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Pilot adjustment on a Laars JX75- flame current readout odd

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spudwrench2
spudwrench2 Member Posts: 22
in THE MAIN WALL
I just installed a Laars JX75. (Natural gas version.) Per the manual, I decided to adjust the pilot using the "flame current" readout on the digital dashboard. Out of the box, the dashboard was showing something like 4.3 micro amps. Laars calls for a spec of 1.0 to 1.8 . I adjusted the pilot screw down on the gas valve to bring the reading to the top of the spec range (1.8.) Subsequently, the boiler would spark, light the pilot but not fire the main burners. It would repeatedly re-spark and start counting down. Presumably it would have eventually gone into lockout if I kept letting it retry long enough.
I experimented and it really wants to see a flame current of more than about 4 micro amps to light off reliably. Am I doing something wrong with my adjustment procedure? Is there any harm in leaving it set higher? Is there an issue with the boiler that goes beyond adjustment ? Thanks in advance!

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,834
    edited October 2022
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    Pilot needs to be large enough to light the man burner. Apply common sense here. I believe that micro amp spec is for a minimum current to sense a flame. Higher is OK. As the flame rod gets some buildup on it, the micro amp current will reduce. Cleaning the flame rod once a year will increase the current. Eventually that flame rod may fail. If that happens, you can replace it.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    spudwrench2
  • spudwrench2
    spudwrench2 Member Posts: 22
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    Thanks, Ed. I guess what's throwing me is the mfg specifying a specific range, if they said "1 micro amp or higher" I wouldn't give needing to set it to 4 to make it work a second thought. But having a top of the range sort of implies that the manufacturer thinks that there's some reason you don't want it above a certain value and/or that's there's something wrong with the boiler if it needs to be "misadjusted" to work. Having said that, it's totally possible that I'm just overthinking things and I should just be happy that it's working, shrug and walk away. :-)
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,523
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    I would not be concerned with a high reading. most of the time they are too low
    spudwrench2
  • spudwrench2
    spudwrench2 Member Posts: 22
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    OK, hearing the same from two pros is good enough for me, I'm going to let it ride unless I notice some actual symptoms. Thanks again to both of you for taking the time to reply!

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