What Is a Humidistat and What Does It Do?

By Anne Fonda

A humidistat is a humidity monitoring device that helps you achieve ideal indoor humidity. Much like thermostats monitor temperature and signal your HVAC system to start heating or cooling, humidistats monitor indoor humidity and signal your whole-house humidifier or dehumidifier to start running to regulate home humidity levels. 

Regulating the humidity in your home can increase your comfort level, your indoor air quality (IAQ), and help prevent problems such as mold growth or static electricity.

A humidistat, also known as a humidistat control or hygrostat, monitors indoor humidity levels and compares the level to your set preferences. If the humidity is higher or lower than your preferences, the humidistat sends a signal to the appropriate HVAC component to adjust the humidity. Once the set humidity is achieved, the humidistat signals the same component to shut off.

Don’t confuse a humidistat with a hygrometer. They are not the same. A hygrometer is a stand-alone humidity monitoring device. It can tell you what your indoor humidity levels are during the day, but it can’t raise or lower the humidity.

The Environmental Protection Agency (EPA) says an ideal humidity for your home is between 30-50%. This is both a healthy and comfortable range. 

High indoor humidity is more than 60% relative humidity. With anything over 60%, your chances of mold and mildew growth skyrocket. That means a decrease in air quality and potential damage to your home. If you regularly have high humidity levels in your home, you need to get to the root of the problem. If you live in a high-humidity climate, a whole-house dehumidifier can increase your comfort.

The recommended indoor humidity for winter is generally between 30-45%. This can help prevent dry skin, respiratory illness, and drying and cracking of wood floors and furniture. As the outdoor humidity drops in frigid temperatures, your indoor humidity may need to drop as well to avoid condensation. 

In summer, the best indoor humidity level is between 40-50%. Your air conditioner or heat pump will naturally dehumidify your home. But if you live in an especially humid climate or have a single-stage system, the cooling unit may have a hard time providing even humidity control. In this case, you might want to consider adding a whole-house dehumidifier or upgrading your air conditioning system. 

Achieving humidity control can make your home feel much more comfortable any time of year. Contact your local American Standard dealer for an assessment and product recommendations tailored to your home and your needs.

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need. 

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Jennie Bergman, Senior Product Manager, Indoor Air Quality