I have a Pentair MaxETherm OM pool/spa heater (400,000 btu). About a year ago, when turned on, the blower would start, the burner would fire, but then would immediately shut down. I pulled the covers off and discovered that a pack rat had built a nest inside. Long story short, I cleaned out the nest and got rid of the rat.
After a thorough cleaning and de-ratting, the heater still wouldn't stay on, so the troubleshooting chart led me to replace the blower. The heater worked just fine for a couple of months. Then one evening I was heating up the spa and the temp got up a little over 90 degrees and wouldn't heat any higher than that. The max temp is set at 104, and the desired temp was set at 101. I went back to the troubleshooting chart and it led me to replace the High Limit Switch. I cant recall the specifics because it was probably 9 months ago, but there were other issues that came from the troubleshooting chart that prompted me to also replace the Ignition Control Module. Again, once those new parts were installed, the heater worked perfect.
But a few months later, I suddenly had the same problem. The heater would heat up to 95 and then stop and hold at 95. I replaced the High limit Switch this time and it worked like a champ...for about a month . Back to heating up to 95 and holding there.
Does anyone here have any idea what might be causing my High Limit Switch to burn out every couple of months?
Thanks in advance.