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  1. #1
    Join Date
    Nov 2004
    Location
    West Newton, Pa.
    Posts
    915

    Default How do I minimize creosote buildup?

    I've noticed a lot of creosote buildup in the chimney of my new wood furnace. How do I keep this buildup under control? I've already had to let the fire die out so that I could take the pipe off of the back of the furnace and clean it out.

    I already burn one of the creosote cleaning sticks in the furnace every week but it doesn't seem to do much good. When I cleaned the flue pipe and chimney out I removed about one 5 gallon bucket of creosote out of them.

    I'm burnig hardwood (oak, maple, locust and cherry) that has aged at least 9 months after splitting. Help!
    Be Yourself, Everyone Else Is Taken!

  2. #2
    Join Date
    Mar 2006
    Location
    Wausau Wi
    Posts
    311

    Default

    nine months may not be long enough for the wood to completely dry. I notice creosote when burning green wood or softwoods. The other thing that causes it is if your furnace is starving the fire of oxygen, causing it to smoke a lot. Smoke makes creosote, so by burning a hot fire with very minimal smoke should solve the problem. One other thing, if the smoke cools off too much on the way out say on a large chimney with not much draw, that may do it too. I don't think thats your problem. Ok so lets see what others say, but that is my two cents. use it however you will. Hope it helps somehow !!
    Everything happens for a reason. Time heals all wounds - time and a half heals them even faster

  3. #3
    Join Date
    Jun 2006
    Location
    Oxford, Kansas
    Posts
    1,988

    Default

    I would say focus on bees pretty much nailed it. Your fire is not hot enough. Burning green and or wet wood. Heres how I run a fire I open up the damper and let it have air when starting out. After I have a good bed of hot coals add wood close the damper and shut the air down. If your stove doesnt have good draw you will have all kinds of problems. You should have very little smoke coming out the chimney at any time. I burn mostly hedge, locust, and hackberry I like for the wood to cure at least a year before I burn it. We try not to cut live trees unless someone is clearing a hedge row then we cut split and let set at least a year or 2 before we use it. I have an area I store the wood in to keep it dry from the weather. Be careful creasote is the ticket to chimmney fires

  4. #4
    Join Date
    Jun 2006
    Location
    Terre Haute, Indiana
    Posts
    238

    Default

    It could be the wood, the damper location, the amount of draw on the chimney, how you use the stove, many many things can be involved.
    Start working down the list and good luck.
    Also a sweep doesn't worry about real fire danger if the creosote is less than 1/4 inch deep along the chimney.

  5. #5
    Join Date
    May 2007
    Location
    Pocahontas County, West Virginia, USA
    Posts
    216

    Default

    A good hot fire a couple times a week should help keep the buildup burned off. Airtights running a bit too cool are usually guilty. We use box heaters here so I don't know how the thermostatic controls are bypassed to allow it in your situation.
    "Giving money and power to government is like giving whiskey and car keys to teenage boys." - P.J. O'Rourke

  6. #6
    Join Date
    Jul 2007
    Location
    Geneva,Florida, Seminole USA
    Posts
    290

    Default

    I picked up some oyster shells for my wifes chickens. On the bag ,I noticed instructions for burning in a wood stove to remove cresote. I was surprised, I'd never heard of this method, you might want to look into it.

  7. #7
    Join Date
    Apr 2006
    Location
    Indian Valley, Virginia
    Posts
    587

    Default

    a lot of furnaces have a thermostatic damper control. when the air flow is cut off the smoke is not hot enough to exit the chimney without condensing on the chimney walls which have become colder because the fire is so low. so try running your furnace wide open or not at all. just stop adding wood if it gets too hot. i think your firewood is fine since it has been sitting outside all summer. also, don't leave your furnace unattended. if power goes off then the furnace will over heat, unless you have an automatic backup generator.

  8. #8
    Join Date
    May 2005
    Location
    Whitefield, Maine USA
    Posts
    6,625

    Default

    Try to run a hotter fire. This sends more heat up the chimney and pulls more air into the stove to help combust the unburned gasses that otherwise would condense in your cold chimney. Creosote is in effect condensed smoke. If you keep the fire running hot enough, creosote won't be able to form. There's likely nothing wrong with your wood, though oak can use more than 9 months to dry out but if you're mixing it with drier wood it should be fine. The only problem with burning green wood is a lot of the heat goes to boiling off water and this cools the fire, and hence the chimney. With a cooler fire you get more smoke, which of course condenses in your cooler chimney.

