[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, perfect for busy households. Adopting advanced water flow sensor, the built-in chip can adjust the heating power 20,000 times per second, ensuring that the hot water within ±1℉ fluctuations for a comfortable shower experience. [Safety & Reliable] - This natural gas tankless water heater integrates 8 protections: boil-dry, freeze, flame-out, overheating, over-temperature, pipe blockage, high-temperature lock, and excessive air pressure. Equipped with 4 ceramic heating cores, it auto-activates frost protection when temperatures hit 41°F (5℃). The energy-smart system uses minimal electricity to generate gentle warmth, preventing pipe ice buildup without high energy costs. [Smart Diagnostic Display] - Equipped with a 3.5-inch LED touchscreen, it allows you to effortlessly adjust and monitor output water temperature（90°F to 140°F）while providing real-time tracking of water flow, fan operation, and flame status. Advanced error code technology enables rapid diagnosis of water heater malfunctions. The UL-certified 120V/5-foot power cord ensures continuous power supply for real-time monitoring systems. [Discharge and Treatment of Condensate Water] - As a condensing unit, this water heater produces mildly acidic condensate water that you will need to discharge into a drain. We recommend installing an economical external condensate neutralizer kit (not included) at the drainage point. This simple add-on neutralizes the acid, protecting your pipes from potential corrosion. [Easy to Install & Save Space] - The indoor residential tankless hot water heater features standard 3/4" NPT water inlet/outlet connectors, a 1/2" NPT gas inlet, a 3" OD vent, and a UL-approved 120V plug, ensuring compatibility with most households, and with compact dimensions of 21"H x 13"W x 7"D, requires less than one-third of the space of traditional tank models, freeing up valuable room in your home. ThermoMate CZ480NG 5.28GPM Condensing Tankless Water Heater, 0.86 UEF High Efficiency Instant On-Demand Hot Water Heater, Residential Indoor Natural Gas Water Heater with Multi-Point Heating