Customer called in because he was not getting any hot water. Upon arrive found that customer has Navien Tankless. No errors codes displaying. Tested tankless and was getting hot water 50% of the time. Checked water screen filter and it was semi dirty. Checked air filter and it was completely clogged. After cleaning both filter tankless fired up each time. If problems persist, it’s going to be the foe sensor of tankless. Also noticed that condensation is dumping right below the unit. There’s an improper install on condensation line. Brass fittings were used instead of pvc. Customer will monitor tankless over the weekend and if problems persist then he will move forward with repairs.