I have aa Aero RF-50 oil fired water heater rear/side exhaust. It is 10 years old. I read that I should be inspecting the Anodes and replacing if necessary. I have taken the top off of my heater and removed the insulation. All that I find is a solid Steal cover. I was looking to find a couple of 1and 1/16th nuts that are the Anodes. Where are the anodes on this model? Where are the Anodes