There is minimal maintenance to keep the water heater running good as new. Here is a quick link to some helpful steps http://www.wikihow.com/Maintain-a-Tankless-Water-Heater
Bathrooms, depending on size and complexity, typically range from $4,000 upwards of $30,000+. It depends on many variables. Are you replacing what you have or changing the layout of your bathroom? ... read more