The answer to 'lifespan of humidifier' is that the average lifespan of a whole-house humidifier is 8-15 years with proper maintenance. Portable humidifiers typically last 3-5 years. The lifespan can vary depending on the type of humidifier, how often it's used, and how well it's maintained.
Whole-house humidifiers that are properly cleaned and serviced annually can last on the higher end of that range. Portable humidifiers may need to be replaced more frequently, especially if they're used daily during the winter months. Proper cleaning and maintenance is key to extending the lifespan of any type of humidifier.