Jandy heaters with automation

Aug 31, 2018
41
League City Tx
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Hi, I have a jandyystem with aqua link, aqua pure SW system, and jxi heater, circa 2018.

I’m troubleshooting heater issues. One is the High limit fault, which is causing the heater to cycle on and off. I know to replace the limit switches. That is, unless there is a true issue causing a high temperature, which I don’t know how to diagnose.

The other issue is erroneous temp readings. I turned on the heater earlier; in aqua link the water temp showed 70, but the heater display was showing 91. I came back after a while and aqua link showed 88, heater showed 112 with a high water temperature warning. Checked the aqua pure temp from the salt cell and it matched the aqua link readout.
To further diagnose, I took out the jxi water temp sensor, and disconnected the wires from panel to check resistance. Air temp was 68°, as read from the aqua link air sensor, and the heater probe resistance was 12.45k ohms. Based on the charts I found, that should be consistent with 68°. Seems ok I guess

Put it back together and fired up system again. Water temp on jxi, aqua pure, and aqua link more or less match within 1-2° of each other(~80). After a few minutes I got the first high limit fault, but as I mentioned, the heater will cycle back on after a minute.
I noticed again, that as the water temp was rising, with matching indicators from aqua link and aqua pure, the jxi temp was increasingly off on the high side(85 vs 105).

All that said, I plan to replace the limit switches and the temp sensor. Am I missing something? I was also curious how the “remote thermostat enabled” goes into the automation equation. Pool builder told me that the heater uses the remote thermostat, I believe from the aqua link sensor at the pump, as the control. If that’s true, why would the sensor on the jxi have any effect on heater function?

If you made it this far, thanks for taking time to read.
 

A bad Thermal Regulator valve in the water header can cause high limit faults. Check the Thermal Regulator before replacing sensors.

I was also curious how the “remote thermostat enabled” goes into the automation equation. Pool builder told me that the heater uses the remote thermostat, I believe from the aqua link sensor at the pump, as the control. If that’s true, why would the sensor on the jxi have any effect on heater function?

The Aqualink acts as the remote thermostat cycling the JXI on and off as needed based on the Aqualink water temperature.

The JXI temperature sensor is still used when in REMOTE TSTAT mode to ensure the heater stays within its temperature limits. The JXI temperature will not go above the set point in the heater control panel. So that must be set to the maximum of 104F.

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Thanks for taking time to respond. I appreciate the info on how aqua link and the jxi temp sensors are used, makes sense.

I do think I may have a bad water temp sensor given the erratic behavior, but I am going to start researching the thermal regulator you mentioned, and diagnostic methods. Thanks!
 

A bad Thermal Regulator valve in the water header can cause high limit faults. Check the Thermal Regulator before replacing sensors.



The Aqualink acts as the remote thermostat cycling the JXI on and off as needed based on the Aqualink water temperature.

The JXI temperature sensor is still used when in REMOTE TSTAT mode to ensure the heater stays within its temperature limits. The JXI temperature will not go above the set point in the heater control panel. So that must be set to the maximum of 104F.

View attachment 621955
So I replaced the thermal regulator valve and no long get high limit faults; the valve was rusted.

I am still getting erroneous temperature readings from the heater sensor. This morning it also gave a shorted h2o sensor fault.

I got a 10k ohm resistor(tested and it read 9.88) and installed to the heater board in place of the temperature probe wires. The heater now reads 78° which matches the charts. I take this to mean the board is fine, and sensor is bad. Correct?

Any issues letting the heater run like this until I get a new sensor tomorrow?
 
I got a 10k ohm resistor(tested and it read 9.88) and installed to the heater board in place of the temperature probe wires. The heater now reads 78° which matches the charts. I take this to mean the board is fine, and sensor is bad. Correct?

Correct. Replace the sensor.

Any issues letting the heater run like this until I get a new sensor tomorrow?

Your Aqualink should control the heater but keep an eye on it as you have disabled one of the safeties to keep it from over temping and melting down.
 
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So I replaced the thermal regulator valve and no long get high limit faults; the valve was rusted.

Glad we can help.

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