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White and Black Flakes/Debris Outside of Furnace

JaeSue Member Posts: 5
I purchased a name-brand oil furnace two years ago. It replaced a workhorse 48 year old furnace which rarely needed attention, mainly the yearly maintenance. During these two years of using the new furnace, I have noticed a build-up of white and black particles on the furnace ledge, the burner box, and the floor. The techs from the heating co. have come out repeatedly. A setting was adjusted and a year later returned to its normal setting. A year ago I was advised to buy a new chimney liner which I did. The flue pipe has been replaced several times. When it was replaced in September, I could see it filled with "crud." It had previously been replaced 9 mos. earlier. It was replaced again a few weeks ago. Most recently two furnace techs told me that what I am seeing is "normal." They called it "condensation." (I thought condensation was water. These particles are similar to salt and pepper.) I have been continuously vacuuming the particles. The problem has been on-going for two years.

The most recent advice given to me was to just make sure I have the furnace cleaned every year (Yep-been doing that for years) and to "give it time."

Could someone explain what is really happening and what can I say to the techs to get this fixed.

Thank you for your help.


    HVACNUT Member Posts: 5,247
    Can you name the manufacturer of the furnace, (or is it a water boiler?) and burner?
    Maybe post a pic or two standing back some to show a full view. And of the particles.
    The flue gases should NOT be condensing, especially with a chimney liner.
    Seems like improper burner adjustments.
  • HomerJSmith
    HomerJSmith Member Posts: 2,266
    edited October 2018
    Pics would help. Your furnace (boiler?) isn't in a laundry room is it or near any stored chemicals? Acids or any chemicals that could be converted into acids in the combustion process?

    Normal flue products are acidic in the present of water. If your appliance is condensing, you could be destroying your flue in short order.

    If it is a boiler the return water to the boiler must be above 135 deg. to keep the boiler from condensing and sending the flue gases to the roof. An extremely cold flue pipe can also cause the flue gases to condense.

    Your combustion could be out of whack. That's a technical industry term.

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,236
    Yeah I vote for condensing also, maybe to low flue temp, under fired, etc.
  • JaeSue
    JaeSue Member Posts: 5
    It is a Carrier oil furnace, Riello burner. It is not a boiler. No water is involved.

    Thank you for the insights.
  • JaeSue
    JaeSue Member Posts: 5

    EBEBRATT-Ed Member Posts: 13,766
    You need a service technician who knows what they are doing. Have they ever done a combustion test of this unit. Did they drill a 1/4"-5/16 hole in the smoke pipe for testing?
    HVACNUT Member Posts: 5,247
    Even though the furnace is only 2 years old, call a reputable heating company to, first, test the heat exchanger.

    A newer furnace, Riello burner, and chimney liner, properly installed should never be in that condition.

    I would also have them check the chimney liner to make sure it's fully connected. Horizontal, in to a drop tee, then vertically up and out. Sealed crown, and sealed breach. Any rips or tears and it needs to be replaced.
    The low flue gas temps of the Riello might need all the help it can get for a warm chimney and proper draft.
  • JaeSue
    JaeSue Member Posts: 5
    It is a reputable heating co. that installed it. That is one reason I chose them. They have agreed to extend my service policy for one year. I appreciate your evaluations and am glad that I am not wrong in thinking that this is not "normal" as they have told me.
  • justHEATit
    justHEATit Member Posts: 17
    My guess is its ur combustion chamber falling apart and sucking up ur exhaust in the furnace and filling the flue.

  • JaeSue
    JaeSue Member Posts: 5
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,236
    Your combustion chamber isn't falling apart, despite what @justHEATit stated. That's not a statement any knowledgeable professional would make. So wipe it from your brain.

    For starters it needs a proper cleaning, proper firing rate, proper draft, and proper combustion set up.
    Do you have a copy of the last combustion report? Should've been a printout left on site. This will help with the problem solving.

    It's signs of condensing in the flue, from one or more of the things I stated.
  • SuperTech
    SuperTech Member Posts: 1,940
    Have your technician check that the oil pump pressure and nozzle match the manufacturers specifications. Then he should perform combustion analysis with a digital analyser and make sure it's burning clean, with low CO. Stack temperature of the flue is very important! I would expect at least 425-450 degrees minimum. If it's not getting there before it shuts off then that's the cause of the problem.

    Could it possibly be grossly oversized and short cycling? How long does your burner usually run before shutting off? Is the system Zoned?
  • captainco
    captainco Member Posts: 765
    Black is soot and white is dried condensation. There are many reputable companies that don't know what they are doing but they do it less than others, Everything stated is based on ignorance and old wives tales.