Navien expanded its condensing tankless NPE water heater series with the addition of the NPE-150S model. This tankless water heater has a heating capacity of 18,000 to 120,000 Btu per hour. It produces 5.3 gallons per minute at a 45-degree temperature rise. Navien says the NPE-150S works best in small residences or to cascade where more domestic hot water is required. The NPE-150S also has a ½-inch gas pipe capability, a 2-inch PVC venting up to 60 feet and dual stainless steel heat exchangers. Navien adds that the tankless water heater features easy-to-use controls and cascade capabilities without external controls.