You bought a house two years ago and the hot water heater just
died. You are considering replacing it with an updated version of
the same model, which would cost you $200 including installation.
Your family consumes about 110 gal of hot water daily, which costs
you $230 in utilities each year. The new tank comes with a 20-year
guarantee, and at the end of that time, you assume it would be
discarded and a new version installed, so zero...