    I never had a creosote problem until a couple of years ago when my wife and I were both working- we'd stoke up the stove and shut it back for the day- perfect conditions for making smoke. To combat the creosote buildup, we crank up a really HOT fire for about an hour first thing in the morning to get the chimney good and warm. Then we shut it back for the day. In the evening we again let 'er rip for a while. The creosote that does build up "cooks" into ash and falls to the bottom of the chimney where we clean it out periodically.

    George-
    Dulcius ex asperis

  9. #9
    Join Date
    Aug 2002
    Location
    Nehawka, Nebraska USA
    Posts
    43,654

    Default

    >A good hot fire a couple times a week should help keep the buildup burned off.

    Exactly. But keep up on it or you may have a chimney fire.
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 40y 200h 37yTF

  10. #10
    Join Date
    Nov 2004
    Location
    Brown County, IN
    Posts
    2,025

    Default

    Quote Originally Posted by George Fergusson View Post
    To combat the creosote buildup, we crank up a really HOT fire for about an hour first thing in the morning to get the chimney good and warm. Then we shut it back for the day. In the evening we again let 'er rip for a while.
    That's what I do, too. Once a day I load it up, open the vents all the way and let it burn really HOT for at least an hour. That burns off all the gunk that built up overnight when it was turned way down.

  11. #11
    Join Date
    Nov 2004
    Location
    West Newton, Pa.
    Posts
    915

    Default Thanks everyone

    I appreciate all of the responses. I guess I've got two circumstances that are contributing to my problem. The first is that this is our first year with our wood furnace and we didn't commit to having one until the early spring. Therefor, the wood that we are burning didn't have quite enough time to dry properly before we started burning it. I started cutting the wood in the spring of '07 from trees that were felled in February.I'm now cutting trees that i plan to split and use for next winter.

    The second problem that we have is that my wife and I both hold down full time jobs. Before I leave in the morning I load up the furnace with enough wood to keep the fire burning through the day. I then close down the draft so the wood doesn't all burn up before we get home. When I get home in the evening I normally throw some wood on the fire to get it burning well enough to heat the place to a comfortable temperature until we are ready for bed. Before bed I again load up the furnace with wood and close down the draft to a minimum to prevent the wood from all burning up before we get up in the morning.

    I guess what I will do from now on is open up the draft in the morning to get the furnace hot before I go to work before I load it up with wood and close down the draft for the daytime hours. After I get hoome at night I'll fire it up good and hot again for an hour or so to get the chimney cooked out before we head for bed.

    One more question. Do any of the products that claim to clean the creosote out of the chimney really work?

    Dale, I will look into the oyster shells as a possible creosote remover, thanks.
    Be Yourself, Everyone Else Is Taken!

  12. #12
    Join Date
    Oct 2000
    Location
    canada, New Brunswick
    Posts
    88

    Default cresote problem

    I worked as a chimney sweep for 20 years. Till my balance started failing me. you have received a lot of good advice here.. Only thing i would add is to invest in a automatic draft setup. Very hard to prevent cresote with manual draft. Some people can do this but as I have seen they tend to the fire through the day. The two main causes of cresote wet wood and poor burning fires.
    Bob F Seaman

  13. #13
    Join Date
    Nov 2004
    Location
    West Newton, Pa.
    Posts
    915

    Default automatic draft

    bobbb,

    I have an automatic draft in the vertical part of the flue between the furnace and the chimney. When installing it, I plumbed the flue in both vertical directions and adjusted the damper to 0.02 in. w.g. as indicated in the instructions (at least that's what the slide scale on the counterweight says that it's set at). I thought that this setting was too low but I've left it at this position for lack of experience in the matter.
    Be Yourself, Everyone Else Is Taken!

  14. #14
    Join Date
    Apr 2005
    Location
    Worthington, Pennsylvania USA
    Posts
    1,848

    Default

    The chimney fire situation is one you definately want to avoid.
    You do not state what type chimney the wood stove is hooked up to. Perchance it is an old chimney I would most definately insert a six inch daimeter stainless steel liner for protection.
    You have the right idea cutting firewood a year in advance, that saves a lot of creosote formation.
    Locust, ash and cherry as well as the oaks seemed to do best for us.
    I would definately get a creosote cleaning brush to clean the chimney regularly.
    "Younz" have a great day, I will.

