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    Flame impingement (6 Posts)

  • Gordan Gordan @ 11:03 AM
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    Flame impingement

    Flame impingement on a cold surface can lead to incomplete combustion, meaning soot and CO. Yet... all gas stoves I know have some degree of flame impingement. I tested my gas burners over the weekend and got some interesting results... I have a big honkin' center burner that I figured would produce the most CO but it actually barely had any, whereas some of the smaller ones had in the range of 100 ppm. And this is for an unvented appliance (range hood notwithstanding.) This was without a pot filled with cold water on top; I'm sure things would be worse with, so I'm almost afraid to test. There's no way to alter the fuel-air mix on these except the big honkin' one.

    Ah, well... should have gotten an induction stove, but I likes the flame. Anyone else take a combustion analyzer to their stove or other common appliance?
  • unclejohn unclejohn @ 2:11 PM
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    Sounds like

    Your slower then I am and I'm at dead stop.
  • Gordan Gordan @ 3:39 PM
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    Hm

    I blame daylight savings, and possibly breathing too much CO. Just kidding on this last one.

    Yeah, re-reading what I wrote, it does seem a bit rambling. Just musings about how much care we take (well, some of us, anyway) to properly tune the combustion on an appliance that exhausts to outside, when there are all these other potential sources of carbon monoxide that just dump it into the indoor air.
  • Steamhead Steamhead @ 4:20 PM
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    I do that frequently

    if the stove burners have hooded (adjustable) orifices, you can adjust the flame height by turning them down.

    I always test with a pan of cold water on the top burners since that lets me see how they perform under actual working conditions.

    With ovens, you want to keep the flame from hitting the "flame spreader" as much as you can. One way to do this is to open the air shutter all the way, assuming this doesn't cause the flames to lift off the burners. This shifts the air supply to more primary air and less secondary air, which shortens the length of the flame. Many oven burners also have hooded orifices as well.

    In some cases, the oven will need to be cleaned before you can get acceptable CO-air free readings.

    Tim McElwain has a very good training manual on these.
    "Reducing our country's energy consumption, one system at a time"

    Steam, Vapor & Hot-Water Heating Specialists

    Oil & Gas Burner Service

    Baltimore, MD (USA) and consulting anywhere.
    This post was edited by an admin on March 11, 2013 4:21 PM.
  • Tim McElwain Tim McElwain @ 9:31 PM
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    Combustion testing should be done on all

    fossil fuel burning appliances in the customers home. If you don't and something happens you are liable.When you consider that the ANSI standards for gas ranges allow 800 PPM on an oven that is insanity. Properly set up the gas oven should be less than 25 PPM and no impingement. Impingement will often in addition to CO  (colorless, odorless and not detectable by human senses) produce aldehyde a pungent almost kerosene type odor. That is a clear indication of CO being present. I have a complete protocol for use on gas ranges and how to test and set up safely. Actually I would like to see a mandate for a range hood on all domestic gas ranges.
  • Steamhead Steamhead @ 11:52 PM
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    Tim's quote

    "When you consider that the ANSI standards for gas ranges allow 800 PPM on an oven that is insanity"

    is spot on. When I first tested my oven, it was over 1100 PPM air-free. Some simple adjustments cured this.

    And this was on a stove that was installed around 1968.

    Let us know how you make out.
    "Reducing our country's energy consumption, one system at a time"

    Steam, Vapor & Hot-Water Heating Specialists

    Oil & Gas Burner Service

    Baltimore, MD (USA) and consulting anywhere.
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