How Does a Humidistat Work?

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Water is the essence of life but moisture can wreak havoc on a home or business. A humidistat helps regulate humidity levels to prevent corrosion, minimize health risks, and more. In this article, we’ll explain what it is and how a humidistat works.

What is a Humidistat?

A humidity control system that works with the home’s cooling and heating device, and maintains a specific level of humidity across the house by adjusting the moisture level automatically is called a humidistat. The humidistat sends signals to the humidifier to stop the water supply or turns on/off the air conditioner once the set humidity level is attained. It not only helps in maintaining a comfort level in the house but also prevents outbreaks of mildew and mold in humid regions.

Risks of high indoor humidity include the growth of viruses, fungi, bacteria, mildew, and dust mite infections. Other issues like rotting of window trims due to collected condensation on windows, peeling of paint and wallpaper, damaging furniture, etc., are also possible due to excessive humidity levels. Excessive humidity is also a big concern for recreational vehicles, which is why dry kits for storing boats, RVs, and automobiles are recommended since humidistats are not an option.

A humidistat is also referred to as a hygrostat.  Since it similarly regulates humidity, it is analogous to a thermostat, which measures temperature. Humidistat is not just used as a humidity control system in homes but is also a part of microwave ovens, refrigerators, climate-controlled warehouses or greenhouses. It is also used on a commercial level, particularly in the medical and food industries.

How Does a Humidistat Work?

In a humidity control system, which caters to the whole house, the central HVAC system is connected to the humidifier/de-humidifier. The airflow is regulated and the humidity is controlled throughout the place as the humidistat adjusts the dampers, valves, or other switches. The humidistat can also be wired to the thermostat to run with the AC and control the humidity in the house independently of the temperature. When the temperature is high and the humidity level is low, the humidistat will not turn on the AC, but will do so when the humidity level spikes to higher levels. This helps with the optimal usage of the HVAC system and will also help with cost-savings.

One of the most important parts of a humidistat is a sensing element that is made of alternate metal conductors fitted on a flat plate. A relay amplifier attached to this sensing element gives accurate humidity levels by reading the signals sent by the sensing element. The relay amplifier does this is by measuring the electrical resistance that varies with changing humidity levels, caused between the metal conductors. Based on these readings, if the air is too dry, the humidistat turns on the humidifier and vice versa. This ensures that the room is not over-humidified or de-humified.

Benefits of a Humidity Control System

  • Works with both heating and cooling systems
  • Easy to maintain – no refilling using multiple buckets of water
  • No need to constantly adjust the thermostat, as the humidistat does that for you
  • Saves electricity costs
  • Prevents the house from the ill-effects of higher humidity
  • Extremely dry air can be linked to respiratory problems, dry skin, chapped lips, increased response to allergens, sore throats, etc., which can be prevented by regulating the airflow


With a wide range of benefits, a humidistat is a great system that improves the quality of living by safeguarding your home from humidity related issues.  By regulating the humidity, a humidistat can alleviate and prevent mold, mildew, corrosion, and more. It is also used at a commercial and industrial level, including professional offices, healthcare facilities, food production and storage, manufacturing, and much more.

Learn more about moisture damage solutions.