Hello,
My 'Leisure Bay' Spa circa 1989 is tripping the reset buton on heater unit at about 90 degrees. The rest of the spa is fully operational with power. The heater mfg. is Vulcan with serial # EHHVUL101.
Thanks

Either the high limit switch is tripping because it's ancient, or the heater really is overheating due to a flow problem.

I don't trust these systems as far as I could throw them once they get this old.