The cost to install whole-house humidifiers can range anywhere from $400 to $750. The highest installation cost is reported as $1000 in very rare cases when the area of installation is a bit complex. While getting it installed, remember that your total cost may be influenced by the type of whole-house humidifier you are installing. Installing steam-type humidifiers can be a bit more expensive than compared to other types. It is best to get a rough estimate from 2 to 3 different professionals and choose the one who is most reliable and affordable.