MY A.O.Smith FPS40, a NG Power Vented Unit is now leaking profusely out of the bottom of the tank, a trail of trickling HOT water escapes the lower shroud near the front pilot access door and trails down to the concrete floor beneath the metal seat on which the whole unit sits. I can't complain. It has a tag indicating a December 1993 install. I moved here in '04. I've done minor repairs (PRV and flushes), never changed anything else but, I realize that this leak is not a good sign. Will someone please advise me regarding what I should know before I start shopping? Do I need to measure the height from the floor to the connection for the exhaust? I'd like to use the original venting from that point through the basement wall near the ceiling if possible. I want to do this myself since I know I can as long as I can find a gorilla to help me get it down in the basement. I turned the water and Ngas back on, this evening just long enough to take a shower but, I don't know if this thing to rupture and spill water all over my basement or not so I shut it off again after my shower. How can I not go with another A.O. Smith, at this point? Any recommendations for a replacement unit? I'm sticking with NG, maybe 50 or 55gal., max. and the power vent system was somehow required for my home back then, I assume, so I'll stick with that, as well.