Keystone Condensing Water Heaters produce high volume hot water with high energy efficiency. These products feature a stainless steel heat exchanger with a thermal efficiency between 95 and 97%. Their compact design minimizes floor space while the cabinet provides easy access to all components. The large user friendly control interface makes set-up easy. The advanced control modulates the water heater with a 5 to 1 turndown ratio. Up to 8 water heaters can be joined in a cascade while the control features parallel modulation and water heater rotation to maximize efficiency and service life.