What is the problem when spa temp showing 100 and actual temp is 90

SOURCE: Spa only gets to about 90 deg

For a quick fix you could swap out the air and water temp sensors. They should be exactly the same.

SOURCE: Sta Rite Sr333na Max E Therm Pool & Spa Heater gauge stuck?

Anytime the heater is reading the water temp to be above what it actually is, especially 126, the problem is the Thermistor, or Temp Sensor, for the heater. This is a very easy part to replace. The Thermistor is located on the manifold, on the left side, between the top two bolts.

Sorry this is a late response! Hope that it helps!

SOURCE: Pential Easy Touch Pool/Spa remote says the water

you can change the calibration on the temp. or how did you check the sensor

We Fix Ugly Pools

• 46 Answers
• Posted on Dec 10, 2010

SOURCE: have pentair easy touch controls just installed

If the Easy Touch is reading the correct temperature, but the heater is not - you need to double check the temperature of the pool water with a standard pool thermometer.
Other things to consider:
1) The water is traveling too slowly through the heater. If the water is heating too quickly, then it will shut it off. If it takes a while for this to occur, then this would not be the issue.
2) Thermostat/thermistor is incorrectly reading the temperature of the water prematurely shutting the system down.
Make sure you really are checking the temperature of the water and matching this temperature up with one of the two readings that you are getting. Don't just take the word of the displays on either unit.

SOURCE: My heater is heating to

Press menu, scroll to settings. There should be a choice labeled "calibrate". You can change the temp reading here.