How To Reconnect a Nest Thermostat After a Power Outage – A Comprehensive Guide

Did you recently have a power outage in your area, and now your Nest Thermostat won’t reconnect? Don’t worry; there are several reasons why your Thermostat won’t connect, but all of them are relatively simple to fix.

Here are a few methods to reconnect your Nest Thermostat after a power outage:

1. Check the current Nest system status.
2. Check the battery voltage on your Nest Thermostat.
3. Restart the Nest Thermostat.
4. Restart your WiFi router.
5. Perform a complete reset.
6. Check the Nest Thermostat wiring.

As long as your Nest Thermostat is giving out any signs of life, don’t worry. It’ll be a part of your smart home again soon. Read on to learn how to reconnect your Nest Thermostat and do some troubleshooting as you go!

1. Check the Current Nest System Status

Before you do anything, you should check if Nest services are online in the first place. Do this by clicking on this link or going to status.nest.com.

If the Setup & Pairing or some related service is down, there’s no way for you to reconnect your Nest Thermostat.

Of course, your local power outage didn’t cause Nest services to go down. It’s most likely a coincidence.

Or it could be an extremely rare case of a national power blackout.

2. Check the Battery Voltage on Your Nest Thermostat

Did you know that your Nest Thermostat has a built-in battery? That’s right. It’s smart in more ways than one.

The reason behind this is that your Nest Thermostat depends on the power it gets from your HVAC system through the C wire.

The battery allows it to stay powered on and connected, even when you haven’t used your HVAC system for days.

Here’s how you check your Nest’s battery voltage:

1. Open Settings.
2. Tap on Technical Info.
3. Tap on Power.
4. Check the value under Battery voltage.

The voltage must be at least 3.6 V.

If the value is 3.5 V or lower, you can remove the Nest Thermostat from the wall and charge it using a Micro-USB cable.

An alternative would be to turn your HVAC on manually and allow the C wire to charge it. The voltage should go up in a couple of minutes. 

If it doesn’t, you’ll have to check the C wire, but more on that later.

3. Restart the Nest Thermostat

The good old “turn it off and back on again” seems to work for all electronics universally.

So, if the Nest services are up and the battery voltage is fine, this is the quickest solution.

You can restart the Nest Thermostat by doing the following:

1. Open Settings.
2. Go to Reset.
3. Select Restart.
4. Confirm by pressing OK.

Wait a minute for the Nest to restart and try to connect it now.

Restarting the device should’ve fixed any previously bugged services. It also should’ve re-established the connection to your home WiFi.

4. Restart Your WiFi Router

Speaking of WiFi, your router has suffered from a power outage too.

While on the subject, a power outage a few years ago killed my WiFi router. The computer was fine, though.

Hopefully, your router is still in good order. If you’re reading this on your phone via WiFi, it’s probably fine.

Nonetheless, that doesn’t mean that your Nest Thermostat is getting complete access to the Internet.

So, restart your WiFi router by unplugging the power cord, waiting a minute, and plugging it back in. 

Now, wait for a few more minutes. Your Nest Thermostat will connect to your WiFi automatically. If it didn’t, continue to the next step.

5. Perform a Complete Reset

The main difference between a restart and a reset is that a reset will delete all of your settings.

It’ll restore the Nest Thermostat back to factory settings.

That’s why I had you do a restart first.

Without any further ado, here’s how you reset a Nest Thermostat:

1. Open Settings.
2. Go to Reset.
3. Select All Settings.

This will delete your schedules and everything else the Nest Thermostat knows about you.

An alternative to this would be to select Network or Schedule instead.

It’ll keep some of your personal information, but it may not fix your issue.

6. Check the Nest Thermostat Wiring

You probably spent hours trying to figure the Nest Thermostat wiring out. 

Or maybe you had it installed by a professional. Wiring is very confusing, so I don’t blame you.

The power outage may have taken out one of your wires that go into the Nest.

If the wiring is bad, you can’t reconnect it to your smart home.

Before checking the wiring, ensure that the power outage didn’t cause a circuit breaker to trip. 

If it did, switch it on. If it’s not working, you’ll have to replace the broken fuse.

But we won’t go into too much detail about that now.

To check if your Nest Thermostat has power going to it, you’ll need a tester.

It’s best to use the Neoteck Non-Contact Voltage Tester which is conveniently on Amazon.

You don’t have to touch the wire at any point, so you’ll be completely safe.

And since you’ll be working with a hot wire that could shock you, this tool is essential.

If you don’t have a non-contact tester, leave this to a professional electrician.

Unless you have the necessary know-how, of course.

So, here’s how to check the wiring on your Nest Thermostat:

1. Turn off your Nest Thermostat.
2. Pull the Nest Thermostat off the wall.
3. Check the Rc/Rh wires.
4. Check the C wire.

The LED on your voltage tester will turn on if there’s power.

It may also beep. This is an indicator that energy is flowing through the wires.

The Rc and the Rh wires are the power wires.

You may not have both connected simultaneously, and this is normal. 

The C wire is a supplemental power wire.

It may be missing too. A trick is to use the G wire from the fan as a C wire.

But only do this after you cut the main power in the breaker box.

If your hot wires aren’t as hot as they used to be, contact an electrician. If everything seems fine, try reconnecting your Nest Thermostat.

Final Thoughts

Power outages are notorious for making tech gadgets act up.

Unfortunately, wired devices like your Nest Thermostat are sensitive to power fluctuations.

Thanks to this guide, you’ll know how to reconnect your Nest Thermostat to your network.