Good afternoon everyone. I have a spa that waterfalls into my pool. The spa is heated by a Sta Rite SR200 Natural Gas Heater. Here's my problem though. When I activate the heater, the temperature on the heater reads about 30 degrees colder than the actual water temperature. The heater will still heat the pool, but since it thinks it's 30 degrees cooler than it actually is, the heater never turns off. It basically heats the water so hot that I have to manually turn it off and on to try and regulate the temperature. I've already replace the thermistor and high limit switch. The old thermistor looked ok, but I replaced it anyway. The high limit switch was broken. So anyway, both have been replaced, and I'm still having the same problem. Any idea what it could be? Any help is appreciated. Thanks so much.