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Downdraft

BossmanBossman Member Posts: 11
edited November 29 in THE MAIN WALL
We bought a open concept 1920-1950 sq foot house. We have a gravity fed oil stove that gets a downdraft it seems on very windy fall/winter days. Can see smoke and smell unburned oil at its worst. The flue pipe looks to be high enough & have a cap, We also have a fire place separate from this heating source. Could this cause/add to the issue? The home is 20 years old. Seems well insulated. No exhaust for the gas stove and downstairs bathroom, that has exhaust vent, door is usually closed. No one knows anything or enough about the oil stove, nestor martin C100, I believe, in my area for whatever reason. Indiana county/Cambria county PA. If by chance there's someone reading that's near us. Suggestions welcome.

Comments

  • Jamie HallJamie Hall Member Posts: 11,435
    These are, unless I am mistaken, not fan assisted. As a result, they are vey sensitive to the draught -- and therefore the chimney construction and placement.

    You might try a really good chimney sweep to check the chimney and, perhaps, suggest ways of reducing or eliminating downdraught conditions.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ZmanZman Member Posts: 5,334
    Where is combustion air coming from?
    What else is trying to remove air from space?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HomerJSmithHomerJSmith Member Posts: 714
    You might try wind directional chimney cap.
    https://www.luxurymetals.com/wind_directional_caps.html
  • BossmanBossman Member Posts: 11
    > @Zman said:
    > Where is combustion air coming from?
    > What else is trying to remove air from space?

    Nothing else venting, windows/doors all seal tight. Only other exit is fireplace chimney damper shuts tight. It pulls inside air in from behind through the typical barometric door.
  • Jamie HallJamie Hall Member Posts: 11,435
    If this is a really tight house, it is possible that it simply isn't getting enough combustion air to draught properly under certain conditions.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • BossmanBossman Member Posts: 11
    > @Jamie Hall said:
    > If this is a really tight house, it is possible that it simply isn't getting enough combustion air to draught properly under certain conditions.

    How would I approach describing this to a service tech.? It burns great till the wind blows doesn't seem to be adequate and it isn't windy when I get anyone to come if they even show. Looking at the install manual everything appears correct and sufficient etc. There isnt much to adjust clean or maintain. Only other variable is its smack dab in the middle of lots of trees. Previous owner said their only issue was keeping the fuel from waxing due to the tank & filter being exposed outside. They've been helpful and honest with other questions so I doubt they would lie concerning this.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,103
    @Bassman
    The trees probably don't help. Is this an inside or outside chimney? I looked on there web site I guess they are made in Spain.

    I would start from the beginning. Call the MFG and talk with them. Give them size and type of chimney and height. Masonary chimney, metal chimney? etc. Also get a install manual read it and check for problems

    Also, the "C" series on there web site are all wood burning and I couldn't find a "C80"

    What type of oil are you burning?? I would think these could only burn kero or #1 oil
  • HomerJSmithHomerJSmith Member Posts: 714
    edited November 28
    If it works fine with no wind, it doesn't mean you have enough combustion air, but that's another problem. You have to have air coming in if you have air going out. Open a window and see what happens.
    Put your hand on the flue output to the boiler or use a laser thermometer is it really hot, if so you probably have enough thermo lift.
    I suspect down draft in the chimney. If it is an exterior chimney the cold could cool the exhaust gases and effect their buoyancy. The buoyancy may be marginal and a slight downdraft may kill it.
  • BossmanBossman Member Posts: 11
    > @HomerJSmith said:
    > If it works fine with no wind, it doesn't mean you have enough combustion air, but that's another problem. You have to have air coming in if you have air going out. Open a window and see what happens.
    > Put your hand on the flue output to the boiler or use a laser thermometer is it really hot, if so you probably have enough thermo lift.
    > I suspect down draft in the chimney. If it is an exterior chimney the cold could cool the exhaust gases and effect their buoyancy. The buoyancy may be marginal and a slight downdraft may kill it.

