Jandy JXI 260P High Flue Temp

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smartatx

New member
May 12, 2025
3
Austin
Pool Size
21
Surface
Plaster
Chlorine
Liquid Chlorine
My spa was working fine one evening, the next is would not heat. I checked and the display showed Fault High Flue Temp and does not turn on at all. I've removed the cover to inspect and do not see any indications of leaking around or on the heat exchanger combustion chamber. I also removed the ignitor and inserted a borescope to inspect. Did notice some light scaling but no significant build up (compared to what I've seen in other post online) and no water appeared to be in the tub. (not the best still picture)
Image20250515115648.jpg
I'm not seeing any water leaking at manifold either. I plan on replacing the Flue Sensor but do plan on performing a couple of items prior to doing so.
  1. Remove Exhaust Elbow Assembly in an attempt to gain better visibility and possibly vacuum out what I can from the combustion chamber/tub.
  2. Inspect/clean Exhaust Elbow Assembly.
I do have a couple of questions.
  1. If I wanted to fully inspect and clean the combustion chamber, is it as simple as
    1. Turning off gas and power
    2. Disconnecting gas line (coupler)
    3. Remove lid by unscrewing band clamp (or if needed removing Exhaust Elbow Assembly, Ignitor and Blower Assembly/burner) and then have access to chamber/tub?
If all else fails and this does not fix the issue, my other option (outside of full heater replacement) would be to replace the Jandy Heat Exchanger and Header Assembly R0805803.

TIA for any thoughts/suggestions/feedback?
 
Last edited:
Welcome to TFP.

High flue temperature is often a water flow problem.

Show us your entire system.

What is your filter PSI?

Remove the cartridges from your filter and see if your heater runs fine without them.
 
smartatx said:
My spa was working fine one evening, the next is would not heat. I checked and the display showed Fault High Flue Temp and does not turn on at all. I've removed the cover to inspect and do not see any indications of leaking around or on the heat exchanger combustion chamber. I also removed the ignitor and inserted a borescope to inspect. Did notice some light scaling but no significant build up (compared to what I've seen in other post online) and no water appeared to be in the tub. (not the best still picture)
View attachment 646241
I'm not seeing any water leaking at manifold either. I plan on replacing the Flue Sensor but do plan on performing a couple of items prior to doing so.
  1. Remove Exhaust Elbow Assembly in an attempt to gain better visibility and possibly vacuum out what I can from the combustion chamber/tub.
  2. Inspect/clean Exhaust Elbow Assembly.
I do have a couple of questions.
  1. If I wanted to fully inspect and clean the combustion chamber, is it as simple as
    1. Turning off gas and power
    2. Disconnecting gas line (coupler)
    3. Remove lid by unscrewing band clamp (or if needed removing Exhaust Elbow Assembly, Ignitor and Blower Assembly/burner) and then have access to chamber/tub?
If all else fails and this does not fix the issue, my other option (outside of full heater replacement) would be to replace the Jandy Heat Exchanger and Header Assembly R0805803.

TIA for any thoughts/suggestions/feedback?
Click to expand...
Welcome to TFP! Removal to inspect the combustion chamber is very involved. I think there are a lot of good videos of this online. Luckily I don't think you need to do this. Nothing you have indicates replacement of your heat exchanger is needed. I think the flu temp sensor is a fusible link so once it fails you have to replace it. Make sure there's nothing in the flu obstructing exhaust gas flow. It has to get very hot to really burn the link up. How old is this unit?

Please send a photo of the error message you get and higher level photo. No idea what your photo above is. I think it's too close. Took another look and OK I'm guessing this is inside of chamber with your boroscope. If you don't see water in the chamber there's probably no reason to open it up. Please do send a photo of the error message.

I hope this helps.

Chris
 
JXi Revision is first letter of serial number.

Note. For use on JXi™ heaters only.

If installing on JXi Revision* G and earlier you will need both R0719400 Electronic Flue Sensor and R0719500 PIB.
 
ajw22 said:
Welcome to TFP.

High flue temperature is often a water flow problem.

Show us your entire system.

What is your filter PSI?

Remove the cartridges from your filter and see if your heater runs fine without them.
Click to expand...
16psi.
Tried replacing the Flue Sensor. When I turned everything back on, sounded like a quick click and then the "Fault High Flue Temp" reappeared.
 

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Smart,

The only additional info I can add is to encourage you hang in there. Trouble-shooting these heaters can be frustrating. And it's not just Jandy they all use very similar (identical in some places) controls. It's also very beneficial to trouble-shoot as you are doing to logically find the fault. Many owner come here after replacing many of the parts at very high cost with little or no investigation. Usually the more difficult issues are related to Flame Sense technology. Yours is likely connections, sensor, or board. I'm clearly not up to date with this sensor but if there's a way to emulate a "safe" state you might be able to try that. Many sensors can be bypassed but quite a few are more complex. This sensor is probably a variable resistor temp sensor and you'd have to find out the resistance to put in to test it. The problem with documenting this by the manufacturer is there are, I'll say this kindly "not so smart" DIYers that will leave it in this test instead of repairing it. Manufacturers can't afford the liability this causes. You're dealing with an area of safety protection on this heater that's very serious business. I think it's very likely the problem is one of the items @JamesW has highlighted plus connections. So the approach I'd use is to double check all connections in the system first. Then test the resistance of the old temp sensor and the new one. If they're close check them both in very hot water. This would indicate to me they're likely good and point toward the board as @JamesW indicates. You really have to gut it out yourself because most authorized repair technicians will only tell you you need to replace the unit. When I looked at the cost of replacing the parts even if I replace a few that were not really the cause it was way cheaper than buying a new heater.

Let me lastly ask, did you by chance have a lightning strike recently? If so, that's a whole different ballgame and still recoverable though.

Chris
 
So with the new Flue sensor installed (Genuine Factory Part), I reset the load defaults and was able to get the unit to start and fire up. I did notice through the sight glass that the flame was yellow/orange in color, which to my understanding could indicate incomplete combustion. Could this still be sensor related? All connections appear to be fine.
 
smartatx said:
I did notice through the sight glass that the flame was yellow/orange in color, which to my understanding could indicate incomplete combustion. Could this still be sensor related?
Click to expand...
A sensor does not cause incomplete combustion.

You either have too little air or too much gas flow.

Check gas pressures with a manometer.

Check the air blower for proper operation and amps.
 
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