76U-22WFB series, ST25 series
- UL listed; professional or DIY installation

Operation Instructions

Initial Setup

1. Download Sensi App: Install from App Store or Google Play; create account with email.
2. Power On: Install on wall after wiring (see Section 3).
3. Configure System:

Select model (ST25/1F76U-22WFB), system type in app.
Connect to 2.4GHz Wi-Fi via app (use Sensi Security Code).
App guides through scheduling, location setup; time syncs automatically.

Setting the Clock and Day

1. Syncs automatically via Wi-Fi.
2. Manual (Wi-Fi off): Use app or thermostat menu to adjust time/date.
3. Day auto-detected from schedule/location.
4. Time zone set in app.

Operating in Non-Programmable Mode

1. Select Mode: Press Mode to cycle Heat, Cool, Off, Aux, Auto.
2. Adjust Temperature: Use up/down arrows.
3. Fan Control: Press Fan for Auto/On.
4. Manual Override: Turn Schedule Off for permanent hold.

Operating in Programmable Mode

1. Factory Schedule: Default 7-day via app (up to 8 periods/day).
2. Custom Schedule:

Use app: Schedule tab for times/temps.
Manual: Menu > Schedule; set periods.
Enable geofencing for auto-adjust.

3. Temporary Override: Arrows for hold until next period.
4. Permanent Hold: Schedule Off.
5. Disable: Schedule Off in app/unit.

Advanced Features

1. Remote Control: Via Sensi app with Wi-Fi.
2. Energy Saving: Usage reports, geofencing, alerts, filter reminders.
3. Voice Control: Compatible with Alexa, Google Assistant, SmartThings.
4. HVAC Monitoring: System alerts via app.
5. Circulating Fan: Programmable fan option via menu.
6. Humidity Control: If accessory installed.
7. Keypad Lock: Partial/total lockout via menu.

Troubleshooting

No Display: Check power; ensure 20-30VAC.
No Heat/Cool: Verify mode/wiring; check HVAC/breaker; reconfigure in app/menu.
Wi-Fi Issues: Ensure 2.4GHz; restart app/router; check permissions.
Invalid Config: Check compatibility; reset via app.
Factory Reset: Menu > About > Reset.

Installation Instructions

Warning: Turn off power at breaker before starting. DIY or professional installation.

Remove Old Thermostat

Switch off power to HVAC at breaker/fuse.
Remove old cover (screwdriver or latch).
Photograph wiring for reference.
Label wires with stickers, disconnect one at a time.
Remove base; secure wires to prevent falling.

Installing New Thermostat

Mount Base: Level, mark holes, drill/anchor, screw base.
Connect labeled wires to terminals.
Push excess wire into wall.
Attach display to base.
Restore power; follow app for setup.
Initiate Wi-Fi: Menu > Mode; icon flashes.
App: Add device, select model, identify wires, connect Wi-Fi, name/register location.

Battery Location

No batteries; powered by hardwire (20-30 VAC).

Wiring and Configuration

Match labels to terminals. C-wire required for heat-only/cool-only/heat pump. Configure via app or Menu > Advanced Setup.

System Type	Key Connections
Conventional Single Stage	R to R, C to C, G to G, Y to Y, W/E to W/E
Heat Pump Single Stage	R to R, C to C, G to G, Y to Y, O/B to O/B
Two-Stage Conventional	R to R, C to C, G to G, Y to Y, Y2 to Y2, W/E to W/E, W2 to W2
Dual Fuel Heat Pump	R to R, C to C, Y to Y, O/B to O/B, W/E to W/E
Humidifier/Dehumidifier	Y2/W2 or AUX

Caution: Secure connections. Check compatibility.

Terminal Definitions:

R: Power (24V)
C: Common
W/E: Heat/Aux
G: Fan
Y: Compressor
O/B: Reversing Valve
Y2: 2nd Stage Compressor
W2: 2nd Stage Heat
L: System Monitor
AUX: Accessory

Menu Configurations: Auto Changeover, Programmable Fan, Filter Reminder, Keypad Lock, Temp Limits, etc.