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YS4003 Smart Thermostat, Heat Pump Compatible

  • $99.59
  • $129.99
Shipping calculated at checkout.

Customer Reviews

Based on 2 reviews
Derek Loadholtz
Works great for app/manual control

I installed it and it linked up to the hub immediately and gives great manual control via the thermostat or the app. I am not currently using the programmable schedule option; however, the thermostat time of day is never correct so I presume that the programmed schedule would not work very well.

There is apparently no battery back-up so any power blink/outage appears to reset the thermostat clock. That’s a weakness if the programming mode is something you’ll want to use and thus far the only reason I would not replace my other thermostats that do use programming mode with this unit.

I’d like to see an option where it could interact with a separate temp/humidity sensor(s) already on the hub for customizing control for hot/cool spots in rooms other than where the thermostat is located.

Adam Allard
Thermostat works great

This unit performs very well. You will need a 24 VAC power supply for it to operate.


  • Smart replacement thermostat with app control


  • Remote control with the YoLink app
  • IFTTT integration (limited Alexa and Google Assistant integration)
  • Unique heating/cooling schedule for each day of the week
  • Color LCD display with customizable color schemes
  • User-friendly on-screen settings menu
  • ECO Energy Conservation Operation saves you money on power bills
  • 24 VAC systems only
  • Works with most one-stage heating/cooling systems in the U.S. and Canada
  • Five wire system with “C” Common wire required (for heating & cooling)
  • YoLink Hub required


  • Save money on your power bills by scheduling your heating/cooling temperatures to automatically adjust based on the day of the week and time of day; automatically raise the cooling set temperature to a higher setting while you are at work
  • Use the convenient YoLink app to check and change your thermostat’s temperature and mode, anytime from anywhere
  • Enable the ECO feature to automatically adjust set temperatures for savings on your power bill – ideal for when you are away
  • Voice control with Alexa and Google Assistant integration
  • Create custom automation with IFTTT integration



  • YoLink Hub with an internet connection (wired Ethernet or 2.4GHz Wi-Fi). Refer to the Hub user guide for additional information
  • Smartphone or tablet running iOS 9 or higher, Android 4.4 or higher
  • Existing wiring with at least 5 conductors, including a “C” Common wire
  • Tools Required, Including but Not Limited to: Drill, Phillips/cross screwdriver, small slotted screwdriver, optional mounting anchors
  • Installation Difficulty Level: Medium-to-Difficult (May require installation by an electrician or experienced installer if a “C” common wire is not existing)


  • Semtech® LoRa® RF Module YL09 microcontroller with 32-Bit RISC processor
  • Multi-color LCD Display
  • Control Buttons (6)
  • Power: 24 VAC (From HVAC system or customer-supplied transformer)
  • Color: White
  • Dimensions (L x W x D): 5.12 x 3.58 x 0.55 inches (130 x 91 x 14 mm)
  • Scheduled Temperature Range: 32°F – 90°F (16°C – 32°C)
  • Detection Temperature Range: 14°F – 122°F, ±0.54°F (-10°C – 50°C, ±0.3°C)
  • Detection Humidity Range: 0 – 100%, +/- 3%
  • ECO Setting Range: 2°F – 9°F (1°C – 5°C)
  • Calibration Range: 0°F – ±9°F (0°C – ±5°C)
  • Environmental:
  • Operating Temperature Range: 14°F – 122°F (-10°C – 50°C)
  • Operating Humidity Range: 0 – 95% non-condensing
  • Intended for indoor use only


  • (1) YoLink Thermostat
  • (1) Mounting Base
  • (2) Wall Screws
  • (2) Anchors
  • (1) Quick Start Guide