The Viking T Plate style wholehouse humidifier is a very simple unit. It consists of a water line, water tray and T shaped humidifier evaporation plates. Those humidifier plates must be replaced at least twice per heating season to keep your Viking humidifier working to its fullest capacity. Since Viking is no longer in business we found the General number 800 plates are the only T style humidifier plates still made that will work in your Viking humidifer. Should you need to replace your entire Viking humidifier the General humidifier shown below is a simple replacement for it.