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Thread: manometer accuracy

  1. #1

    Default manometer accuracy

    What is a good reasonable priced accurate manometer to measure my barometric damper?

    My furnace should be 0.025 and my flue should be -0.02. Looking at the gauges for sale i see accuracy (read
    inaccuracy) ratings that would make readings in the range that I need almost useless. Exp:

    0.3% of full scale 55.00wc (0.003x55=0.165) Does that mean that a reading of 0.02 could be off by as much as

    0.165?

    +/-0.3% of full scale 83.02 InH2O NKTECH NK-L3 (0.003x83.02=0.249)

    1.5% of full scale 4.00wc Dwyer 478A-0 (0.15x4=0.6)

    Am I doing something wrong here?


    tks,
    pa

  2. #2
    Join Date
    Dec 2003
    Location
    Kent, WA
    Posts
    8,582

    Default

    I don't know how you accurately measure like that. I have one that I think is 2" WC full range. You can read it to .1" OK. To get to .05 is difficult and to .02 would be impossible. Even if you could read it, I've found that most air sources pulse so the ball isn't sitting on one spot anyway. You can try to average with your eyes, but the pulses are not all the same.

    If you have a differential gauge (instead of measuring relative to ambient you put one side on combustion and the other side in the flue), that makes what you're trying to measure the difference of those two numbers which is .045". That's a bit easier to read, and error gets cut in half, but it is still difficult with the cheap consumer gauges I've seen.
    Mark
    Kent, WA

  3. #3

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