While trying to diagnose an issue with my hot water tank, I disassembled it and took a photo from the inside where the burner is normally located, pointing upwards at the exhaust vent.
It seems that there is some metal object inside the vent. What is it?
It appears to be a flue baffle. Many gas-fired water heaters have these inside the flue way to slow the movement of the flue gases (ie the heat produce by the burner) and improve the transfer of heat from those gases to the water tank.
Here's a photo of one that is offered as a replacement part for Rheem water heaters on Rheem's web site.
