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Flue sizing

Jim Davis_3
Jim Davis_3 Member Posts: 578
in THE MAIN WALL
Your chimney size is just fine. Make sure that your pro takes a draft test and a combustion test. Drafthoods are designed to prevent appliances from venting and it sounds like yours is working. Unfortunately this is not a safe condition. Do not be misled into thinking the chimney is causing the problem in any way or that it needs to be lined. The safest distant of a drafthood from an appliance is the garbage dump.

Comments

  • David Hohengasser
    David Hohengasser Member Posts: 52
    Flue sizing

    I had a post a few days ago regarding orange gas flame. I have a professional coming next Tuesday. I am wondering if my flue sizing is correct, or acceptable. Lined chimney is 8 x 12. 10" round comes out of chimney for 36". Fed into this is the 7" gas boiler (187,000 BTU). Coming into the side of the 10" is a 5" that picks up two gas water heaters. They also have poor flames, but these have massive yellow tips. I do have a CO detector within 4 feet of all units. Is this sizing acceptable? Is there a minimum dimension the draft hood needs to be located off the top of the boiler? Mine is 16". H.B. Smith boiler manual does not indicate. I would like to know if the flue may be a cause of the problem before the pro arrives. I checked chimney with a mirror and it is clear. Thanks for any input.
  • David Hohengasser
    David Hohengasser Member Posts: 52
    Remove draft hood?

    Jim, are you saying I should remove the draft hood? Sounds like you are indicating there is not enough draft over the flame because it is pulling air through the draft hood. I thought the draft hood was to keep the pilot from going out when there is a down draft? I have a motorized flue damper after the draft hood so that should keep that from happening when boiler is off because it is closed. When on, the rising flue gasses should keep a down draft from happening. Is this correct?
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