The answer to 'how much to replace humidifier' is that the cost to replace a whole-home humidifier can vary significantly depending on several factors. As a general range, you can expect to pay anywhere from $300 to $800 for a new whole-home humidifier, including the unit itself and professional installation.
The exact cost will depend on the size and type of humidifier, the complexity of the installation, and your local labor rates. Larger or more advanced models with additional features will be on the higher end of that range. Additionally, if any ductwork or plumbing modifications are required, that can also increase the overall replacement cost.