Ultrasonic humidifiers are filthy and eventually crap our. I average 3-4 years out of them. Best to buy one that integrates with your furnace and I would not recommend the evaporative ones that blow air against a water panel (most Honeywell are like this.) I’m talking about one with a small boiler than injects steam into the ducts when the furnace is running. The one I have is Aprilaire brand in the US.