Homeowners can come across different issues depending on the type of tankless water heater they have - for gas ones, the burner may get clogged and cause hot spots to burn the heat exchanger. For electric ones, the heating element may need to be replaced if it is acting up.
Rico is a solid hvac service technician. He was thorough, professional and competent. He pointed out things that I never knew before. Also, he took his time and didn't fly out of here in 15 minutes like some other techs...