Nest thermostats have made controlling the weather in your home.
They make controlling heating, cooling, and humidity levels a breeze.
Many people connect them to their existing systems, but are they compatible with humidistats?
A Nest thermostat won’t work with a humidistat. The design of standard digital humidistats makes connecting both devices impractical. It’s best to use your Nest thermostat as a humidistat if the humidifier is compatible with the Nest protocol.
If you’re thinking of hooking up your Nest thermostat to your humidistat, this article will help clear all questions you might have.
How Nest Thermostats and Humidistats Work
To understand why you can’t connect your humidistat to a Nest thermostat, you need to first look at how they both work.
A humidistat is designed to measure the amount of moisture present in the air in any room.
The device features a sensing element and a relay amplifier which work together to deliver accurate humidity levels.
The setup works by triggering electrical resistance in the conductors installed on the sensing element depending on the amount of humidity in the room.
The relay amplifier measures the amount of resistance, which informs the system if the air is too dry or at an optimum level—in which case it’ll either turn on the humidifier or turn it off.
All portable humidifier or dehumidifier systems are equipped with a humidistat.
On the other hand, a Nest thermostat is an all-around temperature control device.
When connected, you can use it to manage all the components of your HVAC system.
It comes with several connection ports, and the interface provides you with multiple options for heating or cooling your home.
You can control the thermostat on your smartphone or tablet—even when you’re away from home.
As time passes, the system learns from your heating and cooling needs, adjusting automatically to give you the optimal home temperature.
The smart element helps users save money on energy bills.
You’ll get pop-ups on the display when the device is saving you money.
Why You Can’t Connect a Humidistat to a Nest Thermostat
As we’ve seen above, a humidistat is the control device for a humidifier, while a Nest thermostat is a control device for the wider HVAC system.
Connecting both devices is impractical because they are designed to do the same thing—controlling the humidifier or dehumidifier.
Secondly, the internal mechanism of both devices won’t allow such a connection.
A humidistat needs an R and C wire connection to control the humidifier, while the Nest thermostat only has provision for a C wire connection.
The disparity in relay requirements makes the connection impractical.
Here’s a YouTube video that goes into more detail on the wiring:
A better way to hook up the humidifier to your Nest thermostat is to run a direct connection.
Connecting Your (De)Humidifier to a Nest Thermostat
A Nest thermostat works effectively with a humidifier.
The product is compatible with most dehumidifier or humidifier systems that aren’t tied directly to the air conditioner and those that only need one low-voltage wire connection to work.
The good thing is that there’s a compatibility checker you can use to confirm your humidifier’s compatibility with a Nest thermostat.
If you already have the thermostat and are considering buying a humidifier, the checker tool will also help you choose compatible options.
Compatible humidifier systems will come with the following labels: HUM2, H2, H, HUM1, and HUM.
For dehumidifiers, the labels on compatible systems will include any of the following: DHUM, DEHUM, DEHUM2, D, DHUM2, DH, D2, and DH2.
After you’ve confirmed compatibility or bought a compatible (de)humidifier, you can proceed to connect it to the Nest thermostat.
All you need to do is to connect the C-wire to their respective positions on both devices.
If you know how to identify the C-wire and configure the humidifier on the Nest thermostat, you can complete the installation process independently.
The compatibility checker provides the details you need to complete the connection.
The guidelines are fairly clear to follow.
However, if you feel overwhelmed by the process or don’t have any experience with such connections, you should consider hiring a professional.
It’s a quick job they can complete in a few minutes barring any other problems.
Hiring a professional also allows you to get a complete analysis of your home’s heating and cooling to unearth any further problems.
It also ensures you won’t accidentally connect the wrong wires and damage your components—or worse, start a fire.
So, only take on the installation process if you’re certain it’s a task you can complete on your own.
Possible Problems With the Nest Thermostat and Dehumidifier Connection
One of the main complaints from people who have connected their thermostat to a (de)humidifier is that the Nest doesn’t auto-adjust the dehumidifier on its own.
The result is often a room that is too dry or too humid—barring any manual intervention.
The concern is legitimate because the Nest thermostat doesn’t have the mechanism of a humidistat, as we discussed above.
It relies on your manual inputs and information gleaned online about the weather in your locale to control your systems.
Therefore, if you’ve just installed the (de)humidifier, the Nest thermostat will need some time to understand when it should trigger the (de)humidification system.
During this period, you’ll need to control the system manually to prevent problems such as moss growth due to excessive moisture content in the air.
After a while, the Nest can near-accurately figure out when to activate or deactivate humidity.
Final Words
Your humidistat won’t work with a Nest thermostat.
They play similar roles in the home, so you have to use one or the other.
The connection options for both systems also differ significantly.
It’s best to connect your (de)humidifier directly to the Nest thermostat instead.
The installation process is straightforward after you’ve confirmed the compatibility of both systems.
However, don’t hesitate to hire a professional if you feel it’s too much work for your DIY experience level.
You don’t want to damage your Nest thermostat or (de)humidifier.
