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-   -   Gas pressure adjustment for high and low fire, (https://www.askmehelpdesk.com/showthread.php?t=597963)

  • Sep 19, 2011, 11:08 AM
    rockets222
    Gas pressure adjustment for high and low fire,
    Goodman 95% 2 stage furnace converted to lp. Cannot adjust manifold pressure for low fire or high fire are the springs for the lp conversion the same? How can I adjust the pressurtes
  • Sep 19, 2011, 03:18 PM
    mygirlsdad77
    Lp conversion requires two new springs, and new orifaces on the goodman 95% two stage units. The conversion kit should have come with new springs (same size, and usually silver vs white for nat gas.) Does your unit have a honeywell, or white rodgers gas valve? Does the unit ignite at all? Let me know more here and I will try to help.
  • Sep 19, 2011, 04:11 PM
    rockets222
    The unit has a honeywell gas valve. I did ghange the burner orifaces (3) and the (2) springs supplied in the conversion kit. Incomming gas pressure 11.5-12" of water collum. the furnace ignites fine (not rough) cycles great with the thermostate. book said to set (low fire/1st stage) to 6.0" of water collum.then (high fire /2nd stage ) to 10.0" of water collum. i go to set the low fire spring settin(turned screw both clockwise and counter clockwise and seen no movement on the monometer(pressure reading) it is at about 7" wanted to adjust to 6.0". i thought ok lets see what the high stage (2nd)stage does could not get it above 7.0" no matter how I turn the screw. This is what maade me think are the springs for a particular port low or high. Flame looks great nice and blue(not yellow)
  • Sep 20, 2011, 04:37 PM
    mygirlsdad77
    Okay. Here's the thing. The conversion manual is a little decieving, or hard to understand. Easy to confuse 1st stage with 2nd stage. Actually, 1st stage is high fire. 2nd stage is low fire. So you may have been turning the wrong screw. Common mistake. It really doesn't matter if you set 1st or 2nd stage first with a honeywell. It does with the white rodgeres, but you don't have that, so lets start from the beginning.

    Your control board had three dip switches, yes? Make sure the one in the middle is set to 1 stage, just for starting. Then once the burner ignites, adjust the high side port till you get 10 inches water, or as high as you can get it. Many times you will only get up to 9 or so. But that's okay, as the goodman manual allows a little give. Once you have your high adjusted, switch the middle dip switch over to 2 stage, and fire the furnace. You will have to wait a couple seconds, as the furnace always fires in high fire, then goes to low fire (second stage). Once you see the flame lower (or see it on the monometer) adjust the low port till you hit six.. Should be all set after this, although it never hurts to run through this sequence a couple of times just to double check both pressures. If you absolutely can't get the pressures within range, you either have an obstruction in the gas line, a fualty gas valve, or bad springs in the conversion kit. One way to to tell if you have an obstruction, or lack of gas flow on the inlet side, is to fire the furnace with your monometer on the inlet side of valve and see if you are still in the 11 to 13 range. Try all of this and let me know what you find. Good luck.
  • Sep 23, 2011, 04:17 AM
    rockets222
    Your advice was right on the money.followed your instructions and it worked just the way you said it would. Gas pressures dialed right in. you were right the manuel doesn't tell some of the most important details.thanks greatly for the info

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