The rule of thumb our plumbers use is simple. If the heater is under eight years old and the repair costs less than half the price of a new unit, repair it. If it is older than ten years, is leaking from the tank itself, or has needed more than one repair in the past two years, replacement is usually the better use of money, because a new unit is more efficient and comes with a fresh warranty. We will tell you which category your heater falls into and what each option costs before you decide; there is no pressure either way.
We also do not chase trends. Some newer designs on the market are more complicated than they need to be, and complicated means more that can fail in year six. We install what we have seen hold up in Central Oregon homes over 20 years and can service with parts on the truck.
For homes on a well or with older galvanized supply lines, we also check water pressure and the pressure-reducing valve, since excess pressure shortens a water heater's life and can void its warranty. Bend's freezing temperatures add one more consideration: heaters in unheated garages or crawl spaces work harder and should have insulated supply lines.