I have a Pentair Mastertemp 125 heater that was purchased last June. It was used for 7 weeks last year and 2 weeks this year and has now stopped working. It starts fires up and then quits, no codes. Repair man came out checked the pressure switch which he said was ok and said that heater is overheating, pool water is out of balance, heat exchanger is most likely full of calcium deposits and basically throw the heater away, warranty not valid. Is this possible? Is there anything I can do to try and fix this? I just paid almost $1000 to just throw it away !