What If There Is No C-Wire? If you do not have the C-wire, you can try the following steps, but please confirm with your HVAC manufacturer or an electrical engineer first.

1. Furnace Part: Connect the G-wire to the C-terminal, then use a black jumper wire to connect the G and Y terminals (or the W-terminal if you need heat, otherwise connect to Y).
2. Thermostat Part: Connect the G-wire to the C-terminal on the wall plate. The G-terminal on the wall plate should be left blank.

What is a C-Wire? A C-wire, also known as a common wire or a "continuous wire," is an electrical wire that provides a constant source of power to a thermostat or other HVAC (Heating, Ventilation, and Air Conditioning) components.

TJ560 WiFi Smart Thermostat vs. TJ550 WiFi Smart Thermostat TJ560 WiFi Smart Thermostat: - Customer Reviews: 3.3 out of 5 stars (82 reviews) - Price: $98.99 - Screen Size: 4" - Screen Operation: Touchscreen

TJ550 WiFi Smart Thermostat: - Customer Reviews: 3.9 out of 5 stars (119 reviews) - Price: $69.99 - Screen Size: 2.8" - Screen Operation: 3 Touch Buttons

Vine Programmable Thermostat: Smart Control for Your Home's Temperature The Vine Smart Thermostats allow you to take control of your home's temperature with a range of convenient features:

【Wide Compatibility】This AC thermostat is compatible with approximately 90% of HVAC systems, including Conventional (2H/2C), Heat Pump (4H/2C), natural gas, electric, hot water, gas fireplaces (24 Volts), oil heat sources, and heat pump, dual fuel systems. All system types require a common wire (C-Wire).

【Quick Install】Our home thermostat for AC and heating can be installed easily in 20 minutes or less, with step-by-step online guides and instructional videos to assist you.

【Remotely Control & Voice Control】Control and monitor the WiFi thermostat from anywhere using the Vine Thermostat App or Smart Life App. It is also compatible with Alexa and Google Home, allowing for hands-free voice control.

【Live Smart & Energy Saving】With 7-day programmable schedules and Auto Home/Away mode, the thermostat automatically adjusts the room's temperature, keeping your home comfortable when you arrive and helping you save on HVAC expenses (ENERGY STAR certified).

【Multi Practical Functions】Our home programmable thermostats offer a range of features, including temperature alerts, filter change reminders, automatic time/date synchronization, and child lock functionality, ensuring your comfort and peace of mind.

product information: