Navien’s NPE-A series innovative ComfortFlow® technology incorporates a built-in buffer tank and recirculation pump inside the unit to provide a zero GPM activation rate. Additionally, with the ComfortFlow buffer tank, the “cold water sandwich”, common in other tankless units, is eliminated. With a return line, the pump saves thousands of gallons of water per year. Additional Navien NPE standard features include: dual stainless steel heat exchangers, 1/2” gas lines up to 24’ and 2” PVC venting up to 60’. These technical advances make the NPE-A series ideal for commercial and residential tank water heater replacement as well as new construction.