How often does a Gradient syncFURNACE need to be serviced?

Once a year, by a professional. Gradient’s manual requires the burner and combustion chamber to be cleaned annually, the condensate line and trap cleaned semi annually, and the flue, air intake, igniter and flame sensor checked annually. Gradient also tells homeowners to have a contractor perform annual maintenance including a filter change and water system flush and descaling. The condensate trap should be inspected quarterly.