The second one is not working! (Both WH were installed at the same time and are almost nine years old.) I always thought the first one goes out because it works the hardest. Basically here is the scenario:
Ever since the H/O has lived in the house, the second one's temp has always been set hire than the first. My last visit I informed her that the temp on the second should be reduced. She turned it down to 120. Then they had problems with hot water. I measured the powder room and only got 111. I measured the laundry tub next to the heaters and got 113. I then ran the hot water until there was only cold coming from the first into the second. Guess what? The first burner turned right on and began heating the incoming water. The second burner never even turned on! It was set at 130! I then manually turned up the thermostat and it then began to fire. Bad thermostat? I think so. I gave her prices, and if she calls me to do the work, I informed her I would pipe them in paralell (sp) if replaced.