The Nest thermostat is one of the best-selling smart thermostats on the market today. And for good reason. It learns your temperature preferences and develops an energy-efficient schedule to match. And using geofencing with your phone, the Nest Learning Thermostat and Nest E realize when you’re at your residence or out and about and can adjust temps to help you save even more.

The Nest is compatible with a vast range of 24-volt heating and cooling systems, but it’s always a smart idea to check the Nest thermostat compatibility checker before purchasing one. Don’t forget to contact your energy supplier for valuable rebates, since you may be able to get a Nest for free or close to it.

Once you’ve confirmed it’s compatible, you can either wire it without help or contact a HVAC professional like All Solutions Heating & Cooling. If you’re wiring it without help, you’ll spot a terminal for the C-wire, or common wire. This wire is solely used for powering your thermostat. If your residence or HVAC system is older, you might not have one of these wires. In the majority of cases, Nest says this isn’t a setback as the thermostat can get ample power from other heating and cooling wires.

Sometimes, your heating and cooling system might need that C-wire. And here’s why.

Why Your Nest Keeps Losing Power and Other Malfunctions

The Google Nest Thermostat is an improvement from outdated programmable thermostats that use a combination of wiring and AA batteries for power. It uses a rechargeable lithium-ion battery and wiring to link to Wi-Fi, power its digital display and run your heating and cooling system.

8 Common Nest Thermostat Problems

If it can’t draw ample electricity, Nest says you could run into some of these problems: