Jandy JXI Heater Flue Temp High

rdf123

Member
May 29, 2017
13
Ancaster, Ontario Canada
Hello,

I have a Jandy JXI260N heater, that will not start. It has a Fault High Flue Temp message as soon as it boots. I have jumped out the flue temp sensor with a wire, thinking it will either be open or closed depending on the sensor temperature. It does not have a fusable link in the flue. It is part R0719400. 2 wires come out of it. It was open when i ohmed it out so i figured i could just jump out the sensor as normally closed and things should work. It did not. I have a red LED on solid and D1 blinking and D3 solid both green. My manual does not show this error code. Heater was running all morning and quit at some point this afternoon. When i reboot, i get a quick buzzing noise from the electronics area and then nothing. Flue is completely clean and unobstructed. It is outdoors so no venting at all. I am assuming that the sensor has gone bad and it is not just a high/low. Any suggestions? Not sure what to do next. I have ordered a new sensor already, just waiting for it to come in, thought there may be a way to bypass. Thx20220528_150954.jpg

 
Last edited:

Poolbreh

In The Industry
Jul 31, 2021
949
San Diego
You can check 24vac between terminals with jumper attached. You can also try clearing the memory to default settings by holding all three buttons down for 7 seconds and scrolling through menu. Sensor should only be jumped for testing short period of times. The the high flue sensor could have been triggered by underlining condition with the transfer of heat to the heating element. Let’s see what @setsailsoon says he built a jxi from scratch.
 

rdf123

Member
May 29, 2017
13
Ancaster, Ontario Canada
Ok, I cleared the error and got past it, now I am getting an ignition lockout error on the Fenwal module. It tried to light but does not. I can smell the gas. After 3 tries it throws the error and then nothing.
Tested the resistance across the flame sensor...wide open. took it out and the outer coil is broken...that may be the issue. still don't know why I got the initial code of Flue temp to high though
 
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setsailsoon

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Jandy changed flue gas temp sensor from a fusible link to a temp probe at rev G. It also requires a different Power Interface Board. Looks to me they are doing a little more sophisticated control and sensing so that may be why you can't just bypass the sensor. It most likely requires a range of resistance that corresponds to an operating temperature range. These kinds of errors have happened in the past with Jxi and other brands. For the random fault, corrosion is often the problem. It only takes a minute amount and often you can't really see it. If it continues I'd clean the sensor connectors and spray with a good corrosion control product like Corrosion Block.

Does the Fenwal led light on top flash 3 times?

Chris
 
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Poolbreh

In The Industry
Jul 31, 2021
949
San Diego
I would check the ohms across the igniter. From other posts the igniters fail quite often. There should be a window in combustion chamber to watch the igniters glow. A bad igniter could be the result of bad heat transfer in the combustion chamber and goes with high flue sensor. Make sure the gpm are adequate for the heater.
 

rdf123

Member
May 29, 2017
13
Ancaster, Ontario Canada
OK. I changed the igniter and the heater ran for about 2-3 hours then the flue temp to high error came back. This time, I cleared the error and tried the heater again. As the unit started up, a puff of black smoke popped out the vent and i heard a snap from inside. I shut it down and restarted it. It would not light again. The new igniter i just installed was broken. I know enough not to touch it because of oil on your fingertips so I was quite careful when installing it. This does not say how careful the folks that packed it were. I am assuming it was contaminated before I put it in. I also realized I may not have tightened it enough in its socket. I was quite ginger with the nut pressure as i did not want to crack it. When i went to remove it, the nuts were quite loose feeling. I have ordered another igniter and a flue sensor. I will report back when they are installed.

Is there anything I might be missing? I don't want to go through another igniter if possible.
 

Poolbreh

In The Industry
Jul 31, 2021
949
San Diego
I would verify adequate flow to the best one can. With new igniter in I would monitor flame or take a video and we can see if someone sees something out of the ordinary. I don’t want another failed igniter either. But if it does fail I would be checking gas to see if it’s too rich. Let’s see if @swamprat69 or @JamesW have any wisdom to preach.
 

Poolbreh

In The Industry
Jul 31, 2021
949
San Diego
And the blower has been working consistently? I had jxi that had a flue sensor error and shortly after the blower failed. The air flow sensor should abrupt the flow of gas, but if delayed for a few seconds I would imagine could cause this.
 

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setsailsoon

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This is a new one on me. My guesses would be:
  • Bad connection at igniter contacts.
  • Loose connector nuts.
How many flashes do you get on the Fenwal?
 

rdf123

Member
May 29, 2017
13
Ancaster, Ontario Canada
I would check the ohms across the igniter. From other posts the igniters fail quite often. There should be a window in combustion chamber to watch the igniters glow. A bad igniter could be the result of bad heat transfer in the combustion chamber and goes with high flue sensor. Make sure the gpm are adequate for the heater.
I see the window. I dont know how you would be able to see the igniter coil from it. I cant see anything thru it at all.
 

Poolbreh

In The Industry
Jul 31, 2021
949
San Diego
I read this thinking it failed again but realized it snapped in half during shipping? I don’t think the flue sensor is bad but there is a good possibility there is a combustion issue triggering the flue sensor.
 

rdf123

Member
May 29, 2017
13
Ancaster, Ontario Canada
Latest news...My flue sensor arrived and I was going to install it along with my new igniter coil. I have been running the pump to keep the water moving over the last few weeks. My combustion chamber is full of water now. I think I had a leak and wondering if it may have been steam setting the flue sensor off? After the heater errored out, the pump still ran and filled the combustion chamber full of water and that is what blew my second igniter coil. Does this sound feasible? Is there any coming back from this. I spoke to one guy today who said the replacement combustion chamber is 2k with labor. Not sure how accurate that number is, I haven't done any research on it.
 

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