3 I continue to be impressed by Rheem service. My six year old tankless water heater quit in the middle of a Monday morning shower. I called Rheem the same morning and by noon the next day I had a new (for free) printed circuit board (the black box in this picture) in my hands. By mid afternoon, following detailed instructions, I had carefully disconnected all the wires, put in the new board, reconnected and reprogrammed. Now we have uninterrupted hot water again, I'm hoping for six years plus. All I paid for this repair wa $40 in duty.