Heater screaming like a banshee'

[I-D-10-T Error]

I have a Raypack pool heater about 5 years old. This year when I fired it up, it makes all sorts of screeching, whining, screaming noises. Worked fine until the other day, the Roll out switch is potentially shot. I have ordered a replacement. In my reading, I saw that rollout could create an issue, but can find no evidence of flame etc; I took the heater apart, all looks pretty clean for a 5 year old heater. I run the pool year round, and our water is as hard as 30 minute moonshine...I put Scaletec in the pool on occasion but not sure how much it helps. We only use the heater 2-3 times in the spring. I have a 1.5 HP pump, 2" plumbing and good circulation in pool. I have not tried "recirculate" on Pentair valve, but may try it after I get the switch installed. Should I try messing with the return flow or have the regulator valve tested that is mounted right before the heater? could the water tubes in the heater be so closed down with calcium that the circulation is an issue???Thanks for any response...

 

[Bama Rambler]

The noise you describe is usually caused by a faulty or scaled internal bypass valve.