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additive to counteract chemicals in wood?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by woodmeister, Jan 14, 2009.

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  1. woodmeister

    woodmeister New Member

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    Spoke to someone today with a central boiler and he mentioned something he put in his boiler to counteract chemicals in the pallets he occasionally burns. Apparently someone he knew with the same unit burned a steady diet of pallets and the chemical reaction thinned the walls of the boiler to the point that when he scraped the creosote he punctured the unit, and the company wouldn't warranty the unit. I never considered burning pine but I have a line on a significant quantity of packing materal and am concerned if it is fact treated wood. The name of the stuff sounded like amistrol? Anyone ever heard of this?

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  2. jebatty

    jebatty Minister of Fire

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    No. And if for some reason the wood you want to burn has been chemically treated, don't burn it. Some say oak should not be the sole source of fuel due to high acid contact. Others have burned nearly 100% oak for years with no problem. I don't know.

    All wood (including pine) burns just fine if burned properly. Wet wood, smoldering fires, cool fireboxes (like in OWB's), condensation in the firebox or chimney, etc. are wood burning issues that can result in a number of problems.

    A principal problem is creosote, which is a natural result in many wood burning situations. Creosote iin contact with water or water vapor forms acid. Acid attacks steel with a vengeance, resulting in thin boiler walls, corrosion, holes, etc. The solution is burning well seasoned wood, minimizing smoldering fires, and keeping the firebox/chimney hot to prevent/minimize creosote formation and to not allow water condensation.

    A related issue is summer shutdown of a stove/boiler that has creosote in the firebox or chimney. Condensation over the summer from water vapor in the air reacting with the creosote present needs to be eliminated or minimized. The ideal would be to clean the chimney well after the heating season, scrape out as much of the creosote as reasonably possible from a firebox, and then seal the firebox to prevent water vapor from the air coming into contact with the firebox. An alternative or added protection would be to add a small heat source (light bulb) in the firebox to keep it warm so as to prevent condensation and eliminate the presence of any water.

    Many people do not take any precautions with regard to creosote, except maybe clean the chimney, and never have a corrosion problem. I don't want to overstate or understate the problem; only bring it to attention.
  3. slowzuki

    slowzuki Feeling the Heat

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    OWB's rotting out is not related to the species of wood burned or wood treatments.
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    My dad has put more than 10 years on a Heatmor OWB burning nothing but red oak, and it still holds water.

    That's the trouble with pallets--you don't know where they've been what they're made of, or what has been spilled on them. Plus, they're a real pain to cut up.

    That said, Central Boiler makes (or at least, made) an OWB with a door big enough to get a standard pallet through. Pretty slick, really--you just keep stacking pallets in and recover the btus. Probably not good for long burns (way too much air), but not a bad way to dispose of something that you'd probably have to pay to have hauled off, assuming of course that they don't contain toxic chemicals.
  5. rcollman

    rcollman Member

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    Ok, now I am worried again. I definitely have a creosote in my fire box. Especially around the door. I can heat up the small "ash rake" supplied by Tarm and push 1/4 deep of black stuff into the fire box off the flat surfaces every couple of weeks. The other flat surfaces in the firebox itself seem to be ash like and no shinny "black asphalt" visible.

    With the colder weather and more experience, I like to think there is less creosote due to idling. I am better able to time my burn (fuel load) given the prediction on the temp. I have also been making sure most of my wood meets the 4 inch circle test. But I don't have a moisture meter. Sigh.

    Should I start making a small but hot fire with the damper and lower door open? Should I be using some chemical at the same time?

    Storage is a ways off.