  15. #15
    Join Date
    Nov 2004
    Location
    West Newton, Pa.
    Posts
    915

    Default Chimney liner

    pn,

    The chimney is I believe as old as that part of the house (1940's). However, I just had an insulated 7" stainless steel liner installed in September and had the outside bricks re-pointed. I used 7" to match the exhaust of the furnace.
    Be Yourself, Everyone Else Is Taken!

  16. #16
    Join Date
    Oct 2000
    Location
    canada, New Brunswick
    Posts
    88

    Default

    from my experince found these types of drafts do not work on wood stoves very well. these were mostly used on oil furnaces as I,ve seen. Also all these cresote preventers I have no use for. They are all designed to make a hot fire. A old newspaper crumpled up does the same thing. A lot of remedies are old wifes tales. In my area a lot of my old customers swore by potatoe peelings. You are on the right track first step dry dry wood. Also no such thing as wood to dry.
    Bob F Seaman

  17. #17
    Join Date
    May 2007
    Location
    Hillsboro, Wisconsin, USA
    Posts
    1,672

    Default

    Most every reply here is on-mark - you are burning wet wood, and don't have a hot fire. I cringed when I read that you pulled out five gallons of gooey creosote.

    I couldn't or wouldn't leave for work with an unattended fire going with that type of buildup. I hope you have good homeowners insurance. I am saying this because I have just witnessed first-hand the results of a home fire. My daughter and her husband returned home two days ago to their home on fire. Extensive fire, smoke and water damage. Unfortunately, many of their pets perished in the fire - the purebred puppy we gave them as a wedding gift, five (expensive!) tropical birds, three cats. Thank God they weren't sleeping or at home when the fire broke out. It was an electrical fire, but a wood stove with chimney buildup is a ticking time bomb.

    I work out of my home, so I can manage my wood stove properly. I crank the stove up to operating temperatures in the morning, maintain a moderate temperature during the day, and only at night after I have a HOT fire going do I load up the firebox, get the wood mass going again, and then and only then close the damper very low for the night.

    Due to proper burning and dry wood, my chimney scales off only flakes of very thin carbon - sort of like a shale consistency, which drops off in the off season and during chimney brushing prior to the next heating season.

    Please be careful.


    MM

  18. #18
    Join Date
    Mar 2005
    Location
    Erin, NY /Florence SC
    Posts
    3,361

    Default

    Like Bobb, I ran a chimney sweep business (in Denver in the 1970's), I kept my balance but didn't wear a respirator which caused me some problems (other than being young and stupid.)

    Creosote is the unburned hydrocarbons from the wood that condense on the chiminey lining when it is cool. Some pretty good advice from everyone here. I would focus on wood that is seasoned at least 1 year (especially oak, I've seen red oak wet a year after being cut). Beech and Ash dry quicker if you need to shorten the time to 8 or nine months. The more moisture in the wood, the more condensation. Running a hot fire at startup is a big one and a draft control should help quite a bit. I don't know if Corning still make catalytic converters for wood stove chimineys but if so this would be a good investment as well and would increase your burning efficiency by burning the unburned hydrocarbons causing the problems.

    Keep in mind that many of the products used to cut creosote are salt based and will degrade the metal in the stove and the chimney with extended use so use them only as needed.

    We always advised not to use carboard or any other paper product with Glue to start fires.

  19. #19
    Join Date
    Nov 2004
    Location
    West Newton, Pa.
    Posts
    915

    Default

    I've been thinking about this problem again recently and I have made an observation concerning the automatic draft. There is little or no creosote buildup between the furnace and the automatic draft, however the biggest buildup of creosote is immediately after the automatic draft. When I fire up the wood furnace and close the door the automatic draft immediately opens and lets air into the flue.

    Could it be that the incoming air through the automatic draft is cool enough to cool down the smoke coming out of the firebox enough that the creosote is deposited onto the inside of the flue pipe? I've thought of covering the automatic draft with aluminum foil to see what kind of effect this would have on the creosote buildup inside the pipe. I realize that this would increase the draft through the firebox and I would need to close the draft down to compensate the increased draft. I'm hoping that this would decrease some of the creosote buildup inside the pipe and allow more of it to exit through the chimney.

    Any thoughts or experience with this?

    Is an automatic draft on a wood furnace really necessary?
    Be Yourself, Everyone Else Is Taken!

  20. #20
    Join Date
    Jun 2006
    Location
    Oxford, Kansas
    Posts
    1,988

    Default

    I dont run one on mine. I guess it would depend on how high your flue pipe is. I am only going one story and through the attic. It does look like you are on the right track. If cool air is being introduced into the flue. It has to be cooling things down.

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