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Thread: is it AC or DC?

  1. #1
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    is it AC or DC?

    i have not been able to find whether flame rectification signals are measured in AC or DC. i am able to measure both and i have been writing both down in my inspection reports, but i would like to know for sure. i have only been able to find it listed in furnace literature as microamps...not which type.

    any insight?

    thanks!
    "Mother" is the name for God on the lips and hearts of children....The Crow

  2. #2
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    Good question Jay. My answer is DC. Reason being: We know the voltage SOURCE is AC voltage. A rod with lets say, 70, 80 or 110 volts AC. It is hanging out there and when the flame hits it , the jump is RECTIFIED, meaning actually changed from one (AC) to the other (DC) Others may have a better answer

    r404a

  3. #3
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    i just did a trane 80% and it had 2.64 uA DC and 5.53 uA AC. i do not remember what was required and i do not do enough residential to see where one type of microamps is way off and all is still good. the largest difference that i have seen was about 4-5 microamps between the 2 types...i think it was AC amps that was the largest...can't remember for sure.

    thanks!
    "Mother" is the name for God on the lips and hearts of children....The Crow

  4. #4
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    You put flame rectification numbers down, wow, are you new.

  5. #5
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    It's uA DC that you want. Been a long time, But if I had to guess, A steady 1.5 microamps or greater is what you want?
    It's All Good!!!

  6. #6
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    Quote Originally Posted by acjourneyman View Post
    You put flame rectification numbers down, wow, are you new.
    not new...just thorough. like everything else, things change overtime and i like to track them. but i like to track what is relevant too.

    good luck.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  7. #7
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    DC is the one.

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    A metal rod is sophisticated, I understand.
    It's All Good!!!

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    It`s better to be silent and thought the fool; than speak and remove all doubt.

  10. #10
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    Jay, the important question....did you make any money on the side job? Or was it a charity event? Amazing how large your family grows when folk's junk is broken. I got cousins I never heard of....

  11. #11
    The AC current is rectified through the flame and becomes DC

  12. #12
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    Quote Originally Posted by jayguy View Post
    i have not been able to find whether flame rectification signals are measured in AC or DC. i am able to measure both and i have been writing both down in my inspection reports, but i would like to know for sure. i have only been able to find it listed in furnace literature as microamps...not which type.

    any insight?

    thanks!
    The microamps that are important are DC.

    The applied signal is AC, and the portion that conducts via the flame is the DC component. That's the voltage component the module looks for, and it's what we test for. The AC is still there, continuously supplying that portion of the AC cycle that moves in one direction via the flame.

    To be precise, the flame allows micoamps of pulsating DC. The module has board components to smooth out the signal a little to make it usable, usually capacitors.

    To get really smooth DC, you would need a full wave rectifier and electrolytic capacitors. The flame is merely acting as a diode, and that is a form of half-wave rectification.
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  13. #13
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    Quote Originally Posted by timebuilder View Post
    The microamps that are important are DC.

    The applied signal is AC, and the portion that conducts via the flame is the DC component. That's the voltage component the module looks for, and it's what we test for. The AC is still there, continuously supplying that portion of the AC cycle that moves in one direction via the flame.

    To be precise, the flame allows micoamps of pulsating DC. The module has board components to smooth out the signal a little to make it usable, usually capacitors.

    To get really smooth DC, you would need a full wave rectifier and electrolytic capacitors. The flame is merely acting as a diode, and that is a form of half-wave rectification.
    half-wave rectification...exactly!!...not AC and not DC. i was pretty sure it was DC but nothing was officially listed.


    Quote Originally Posted by jimbob73 View Post
    A metal rod is sophisticated, I understand.
    just like checking/tracking milliamps on pilot burners for flame degradation...it doesn't take long to write down.


    Quote Originally Posted by lipsoffurry View Post
    Jay, the important question....did you make any money on the side job?....
    not much.


    Quote Originally Posted by lipsoffurry View Post
    ...Amazing how large your family grows when folk's junk is broken...
    you got that right!!



    good luck.
    "Mother" is the name for God on the lips and hearts of children....The Crow

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