Navien NPE-24SWE Low-NOx Standard Natural Gas Water Heater The Navien NPE-24SWE Standard Natural Gas Water Heater is a tankless water heating system that is high-performance and reliable. With over 10 years as the No.1 selling tankless water heater in North America, this system is trusted by homeowners and businesses worldwide. Dual stainless steel heat exchangers give maximum performance and durability while reducing energy consumption. The unit delivers up to 24 litres per minute at a 25°C temperature rise, suited to demanding applications. It ships configured for Natural Gas as standard; conversion to Propane (LPG) is possible using a separate conversion kit fitted by a qualified engineer. Up to 16 units can be cascaded with Ready-Link® for increased output, balancing workloads for longer system life. Freeze protection allows operation d