What Is A Hygrometer & How Does It Work123

Does your home often feel dry? Or too muggy? If you are experiencing chapped/dry skin, or difficulty breathing while in your home, you may need to get your humidity level checked out. Humidity levels that are not between the averages of 30- 50 percent can be potentially dangerous for your health. You can personally check your humidity level in your home by using a hygrometer.

A hygrometer is an appliance that is designed to calculate the amount of humidity in a room or building. While a hygrometer can’t actually prevent mold from growing, it can warn you to take any steps necessary before the problem occurs. Hygrometers can provide the accurate levels of relative humidity and absolute humidity. Relative humidity is the percentage of humid moisture in the air. Absolute humidity is the actual amount of moisture in the atmosphere.

What Makes a Hygrometer Work?

There are two commonly used types of hygrometers: Mechanical hygrometer and wet and dry bulb psychrometer.

Wet and Dry Bulb Psychrometer

This is the easiest way to measure humidity. This type of hygrometer is equipped with two mercury thermometers, where one has a wet bulb and the other has a dry bulb. Because of the evaporation of water on the wet bulb the temperature will drop and read a lower temperature than what is displayed on the dry bulb. The difference between the two temperature readings equal the amount of relative humidity in the atmosphere.

Mechanical Hygrometer

A mechanical hygrometer requires a little more effort to determining humidity levels in a room.

  • This tool was first created in 1783 by a physicist named Horace Benedict de Saussure.
  • Mechanical hygrometers work by using an organic material, typically a piece of hair where its behaviors can predict the amount of humidity in the air.
  • If you’ve ever noticed how human hair tends to frizz when there is a lot of moisture in the air or it is very hot outside, then it will be easy for you to understand how this tool works.

For example, the piece of hair is attached to a spring and needle instrument that exposes the hair to humidity. Based on the reaction of the hair, the humidity level can be classified. Although a wet and dry bulb is more accurate and easy to understand, a mechanical hygrometer is still as effective.

How to Reset Your Hygrometer

Should you need to ever reset your hygrometer, you can do so by using at-home methods:

  • In a room with normal, consistent temperature, place your hygrometer in a cup or container filled with salt water on a counter space. Leave it to sit for 10-12 hours.
  • After the allotted time, the hygrometer should read a standard relative humidity level of 75 percent.
  • This process should be performed at least once a year to ensure your hygrometer is always providing accurate results.

What makes it effective?

Hygrometers are the go-to source for measuring humidity. This tool can be used in laboratories, manufacturing sites and storage vicinities. Even meteorologists use hygrometers to report the most accurate amount of relative humidity in the community. Hygrometers are widely used because they come with hard-to-beat features. Many hygrometers are built with alarms that will alert you when the humidity level in your home is under that 30 percent or over the 50 percent average humidity level.

Hygrometers can serve as a great way to keep you, your family, home and belongings healthy. They can also come with humidistats, which control the operation of your humidifier or dehumidifier.

Recommended Hygrometers

Temp Stick Wifi Temperature & Hygrometer Sensor ($139 Plus Shipping:  Made in the USA, this remote hygrometer is a precise and versatile option to continually monitor conditions in any environment, from just about anywhere. Unlike some wireless hygrometers, it’s extremely easy to set up in just a few minutes and it’s factory calibrated (you can also adjust the calibration if required). It requires only two AA batteries, and users report battery life between six and 12 months depending on usage. You’ll also get an automatic alert if the batteries are low, to minimize any downtime.

ThermoPro TP49 Digital Hygrometer ($7 Plus Shipping):  With highly accurate readings and a wide measurement range, TP49 is the perfect home thermometer to keep your family’s living conditions optimal. Room temperature monitor features a face icon indicator to show the comfort level to ensure you’re always aware of changes to your home/household with just a quick glance.

Extech MO290 Moisture Psychrometer + IR ($529 Plus Shipping):  The MO290 is an 8-in-1 meter that combines a Pin/Pinless Moisture Meter with a built-in InfraRed Thermometer. Additional measurements include: Temperature, Humidity, Grains per Pound, Dew Point, Vapor Pressure, and Condensation Point. Complete with pin moisture probe, 9-Volt battery, and case.  This unit is better suited for contractors and inspectors.

About the author: Joe Fiorilli