Why Does Nest Thermostat Say “In 2 Hours?”

After you had changed the temperature parameters on your Nest thermostat, you received a message on the thermostat screen saying “In 2 Hours.” Now you wonder why the thermostat is displaying this message, and if it is indicating some issue, how it can be rectified.

The ‘in 2 hours’ message on the Nest thermostat means that the temperature change you’ve requested will take about 2 hours to become effective.

Image of Nest thermostat saying 'in 2 hours'
Image of Nest thermostat saying ‘in 2 hours’

Usually, it takes less than 10 minutes, but there are at least 4 possible reasons for the 2-hour delay. Fortunately, 3 of the 4 reasons don’t need any rectifying steps, and you might be able to fix the 4th issue yourself. 

In this article, I’ll discuss the three reasons commonly causing a Nest thermostat to display this message but don’t need any rectifying and will then provide you with information, tips and procedures to rectify the one issue that might need attention. 

The primary reasons why your thermostat says “In 2 Hours”

It is normal for your Nest thermostat to display a message indicating how long it will take for a setting change to become active. The thermostat will estimate this time in increments of five minutes. Usually, it takes less than 10 minutes to reach a new temperature. Therefore if it indicates “In 2 Hours” it is actually informing you that something “abnormal” is causing a possible delay. 

The reason for the delay can be any of the following;

  1. The thermostat is in its learning phase (no rectifying necessary),
  2. there was a recent system reboot (no rectifying necessary),
  3. a software update of the firmware on your thermostat has been performed (no rectifying necessary), or 
  4. the C-wire is disconnected, or not properly and securely connected and needs attention. 

Let’s look at each reason in more detail.   

Reason 1. The thermostat is in its learning phase

Nest thermostats are designed to create personalized schedules to keep the temperature in your home comfortable. Within about a week after installation, your Nest Thermostat will have automatically learned your routine, heating habits, and preferences. It will then create a personalized heating schedule for your home. As your preferences change, it continuously learns and adapts.

Over time and with repetition, the electronics in your thermostat will “remember” how long it takes to go from one setting to another. If your thermostat has recently been installed, it might still be in the learning process. It is still learning about what has to change in your home when temperature settings are being changed and in which areas of the home changes will take place. 

When the thermostat’s electronics are not yet ready to make the calculations of how long it would take for the new settings and schedules to be applied, it automatically gives you an estimate of two hours. It will later be in a position to give you more accurate estimates.

Thus, if you’ve installed a new Nest thermostat recently, you don’t have to worry about the message. Usually, the temperature changes will be completed in less than 2 hours. The more “experienced” your thermostat becomes, the more accurate estimates you’ll receive in the future. You just have to be patient – there is no issue to be resolved. 

Reason 2. There was a recent system reboot

Remember, when your HVAC system or the thermostat has been rebooted for any reason, your Nest thermostat’s memory might be erased. It then has to go through the whole learning procedure again as if it has been newly installed. And just like a recently installed new thermostat, your rebooted thermostat might not yet be ready to make the calculations of how long it would take for the new settings and schedules to be applied. Therefore, it will automatically give you an estimate of two hours.

In other words, there is nothing to fix, and you just have to be patient. In the future, you’ll get better estimates as the rebooted thermostat is learning your routines and preferences. 

Reason 3. A software update of the firmware on your thermostat has been performed

It is quite common that after a software update of the firmware on your Nest thermostat, the “In 2 Hours” message is displayed on the thermostat screen. Just as with the previous two reasons which I’ve discussed above, there is no rectifying action needed. When the thermostat has completed the learning curve, it will regain its “memory” and provide you with better estimates.   

Reason 4. The C-wire is disconnected or not properly and securely connected

When you get all of a sudden the “In 2 Hours” message on the Nest thermostat screen without you changing the settings, it might most probably be a C-wire problem. And this is an issue that usually needs rectifying actions. 

The common wire (C- wire) connects your Nest thermostat with your HVAC control panel. The purpose of the C-wire is to provide a 24-volt power supply to your Nest thermostat, whether the HVAC system is on or off.  When the C-wire is not connected, your Nest thermostat might become underpowered, and ultimately this can lead to poor internet connectivity. Without a good internet connection, your thermostat cannot control the temperature in your home, and an “in 2 Hours” message might be displayed on the screen.  

Fortunately, you can quickly determine whether a C wire is connected or not. All you have to do is to scroll to “Settings” on your Nest and click on “Equipment.” If all the wire connections are in place, you will see the following letters displayed in a tab on the screen:

  • G (fan)
  • W1 (heat)
  • RH (power)
  • C (common wire) 

If no “C” is in the tab, it means there is no C-wire connected

There are several ways to install/connect a C-wire, and I’ll briefly discuss some of them. If you are an experienced DIYer, especially with electrical installations, you should be able to fix the problem yourself. If you don’t feel comfortable working with electrical wiring, it is recommended that you contact an HVAC technician. 

One possible solution – Get a C-wire adapter

I’ll recommend the installation of a C-wire adapter because it is, from a technical point of view, the easiest solution. Apart from the adapter, which you can purchase at your nearest Nest retailer, you only need a power outlet close to your Nest thermostat to plug the adapter in. 

Put off all power to your thermostat and HVAC system at the circuit breakers, and remove the thermostat from the wall.  Remove the RH wire on your Nest thermostat and replace it with one wire from the adapter. Then plug the other wire of the adapter into the thermostat’s C-terminal. 

Put the thermostat back against the wall, plug the adapter into the power outlet and put on the circuit breakers again. Your thermostat will now always receive 24-volt power and when it is powered enough again, the “In 2 Hours” message will disappear.

Installation of a C-wire adapter

Another possible solution – Use the G-wire 

If there is no C-wire and you don’t want to install an adapter, you can use the G-wire. The G- wire is green and allows you to control the blower fan manually. Move the green wire to the C- wire terminal on your thermostat, and you will have a C-wire installed. 

More expensive solution – Get a new C-wire installed 

If no C-wire is available, you don’t want to purchase a C-wire adapter and don’t want to disable the manual option to control the blower fan by using the G-wire, you can get an HVAC technician to install a new C-wire between the HVAC control panel and the Nest thermostat. This is not a DIY job and might be expensive, but is an option to keep in mind.

How to install a new C-wire


Q1: Does the C wire have power?

A1: A C-wire, or a common wire, runs from your low voltage heating system (24v) and carries continuous power to your thermostat. 

Q2: What can I use instead of C-wire?

A2: If there is no C-wire, you can use a G-wire instead. However, then you’ll only be able to use your fan independently when the heating or cooling is running.


The bottom line is that when you receive the “In 2 Hours” message on your Nest thermostat screen, you usually don’t have to worry because the message is, in most instances, displayed as a result of the thermostat’s learning procedure that is still in process. If it is because of a disconnected C-wire, the problem can easily be fixed by installing a C-wire adapter. 

Charles John

Experienced HVAC technician with 8 years of experience in the industry. Capable of handling all sorts of heating and cooling equipment as well as proficient in operational management, construction-related techniques such as preventative maintenance, electrical troubleshooting and AutoCAD

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