The Rinnai 106000016 Water Heater Combustion Chamber Sight Glass Plate provides a viewing point for inspecting the burner flame inside the combustion chamber. This replacement component is designed to fit over the designated inspection opening, creating a protective barrier while maintaining visibility of the burner area. It allows technicians to observe the combustion process without... https://www.hnkparts.com/106000016-rennai-combustion-chamber-sightglass/4-106000016.html