Glad this is out of the way. The two young service techs who came were very friendly and competent.
I asked them how long a tank usually lasts and they said that the average lifetime of a gas hot water tank is between 12 to 15 years and once in awhile, they will last 20 years, if not overly used. Ours was 15 years old and starting to run out of hot water quickly. Fortunately, it didn’t spring a leak like our last one did.