    Flue is 2/3 inside exits through ceiling (open concept cabin type house) another 1/3 exposed ouside roof. Instructions say open window till flue is warm when lighting. Flame builds slowly as oil trickles in on gravity. When warm/hot opening a widow doesnt change anything especially on the trouble days. First thing I tried. Draught door operates freely however I've never seen it operate like the usual gas or oil furnace/boiler I grew up with. Has anyone had success with the caps advertised to prevent downdraft? Vacu-Stack..
  • Jolly BodgerJolly Bodger Member Posts: 133
    Put a wind directional cap on it. When the wind blows it will make a little draft in the chimney. I think you have already tested to see if the house was negative by opening the window when you were having problems. If the house was going negative, opening the window should have fixed it. I suspect the wind and the trees makes a little high pressure zone around the chimney.
  • HomerJSmithHomerJSmith Member Posts: 714
    I have used wind directional caps on fireplaces with great success, but not on a boiler or furnace. But, I would certainly do it.
  • icy78icy78 Member Posts: 274
    Opening a window will not necessarily prove that you have enough combustion air it just may make it easier for the air that is in the house to leave the house, and still makeup that air back through the chimney. When the wind blows from one side of the house particularly if it's a leaky house, it can pressurize one side of the building and make a negative pressure on the other side of the building.
    If that is the situation for your heating Appliance it could downdraft through the chimney. ... if it's easier for the air to go that way.
    If the chimney is backdrafting when the appliance lights what will make it decide to updraft? It will not updraft Unless somehow it becomes easier for those flue gases to go up the chimney rather than into the house. The only way that that can happen is for the chimney to have a negative draft.
    There are ways of testing all this and proving what is needed. Also as others have said have the Integrity of the chimney checked but I actually mostly suspect you are probably venting out the attic and pulling in air through the chimney.
    Remember the flue is simply a duct between the building and outside and you have to make sure that the flue gases will go the right direction through that duct.
  • EdTheHeaterManEdTheHeaterMan Member Posts: 248
    edited November 30
    There are too many variables to solve your problem in this forum. Only a trained chimney professional or a HVAC or Plumber that has researched and understands combustion air, and venting. will be able to help you. Sometimes I go into a home and observe the chimney condition from the street at I approach. I can see a draft problem before I enter and know that the customer will have experienced problems with odor or soot in the burner room. Here are some of the things I look for. Your mention of the Trees is of interest to me!. They keep growing and the problem increases. When the trees were below the roof line years ago there may have not been a problem.
    Illustration is from Field Controls
  • EdTheHeaterManEdTheHeaterMan Member Posts: 248
    A picture of the outside of your home with the surroundings relative to the chimney might help. different angles
  • BossmanBossman Member Posts: 11
    Didn't even realize I could post images.
  • BossmanBossman Member Posts: 11
    Image 1
  • BossmanBossman Member Posts: 11
    Says I'm not allowed to upload files in this category!!??
  • Erin Holohan HaskellErin Holohan Haskell Member, Moderator, Administrator Posts: 1,172
    Hi @Bossman - I've moved this post to The Main Wall. Please try uploading your photo and let me know if you run into any issues. Thanks!
    President
    HeatingHelp.com
  • BossmanBossman Member Posts: 11
  • BossmanBossman Member Posts: 11
    Inside through ceiling/roof.
  • BossmanBossman Member Posts: 11
    Exiting ceiling/roofing
  • BossmanBossman Member Posts: 11
    Rear left of stove damper. Sorry for the delay weak signal and was spam blocking me
  • pecmsgpecmsg Member Posts: 963
    Bossman said:

    Exiting ceiling/roofing

    The top of that flue doesn't look higher then the roof 10' away.

    Perhaps one more section to elevate it!
  • STEVEusaPASTEVEusaPA Member Posts: 3,481
    The chimney should be 2.5 ft higher than anything within 10 feet.
    The other chimney, the tree and the slope of the steeply pitched roof are all working against you, as well as the large section of uninsulated flue pipe above the roof line probably cooling the flue gases.
    steve
  • pecmsgpecmsg Member Posts: 963
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,755
    I'd definatly add another section of class A chimney on top of that. You'll have to know what stand and size is already there and simply remove the cap, add new pipe, and install cap on that. Looks like you'll need a bucket truck or man lift.
    Serving Northern Maine HVAC, and Controls
  • gennadygennady Member Posts: 770
    edited December 8
    You have to have enough combustion air. Bring duct from outside into boiler room/ closet. You should install outside louver with not less than 1/4” mesh. 1 SI per 1200 btu boiler input is a size of the louver. Size duct properly. By insulation, sealing house you prevent air to infiltrate house and be used by boiler. Fireplace makes situation much worse.
    Gennady Tsakh



    Absolute Mechanical Co. Inc.

    www.AbsoluteMechanicalCoInc.com
  • Jamie HallJamie Hall Member Posts: 11,435
    Also -- you will need to brace that taller flue. Otherwise it will blow down, guaranteed.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • icy78icy78 Member Posts: 274
    IF, it's a flue issue, a Star-Kap could alleviate the issue, without extending the flue.
    See if its use is appropriate in your case.
    Field Controls Star-Kap
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