What Is a Humidistat?

Does your home often feel clammy and damp? Or maybe your house leans toward the dry side, leaving your skin feeling itchy and dehydrated.

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Humidity levels often change with the seasons, which can leave you constantly trying to balance the moisture in the air. A humidistat is a simple tool that can help you maintain a comfortable humidity level in your home.

What Is a Humidistat Control?

So, what is a humidistat control, and why would you want one? It's an electronic device, similar to a thermostat, used to measure and manage humidity levels. It connects to your humidifier or dehumidifier and tells it when to run, similar to the way your thermostat tells your HVAC system when to turn on and off. Portable humidifiers and dehumidifiers usually have humidistats built into them. If you have a whole-house humidifier or dehumidifier connected to your HVAC system, it has a humidistat as well. In some cases, it might also trigger other appliances, such as an evaporative cooler or fan.

What Does a Humidistat Look Like?

Humidistats have sensing elements (which are flat plates often made of a metal film or synthetic polymer) fitted with conductors. It also has a relay amplifier that reads the signals. The system might also include a controller that looks similar to a thermostat. It might use buttons, knobs or touchscreen controls to set the desired humidity level.

How Does a Humidistat Work?

The sensing element on the humidistat measures the relative humidity levels in the home by absorbing the moisture in the air. As the sensing element expands or contracts based on the moisture level, it creates electrical resistance with the conductors. The sensing element then sends signals about the resistance to the relay amplifier, which measures that data and decides if the humidifier or dehumidifier needs to run.

This is where a thermostat and a humidistat are similar. Just like you set a temperature on your thermostat, you set a desired humidity level on your humidistat. If the relative humidity that's measured by the humidistat is outside the range you choose, the device signals other appliances to turn on. For example, if the humidity level gets too high, it might turn on your dehumidifier or fan. If the humidity drops too low, it turns those appliances off or turns on your humidifier.

The actions that happen depend on what components you have connected. For example, if you wire the thermostat and humidistat together, it controls your AC to keep humidity levels in the ideal range.

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What Should My Humidistat Be Set At?

You generally want your indoor humidity to fall between 30% and 50%, with a level somewhere near the middle that offers a good balance. However, your ideal humidity level might be different from someone else's. If your humidistat setting makes the air feel too dry, increase it to a higher range. Likewise, if the air feels too moist or you notice condensation around your home, try lowering the humidistat setting.

Several factors affect the humidity levels in your home. For example, the climate you live in can affect the humidity indoors. You might need to adjust your settings based on seasonal changes. For example, you might raise the humidity level in the winter when the air is usually drier.

Do I Really Need a Humidistat?

While a humidistat isn't required, it can be a helpful device for keeping your home comfortable and preventing damage. Low humidity levels dry out your skin and nasal passages and can cause wood to crack. Excessive moisture causes condensation and could lead to mold and mildew growth.

Having a humidistat helps optimize your HVAC system and makes any extra components, such as a whole-house humidifier and dehumidifier, work more effectively. Once you set the levels, the humidistat takes care of everything else, so you're not constantly adjusting individual components. Controlling the humidity in your home can also ease the strain on your heating and cooling system, which could lower your utility bills.