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Bethlehem boiler

The chimney is not blocked, and yes that is a plus .5 pressure. It did drop to a .35 when the cap was removed. Thanks again. Chris.

Comments

  • Chris R. Halcro
    Chris R. Halcro Member Posts: 3
    Bethleham boiler

    I have been trying to help a private school with a boiler problem. The boiler sounds like a double A fuel dragster while in operation. Has been this way since it was installed in the sixties, I guess. It is about 6,300,000 btu firing capacity by the name plate rating ( for fuel oil ), operating on Nat gas. The stack is 16 inches by about twenty feet tall. Back preesure at about 1 foot above breech is .5 inches on low fire. Changing air fuel mixture doesn`t help until theres almost no gas in the mixture. Is the stack way to small? Another one of my customers bought an almost identical boiler made in the 80's that has a 24 inch stack. Both are two pass boilers. Thanks, Chris.
  • john_35
    john_35 Member Posts: 29
    bethlehem

    Is that +0.5"WC? I don't mean to sound stupid but are you sure the chimney isn't blocked?
  • Earthfire
    Earthfire Member Posts: 543
    stack size

    I'd check the manufacturers specs. They usually have a vent sizing spec.
  • Ken D.
    Ken D. Member Posts: 836
    Bethlehem Boiler

    Do you have any exhaust fans operating that would cause poor venting? Do you have enough make up air? Is it possible you are over fired? Do you have good quality fuel? I had a situation where a building maintenance man would pour waste oil into tank. This increased the btu content of the oil resulting in poor combustion and draft. Also, a chimney too large (in diameter) or too short could also be a possibility.
  • Chris R. Halcro
    Chris R. Halcro Member Posts: 3
    Bethlehem Boiler

    This boiler is operating on gas only. If I slowly close the gas valve the rumbling will stop when its almost shut. At that point it's lost about 10 percent in efficiency and there is almost no flame.
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