I hope someone can help me here. My pool heater is 3yo and has never had a problem. I use it maybe 3-4 times/week, on average maybe 60 minutes at a time, and live in sunny So Cal (no freeze/cold weather issues). It's never given me a problem and worked fine until last Tuesday, just before a week long, non-stop rain storm. I tired using it last night, but the heater will not fire. The heater unit powers up ok, but the LED readout just keeps reading 114 degrees. The LED temp reading changes a degree or two with increases and decreases in filter pump pressure. Eventually it stabilizes at 114. I have checked all diagnositics (per the manual), whereby no codes or lights are blinking or staying on. As a side note, upon immediate startup I do get a quick LED r=5 code (no flame, which is obvious). I removed the thermal regulator, which was in good condition and works fine (I checked with +150 degree H20). I have always been Very attentive toward the maintenance and pool chemisty and clean my filter pump and my DE filter regularly. I recleaned the DE filter again today. Could this problem be the Thermistor? Could this past week's very heavy rain caused damage to the unit? As I said, it doesn't appear to be an electrical issue. Any other ideas?

Pool & Spa - Pentair - MASTER TEMP HEATER 400 000 BTU NG LOW NOX HD EXCHANGER