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Need Chart for btu output versus gas pressure

HI,
We are constantly finding oversized steam boilers and we reduce the firing rate whenever possible to proper levels. However, I need a chart showing the btu capacity versus gas pressure for standard orifices. If 3.5 inches is 100% ( like on most atmospheric boilers), what percentage input can I expect at lower pressures. I know 0.8 inches is about 50% and 1.2 is about 60% ( from LGB boilers), but a full chart would be very useful. Thanks!
The Steam Whisperer (Formerly Boilerpro)

Chicago's Steam Heating Expert





Noisy Radiators are a Cry for Help

Comments

  • Zman
    Zman Member Posts: 6,966
    Does this help?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • j a_2
    j a_2 Member Posts: 1,796
    I would be interested in hearing about your results…I was not a fan of down firing…For several reasons….
  • I am looking for a chart that goes below 3.5 inch, probably down to about 0.8.

    We have had excellent results with down firing on steam systems (steam is about the only systems we work on). Often times, noise disappears or is greatly reduced, the effect of incorrect near boiler piping are reduced, heat is more even and fuel usage drops. I suspect is also greatly reduces stress on the equipment and system by reducing thermal cycling. On power burners, we usually pick up firing efficiency, with atmospheric we usually lose a few points. It also often allows the use of smaller gas meters, so monthly charges can be reduced greatly. Our down firing typically is simply getting the input to the proper rate that should have been installed in the first place. have to watch the chimney, though. I may be seeing some condensing going on in a 2000mbh input atmospheric WM LGB that is now allowed to operate hi / low as needed.
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert





    Noisy Radiators are a Cry for Help
  • Abracadabra
    Abracadabra Member Posts: 1,948

    I am looking for a chart that goes below 3.5 inch, probably down to about 0.8.

    We have had excellent results with down firing on steam systems (steam is about the only systems we work on). Often times, noise disappears or is greatly reduced, the effect of incorrect near boiler piping are reduced, heat is more even and fuel usage drops. I suspect is also greatly reduces stress on the equipment and system by reducing thermal cycling. On power burners, we usually pick up firing efficiency, with atmospheric we usually lose a few points. It also often allows the use of smaller gas meters, so monthly charges can be reduced greatly. Our down firing typically is simply getting the input to the proper rate that should have been installed in the first place. have to watch the chimney, though. I may be seeing some condensing going on in a 2000mbh input atmospheric WM LGB that is now allowed to operate hi / low as needed.

    Where do you find various sized replacement orfices for the LGBs? Or do you just drill your own?
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    Dave - I have a calculator that will do all that for you. I am very busy but when I have time I will send you the info so you can order it.
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    Dave, by the way we are going to get a chance to look at the new conversion burner I have been consulting on. We will be firing it tomorrow at my training center. I wish you could have been with us to see it .
  • BobC
    BobC Member Posts: 5,228
    Tim, when will this new conversion burner be unveiled to us?

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Thanks, Tim.

    Been too busy to take on anything else. I expect to be installing a LNB 1000 soon with full outdoor reset for steam on a Peerless LC-07 in a system that I orificed and runs with a vacuum pump.

    I don't resize the orifices, just decrease the manifold pressure. The LGB can be set up 2 stage with just the factory gas train ( except the 2 smallest models). High fire is 3.5 inches, low is 0.8 (older models) 1.2 (newer models)
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert





    Noisy Radiators are a Cry for Help
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    New burner possibly in limited numbers in the late spring or early summer.