Condensing and non-condensing tankless water heaters require the same amount of regular maintenance, which involves cleaning inlet filters, the air filter, a visual inspection and descaling. Maintenance details for each model can be found in the user’s manual which you can download here. 

All water heating products require routine maintenance, and condensing tankless water heaters don’t require any more maintenance than tank style water heaters. Tank water manufacturers recommend flushing the tank every 6-12 months as well as inspection and cleaning of the burner chamber, pilot assembly and air intake