My 6.5 year-old gas hot water heater (50 gallon A.O. Smith) has started running out of hot water after 15 minutes or so. My plumber (from a large company in NY) came out and just turned the temp up. When that didn't work, I spoke to the owner of the company, who told me it was probably recirculating warm water at the top and not heating the whole tank. He said it would probably just be better to replace it than repair it. And, of course my parts warranty expired 4 months ago (tank warranty is still ative)
Does this sound like an accurate diagnosis? What can I do to confirm the problem?
Thanks for any help,