I recently bought a house that came with a Pentair MiniMax 300DV propane gas heater for a 15k gal pool/spa combo. It's not working currently, I just get a general "error" on the front panel and plan to have it looked at and fixed. But the unit itself looks pretty rusty on top. It's probably 7-8 years old. What is the lifespan of these things? What typically breaks first, the electronics or some other hardware?
I'd like to replace it with an electric heat pump since propane costs almost $5/gal in my area, plus I live in Orlando where it's warm enough year round for the HP to work efficiently, but I'd rather not spend the $4k converting to electric right now. I want to see what kind of propane bills I wind up with (I know it's going to be high). In any case, I'm sure the unit is out of warranty, but still wondering about how long they should last.