My Sta-Rite SR333NA was installed in June, replacing an eleven year old unit of the same model. It has worked great all summer. Last night, I was outside when the heater fired, and it's making an awful noise. Turned it off, unplugged it overnight. Plugged it in the next day, and here is what happens: heater seems to boot normally as far as LCD sequence. Blower starts fine. But when the heater fires, it makes this odd loud sound - low, loud, kind of thumping, almost like a subwoofer being overdriven - with a faint grinding noise heard intermittently. No error LED's light up, it just keeps going. The water from the outlets is definitely being heated. But the noise doesn't stop- I let it run for about five minutes, then shut it down as I was worried about causing further damage.
Any ideas? I called my pool guy, but haven't heard back. I'm in Upstate NY so a lot of people are closing their pools right now.
Also - any experience with the Sta-Rite warranty process? My pool guy installed the heater, but I ordered it from poolsupplyworld.com. Again, it's barely three months old.
Thanks for any help!