Check the listing for details. 5.28 GPM Condensing Natural Gas Tankless Water Heater 0.86 UEF High Efficiency. Color: Silver, Condition: New. Listed at 503.99 USD. [Save 15% & Dual Heat Exchanger] - With potential savings of 15% compared to non-condensing units, this condensing tankless water heater delivers outstanding 0.86 UEF efficiency, dramatically reducing energy usage and operational expenses. This performance is made possible by an innovative dual heat exchange system, which combines a corrosion-resistant stainless steel condensing heat exchanger with a highly conductive oxygen-free copper heat exchanger, captures and reuses waste heat that conventional units lose, to maximize heat recovery. [5.28 GPM & 114,000BTU] - The ThermoMate instant hot water heater can supply two showers simultaneously, each delivering 105°F water at a flow rate of 2 GPM, based on an inlet water temperature of 65°F. No waiting time, no cold water shocks.