The Rinnai 104000022 Water Heater Flame Rod Kit detects the presence of a burner flame to support safe and consistent water heater operation. The flame rod works by sensing the electrical current produced by the flame and sending a signal to the heater's electronic board, which verifies combustion during operation. This component is used in compatible Rinnai tankless water heater mode... https://www.hnkparts.com/104000022-rennai-kit-flame-rod-kt/4-104000022.html