How They Work
Generally, air humidifiers have a bypass flow-through style that uses a pipe to bring water directly to an electrically controlled valve at the top of the humidifier. Air passes through an aluminum pad (often called a biscuit; the term “biscuit” emphasizes the solid rather than foamy form). The pad has a coating of ceramic, resulting in an extremely large surface area within a small space. When the humidistat calls for humidity, the valve is opened and causes a spray of water onto the pad. Hot air is passed through the pad, causing the water to evaporate from the pad and be carried into the building.


Advantages Include:
- Reduced maintenance (new pad is needed only when clogged with dust or mineral deposits, typically once per year)
- Lack of a pan of potentially stagnant water to serve as a breeding ground for mold as with a drum-style humidifier
- No incidental humidification caused by a constantly replenished pan of water in a high velocity air stream
- Reduced requirement for expensive air filters
- Uses little electricity