Pool Water Temp Sensor

[Semi-retired]

All of a sudden started reading high by about 20 degrees?

 

[ajw22]

The sensor can be tested with a multimeter. It should read 10,000 ohms at 77F (25C) degrees. You can lookup other test values in the Temperature vs Resistance Conversion Chart for 10k Thermistors.

Temperature Sensors - Further Reading

www.troublefreepool.com

https://www.troublefreepool.com/wiki/images/1/1c/10K_thermistor_chart.png

 

[Semi-retired]

The sensor can be tested with a multimeter. It should read 10,000 ohms at 77F (25C) degrees. You can lookup other test values in the Temperature vs Resistance Conversion Chart for 10k Thermistors.

Temperature Sensors - Further Reading

www.troublefreepool.com

https://www.troublefreepool.com/wiki/images/1/1c/10K_thermistor_chart.png

Thanks, will do. But I thought these sensors either worked or not...maybe with a little drift over time. It is just odd, to me, that it suddenly jumped up by 20 degrees. It still responds to temp changes but at a roughly + 20. I just wanted to make sure it isn't my EasyTouch control system misreading the sensor. In any case a new one arrives today (Amazon is often amazing).

 

[ajw22]

But I thought these sensors either worked or not...maybe with a little drift over time.

The thermistor varies its resistance based on the temperature.

It is just odd, to me, that it suddenly jumped up by 20 degrees. It still responds to temp changes but at a roughly + 20.

That is a resistance decrease of 4,000 ohms to indicate an increase of 20 degrees.

I just wanted to make sure it isn't my EasyTouch control system misreading the sensor.

The EasyTouch just uses the resistance it sees connected to the board.

You can connect a 10K resistor to the EasyTouch board to test if the board reports a temperature of 76F. If it does not then there is a problem with the board.

In any case a new one arrives today (Amazon is often amazing).

Let is know what you find out.

 

[Semi-retired]

Thanks again. I'm now a bit concerned...the disconnected resistance shows about 7500 which is pretty close to the actual water temp of about 88. Not sure if there is anything else I can troubleshoot before the new sensor arrives. By the way, this is the same type of sensor as the air one that is also installed, I believe (they look identical). And, both the Air temp and the Solar temp (up at the solar panels) are connected to the same terminal block and working fine?

And, oddly enough, with panel power off, while the sensor wires were still connected to the terminal block, the resistance reading was around 4800 which would closely match the displayed temp of 108?

 

[ajw22]

Thanks again. I'm now a bit concerned...the disconnected resistance shows about 7500 which is pretty close to the actual water temp of about 88. Not sure if there is anything else I can troubleshoot before the new sensor arrives.

You can connect a 10K resistor to the EasyTouch board to test if the board reports a temperature of 76F. If it does not then there is a problem with the board.

By the way, this is the same type of sensor as the air one that is also installed, I believe (they look identical). And, both the Air temp and the Solar temp (up at the solar panels) are connected to the same terminal block and working fine?

All three temperature sensors are identical.

And, oddly enough, with panel power off, while the sensor wires were still connected to the terminal block, the resistance reading was around 4800 which would closely match the displayed temp of 108?

You can connect a 10K resistor to the EasyTouch board to test if the board reports a temperature of 76F. If it does not then there is a problem with the board.

 

[Semi-retired]

Thanks again, will report back after testing with new temp sensor. I have a lot of stuff in my workbench, but no 10K (or any) resistors, lol.

 

[Semi-retired]

See photo...mystery solved...very failed sensor