Standard, flow through humidifiers are by far the most commonly installed humidification product, popular for their affordability and reliability, and healthy to use in our dry Colorado climate.  Water is evaporated across a pad in the humidifier and your furnace delivers the moistened air into your home.   Because these humidifiers need the heat to be running to be most effective, a consistent moisture level is difficult to establish and maintain.  Performance can be less than fully satisfactory, especially in larger homes.

Steam humidifiers are ideal when you want to be sure to establish a consistent humidity level in your home.  Steam models boil water, and while they still use the furnace fan to deliver the humidity, they don't need the heat to running to be effective.   Steam humidifiers are more costly to install, more maintenance intensive and less reliable, important considerations if you choose this more effective option.  But when you know you want consistent humidification, especially if your home is larger, a steam model may be your only effective choice.