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What Is a Humidifier Solenoid?

By Paul Scott
Updated: May 17, 2024

A humidifier solenoid is an electromagnetic actuation device used to open the valve supplying water from the reservoir of the humidifier to its evaporator mechanism. The solenoid coil is wired into a control circuit that senses when the atmospheric humidity requires replenishment. When this occurs, the control circuit supplies power to the coil, opening the valve and activating the evaporator. Humidifier solenoid failures will cause the device to cease working, but are fortunately not exorbitantly expensive to rectify. Unqualified users should, however, not try to replace a faulty solenoid themselves as they often carry mains power and may pose an electrocution hazard.

Humidifiers are devices used to add humidity, or airborne water vapor, to a closed atmosphere. Low humidity can cause a range of health and structural issues in homes or offices necessitating the use of a humidifier. There are several types of humidifier in general use including steam, impeller, and ultrasonic types. Although their internal mechanisms differ considerably, they all consist of several common elements. These include a reservoir, a evaporator mechanism, and a humidifier solenoid valve.

The operation of a humidifier is fairly simple, with a reservoir containing water feeding an evaporator unit via a solenoid valve. The evaporator causes the water to be released into the atmosphere in the form of fine droplets that become suspended in the air restoring an acceptable level of humidity. The water is not fed to the evaporator constantly with the humidifier solenoid valve remaining closed until the atmospheric humidity drops below a set level. The valve is little more than a standard water solenoid valve switched on and off by a control circuit equipped with a sensor known as a humidistat that reacts to the ambient atmospheric humidity level.

Faulty humidifier solenoid valves are a common cause of humidifier failures, as the unit will not work at all if the valve does not open or function incorrectly if it jams open. Luckily, the solenoids are not overly expensive to replace or repair. It should be noted that, although many humidifier solenoid valves carry low voltages in the 12- to 24-volt range, they may be powered by mains voltages. Anyone not possessing the required experience runs the risk of potential electrocution should they attempt to replace or repair the solenoid themselves. As with most electrical devices, it is always better to enlist the services of a qualified service technician to do the job, particularly if the device is still under warranty.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
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