What is the problem with the heater? If it is leaking, probably bad chemistry. Is there a tablet feeder in the system? That kills more heaters than you can imagine. Is it the electronics? That has nothing to do with the water.
It was the heat exchanger - rusted completely and started leaking in 3 seasons. We have a salt water pool and have it professionally balanced all season. No feeder tablet.
Either you have very high water flow, which can eat a heat exchanger, or very bad chemistry, which is more likely. Heat exchangers are copper, they don't rust.
The single-header design of a Hayward heat exchanger makes it susceptible to damage at the other end from flow rates that are too high. Possibilty. A visible inspection can easily differentiate the reason, in most cases.
You are NOT alone. I know that heaters are roughly the same but I had the same issue with two successive Hayward H250 HX's that didn't last 2 seasons each. I use a Taylor kit for my chemistry and am a type A so test my water frequently. I am afraid that there is more to this heater than we know and I have seen posts about dissimilar metal contact in the heater.