Are All Nest Thermostat Models Interchangeable? A Quick Guide

Google’s Nest Thermostat has been around since 2011, so there have been plenty of different models over the years.

If you have an old Nest Thermostat that you want to upgrade, you probably have plenty of unanswered questions. For example, are all Nest Thermostat models interchangeable?

Nest Thermostat models aren’t interchangeable, despite the similar design. Nest Thermostat models have different wiring configurations, bases, and displays. A newer Nest Thermostat can’t fit onto a different Nest Thermostat model base, but the thermostat base is replaceable.

This article will explain whether Nest Thermostat bases are interchangeable, if you can upgrade your Nest Thermostat, what to do if you don’t have a C-wire, and how to upgrade your Nest Thermostat.

Are Nest Thermostat Bases Interchangeable?

Nest Thermostat bases aren’t interchangeable. All Nest Thermostat models use a different base. Nest Thermostat base plates vary in the number and type of wire connectors, screw hole locations, wire hole size and shape, and several other minor differences.

Unfortunately, upgrading your Nest Thermostat isn’t as simple as taking the old faceplate off and putting the new one in.

Even though all Nest Thermostats use the same display connector and are all circular, you can’t fit a new display onto an old base.

Moreover, every Nest Thermostat has slightly different dimensions, so you can’t retrofit a display even if you tried to.

There are numerous differences between the Nest Thermostat bases.

Each model has a distinct design with a bubble level whose color depends on the model.

The first-generation model had only 8 wire connectors. The Nest Thermostat E had 4, and now it has 6.

Newer models have 10 connectors for stage heating and cooling, humidistats, and hybrid systems.

Can You Upgrade a Nest Thermostat?

You can usually upgrade a Nest Thermostat.

Although Nest Thermostat bases aren’t interchangeable, you can replace the old base with a new one.

However, your new Nest Thermostat won’t work if your HVAC system doesn’t have all the essential wires.

In most cases, you can remove the old Nest Thermostat and replace it with a new one fairly easily. 

It’s as easy as removing a few wires, unscrewing the old base, screwing in the new one, and connecting the HVAC wires to the new base.

Most HVAC systems are compatible with most Nest Thermostat models.

You probably have a Y wire for cooling, an R (or Rc/Rh) for AC power, a G for the fan, etc.

There are only a few differences between Nest Thermostat models.

For example, maybe your old model had an R terminal, and now the new one has both an Rc and an Rh.

All Nest Thermostat models share one requirement, though: a common wire (C-wire) to get stable, consistent power.

If your old Nest Thermostat didn’t have a C-wire connected, it was probably “borrowing” power whenever you turned on heating or cooling. 

Chances are, a newer Nest Thermostat wouldn’t work with your current setup.

But if you do have a C-wire along with a few others for cooling and heating, you can rest assured that you can upgrade your Nest Thermostat. 

Please don’t try to fit the new model onto the old base, though.

What To Do if You Don’t Have a C-Wire

If your new Nest Thermostat doesn’t work because it needs a C-wire, which the old one didn’t use, don’t fret; there’s an easy workaround.

You can use a Hotop C-Wire Adapter (conveniently available on Amazon) for your Nest Thermostat to give it all the power it needs.

This model is compatible with all smart thermostats, and it plugs into a standard wall outlet.

Also, just because your old Nest Thermostat worked without one, it doesn’t mean that the new one will.

Newer Nest Thermostats need more juice because of the improved display and feature set.

Another alternative is to use the fan wire in place of the C-wire.

This involves rewiring your HVAC system control board, though.

You can learn how to do it from the YouTube video below:

How To Upgrade Your Nest Thermostat

If you’re looking to upgrade your old Nest Thermostat, you’re at the right place.

Although you can’t reuse the old Nest Thermostat base for the new model, it’ll still come in handy.

So, here are all the steps that you need to take when swapping out an old Nest Thermostat for a new one:

1. Turn off the power to your HVAC on your home’s main electrical panel.
2. Remove the old Nest Thermostat’s display.
3. Take a photo of the current wiring setup with your phone.
4. Remove all wires from the old base. If they don’t come out easily, use pliers or scissors to snip the wire. Strip the wire afterward to expose the metal ends.
5. Unscrew the old Nest Thermostat base and remove it.
6. Install the new Nest Thermostat base. Ensure that all wires go through the wire hole. Screw in the two screws that came with your new Nest. Depending on the layout, you may need to drill new holes in your drywall.
7. Install all wires following the same layout from the old Nest Thermostat. That’s why you took the photo earlier.
8. If your HVAC doesn’t have a C-wire, install a C-wire adapter. Even though your old Nest Thermostat worked without a C-wire, the new one needs more power to operate.
9. Line up the new Nest Thermostat display with the base and plug it in.
10. Turn on the power to your HVAC system.

Congratulations! You should see the new Nest Thermostat turn on if you did everything correctly.

If the new Thermostat doesn’t turn on, check the C-wire. Or charge the battery in your Nest manually using a USB cable.

Final Thoughts

All Nest Thermostats use a different base with different dimensions and wire terminals, so they’re not interchangeable.

Nevertheless, upgrading to a new Nest Thermostat is fairly simple.

You’ll have to replace the base of your Nest Thermostat.

If the old model didn’t use a C-wire, you could install a power adapter instead.