A new, high-efficiency boiler is a good match to an indirect WH. I had them install the SS Ultra (the SS version). In theory, it should last a very long time. Note that you typically can get by with a smaller tank than a typical electric because when they set the thing up, they normally make the WH a priority zone, so when needed, it gets the entire output of the boiler which is usually a lot larger than any electric tank you can reasonably buy. This means it can heat the incoming water and give more gallons in the first hour than either an typical electric or gas-fired WH.