Mastertemp 400 wrong temp reading

[esolm]

We have an in ground pool with hot tub. We have a mastertemp 400. We recently had a stack flue sensor error. I replaced the sensor. At the same time we have had an issue with the hot tub heating to about 95 (automation temperature) but the screen of the mastertemp says 102 and it then shuts off.

I have now replaced the stack flue sensor, the thermistor, and the flow sensor. The issue continues. The temp on the mastertemp shows 102+. The temp on the automation panel shows 95. The heater turns off.

What should I look at next?

 

[ajw22]

Welcome to TFP.

Segal’s law - “A man with a watch knows what time it is. A man with two watches is never sure.”

Measure the spa temperature with a cooking thermometer.

I suspect your automation water temperature sensor is off.

What model automation are we discussing ?

Temperature Sensors - Further Reading

www.troublefreepool.com

 

[1poolman1]

We have an in ground pool with hot tub. We have a mastertemp 400. We recently had a stack flue sensor error. I replaced the sensor. At the same time we have had an issue with the hot tub heating to about 95 (automation temperature) but the screen of the mastertemp says 102 and it then shuts off.

I have now replaced the stack flue sensor, the thermistor, and the flow sensor. The issue continues. The temp on the mastertemp shows 102+. The temp on the automation panel shows 95. The heater turns off.

What should I look at next?

Is the temp on the heater set to 102? If so set it to 104 (max) and allow the automation to control it after you replace the water-temp sensor. If you do as ajw22 suggests, you will probably find that the water is 102 and it is the heater that is turning off 0n its own, not the automation turning it off.