Jandy JXI thermostat calibration?

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spoxta

New member
Apr 28, 2021
4
San Jose, CA
Hi,

I use a Jandy JXI 260 as an external heater for our Hydropool AT14fx swim-spa. We don't have any smart management components.

The combination worked ok for a few years, but over the last 12-18 months, I noticed the water wouldn't get as warm any more.
What I find is that the heater shuts off, because the setpoint temp has been reached (e.g. 102F). However, the water in the spa is significantly colder. Like 98F.

This makes it almost impossible to heat the spa to >100F (I really like 102F) using the heater, because I cannot set a higher temp than 104F on the external heater.
Yes, I could (in theory) use the SPAs resistive heater (~10kW), but it just takes forever.

It feels like the Jandy's thermostat should be recalibrated. Are there any ways to do that?

Thanks for any suggestions.
 
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Check the resistance of the water temperature sensor vs. the temperature.

Also, make sure that the flow is good.

Poor flow can cause the heat to migrate into the inlet.

Can you show the system?


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If the thermistor checks out, you can use a 10K ohm resistor in place of the water temperature sensor to see if the display reads 77 degrees.

Do NOT operate the heater with a resister in place.

This is only a test to determine if the board is reading the resistance correctly.

If the temperature is not 77 degrees, then the board is probably bad.

If the temperature reads 77 degrees, then the board is likely to be good.

Also, check the wiring as it might be damaged due to mice or other causes.
 
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