The Navien water heater parts include a dual stainless steel heat exchanger, burner, igniter, pressure relief valve, fan, control panel, temperature sensor, and water flow sensor. Navien water heater parts are made with high intelligence technology with multi-line controls, dual venturi for field gas conversions, comfort flow, etc. https://www.partshnc.com/m/navien-tankless-water-heaters/navien-water-heater-parts