This unit has a Girard tankless water heater which was a big selling point for us. With four girls, there was seldom hot water for me. The first few showers were terrible, too hot or too cold, on and off. We read the manual, it said use full hot and add cold to temp. Didn’t work. We tried the Low setting which was better but still erratic, then it would occasionally stop working all together.
Upon inspection I found the unit not igniting and the fan wasn’t running. I fiddled with the two wires going to the microswitch (connected with blade connectors) that tells the unit the fan is moving air and it immediately started. They looked slightly corroded.
I cleaned them with WD-40 and switched the unit to Auto. It works well now. I will coat the connectors with dielectric grease when I get home to prevent future corrosion.