Out here, a hot water setup has more pieces to it than it does in town. Plenty of properties run on propane instead of a gas main, some are on well water, and the far bathroom can be a long way from the unit.
Mineral heavy well water can scale a heat exchanger faster than town water does. A propane unit has its own needs when it comes to supply and pressure. When a code shows up, either one can be behind it.
Someone comes out, looks at the unit and what it's connected to, and gives you a straight answer without any runaround. If it's a repair, that's what you'll hear. If it's time for a new unit, it gets sized for your property.