The Navien 30020563A Natural Gas Heat Exchanger is a genuine replacement component designed for compatible Navien NR and NP series tankless water heaters, including select 210A and 240A models. It works by transferring heat generated through natural gas combustion to the incoming water, providing an efficient supply of hot water on demand. This essential component supports reliable he... https://www.partshnc.com/30020563a-navien-tankless-water-heaters-natural-gas-heat-exchanger