When we buy new device such as Aprilaire 558 we often through away most of the documentation but the warranty.
Very often issues with Aprilaire 558 begin only after the warranty period ends and you may want to find how to repair it or just do some service work.
Even oftener it is hard to remember what does each function in Humidifier Aprilaire 558 is responsible for and what options to choose for expected result.
Fortunately you can find all manuals for Humidifier on our side using links below.