    Love this forum. -30 F (-34C) is in our forecast for the next two days. Suspect my Solo40 will keep on cooking.
  6. Tree farmer

    Tree farmer New Member

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    I end up with the same thing in the mouth of my loading chamber, I just scrape it into the coals every so often. The loading chamber walls seem to be in a steady state of a coating of creosote not much more than an 1/8" thick with some large flakes that form and eventually burn. I spray some rutland creosote reducer spray in once a week, not really sure it amounts to much. The Eko manual does say throw some potato skins in occasionally and I would imaging whole potato's would work as well. I believe it reduces the creosote maybe better than the commercial stuff.
  7. jebatty

    jebatty Minister of Fire

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    I'm going to cast a vote to ignore the creosote unless it actually is causing a problem, such as blocking the airways, preventing the damper from closing, or preventing a door from closing with a sufficient seal to prevent smoke from escaping., or finally building up in the firebox so much you can't get any wood in (well maybe a little less). The reason for this vote is that before my Tarm I had an OWB that, besides being a smoke dragon, built up huge gobs of creosote in the firebox. During the 10 year period I operated the OWB, nothing impaired the operation of the boiler. The creosote buildup looked ugly, but the gobs eventually would fall off the firebox into the fire, and the rest of the creosote would "self control" so as to never cause a problem. Creosote also would drip down the inside of the firebox door, but I always was able to close the door with a sufficient seal. I never did anything about the creosote.

    My Tarm creosote buildup is "minimal," meaning mostly shiny, black, flaky stuff. There is a little buildup on the flats around the firebox door opening, and I lightly scrape the loose stuff off into the firebox once in awhile. I burn dry wood and don't bother with a moisture meter because my wood has dried at least two full summers and consists of splits rarely larger than 5".

    Before you conclude the creosote is a problem, try to identify what the problem is before you seek to solve it. And the best course remains to burn dry wood.

    One other point. The Tarm manual recommends refueling only at low coals. Based on my experience, from a cold start and full fuel load, the boiler operates for a long time before it may reach idle temp. That long fire burns off virtually all the creosote causing compounds in the wood, and that fire is hot. If you wait until low coals before refueling, then the refuel will largely burn in the same manner.

    But, if you add fresh wood to, say, a 1/2 burned load, and the boiler already may have idled a couple of times and is up to temp, that fresh wood will burn very hot, quickly bring on another idle cycle, and then continue to throw off volatiles which will have nothing to do but condense inside the firebox, resulting in creosote. Although it may not work in every situation to get the heat you want, especially if you don't have storage, I suggest not adding fresh wood unless the boiler will burn that fresh wood for a good while before going into an idle cycle.
  8. rcollman

    rcollman Member

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    Thanks Jim,
    I think I am going to recommend to my significant other that we get a moisture meter (just for the data). I suspect that the wood should/could be drier.

    I hear you about the burn. With wetter wood and no 500 gals of storage, it is sort of understanding the furture BTU demand over time, the transfer rate from the boiler to the delta mass potential of "natural" storage (55 gals in the boiler, metal radiators, pipes and water in them). I don't mind when the fan cuts off and there are 3 or 4 now dried sticks in the box. It is when it cuts off and the fire box has wood to the middle of the door, with the wetter wood just steaming away :) Right?

    We went from 2 cords to 6 cords a year and our carry forward of 3 cords, about half was burned in our SunRay before the Solo40 was installed. I am still thinking the SunRay was 45% efficent based on need and the Solo is around 80% by comparison. Anyway you look at it we are behind the curve.

    Next spring, before mud season, we are looking for a small load of log length, and get another 6 cords cut and split from our friendly farmer in May. Wonder if some creative tarping might increase the drying rate over our short drying season, al la the "Poly tunnel" (aka greenhouse effect).

    I don't want a swiss cheese firebox in 5 or even 10 years for that matter. Really appreciate you chiming in.
    Chris
  9. woodmeister

    woodmeister New Member

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    Jebatty, you make a good point on when to load I'm only two months into my tarm so the learning curve is getting better, the additive in question is ashtrol or what was refered to as barn lime.I wonder how that would compare to potato skins, though I must say we Irish eat the skins.
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