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Clean fire start in gasification boiler

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Nofossil, Dec 23, 2007.

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  1. Nofossil

    Nofossil Moderator Emeritus

    Joined:
    Oct 4, 2007
    Messages:
    3,419
    Loc:
    Addison County, Vermont
    I'm still working on this, and I wanted to share progress and see what others have come up with. My goal is to reduce the amount of startup smoke and the amount of time that it takes to get to gasification / secondary combustion.

    Here's my current approach:

    1) Place a medium sized triangular softwood split on each side of the firebox to make a V in the bottom so that kindling and logs are nudged toward the center as they fall downwards.
    2) Crumple two sheets of newspaper and pack into the bottom of the V, above the nozzle.
    3) Place two layers of softwood kindling (micro splits) widely spaced on the newspaper.
    4) Add two layers of very small (about 3/4") hardwood splits next, also widely spaced - 4 to 6 pieces per layer.
    5) At this point, I'm up to the top of the softwood V, so I'm working with the full width of the firebox. Continue with larger sizes each layer, padding the sides with bigger chunks. Fill to about 3/4 full, ending with splits and small rounds that are in the 2" to 3" range.
    6) Open the bypass damper and the bottom door, and light the newspaper.
    7) Wait 6 minutes. Close damper and bottom door, and switch on controller. Should kick off secondary combustion immediately. Let it burn for 30 minutes, then fill to the gills.

    Some lessons learned:

    1) If you get puffing or pulsing during the 6 minute startup burn, you have too much kindling or small stuff.
    2) If you get a big puffback or 'shuddering' when you switch to gasification, you waited too long.
    3) If secondary combustion does not happen within 30 seconds, one of three things went wrong:
    - The wood was too wet or you didn't have high quality kindling
    - You didn't have enough kindling
    - You didn't wait long enough

    I use a cheap magnetic flue temperature gauge. It needs to be about 250 degrees to be sure of secondary combustion. YMMV.

    What are other people doing?

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  2. Eric Johnson

    Eric Johnson Mod Emeritus

    Joined:
    Nov 18, 2005
    Messages:
    5,705
    Loc:
    Central NYS
    I almost never get puffback and I don't have a problem with ashes building up in the firebox; they just go down through the nozzle when I'm raking the coals. In cooler weather I rarely make a cold start, because the thing is going pretty much all the time.

    But when I do a cold start, I usually stick to pine cones, a little paper or cardboard, a few strips of maple bark and several small limb pieces. I open the ash door and the bypass damper and go back into the house for a cup of coffee. On a good start, it will be burning pretty clear by the time I get back out there, at which point I toss on a few more bigger pieces, close the bypass damper and the ash door and turn on the blowers. Hopefully there's no smoke from that point on. But that's not always the case. Sometimes it smokes and you can hear the nozzles igniting and going out as they try to get up to temp.

    I backed my secondary air adjustments out to 6 turns and the result has been cleaner, faster startups. Most of the time.
  3. Grover59

    Grover59 Member

    Joined:
    Nov 28, 2007
    Messages:
    168
    Loc:
    Central Maine
    At this time I don't have any cold starts, however as soon as the tank is going I may have. I start mine with small pieces of hard wood no kindling I don't have much at this time it takes longer to get to gasification. I know if I started with kindling and got it going good I would have a faster start and get to gasification much sooner.

    Steve
  4. brad068

    brad068 Feeling the Heat

    Joined:
    Nov 20, 2007
    Messages:
    440
    Loc:
    Central Wisconsin
    Procedures for firing up my boiler.

    1. I turn on the draft fan timer to @3hrs. and then open the door. 2. I grab a few pieces of cardboard that I have cut up and place them on the floor of the firebox. 3. I throw in a wheelbarrow load of wood (its a smaller sized wheelbarrow). 4. I light the cardboard with a propane torch, usually about 10 seconds and shut the door. It has always taken off and I have yet to relight it. I use cardboard to light because it seems to work the best. I tried newspapers, old rags, plastics,etc. but they all seem to ignite and burn up to fast and never get the wood burning. They also make the boiler go crazy. You certainly do not want to open the door when burning alot of paper, it will blow your hat off if your not careful. That's basically it. I'll come back and check it when the burn cycle is over and theres not much left in the fire box, just alittle more ash than when I started it. I won't repeat this process for about another 24-36 hrs.
  5. antknee2

    antknee2 New Member

    Joined:
    Oct 7, 2007
    Messages:
    253
    Loc:
    NY
    Garnification Your system must be ultra efficient ,is it close to condensing ? What is your heat load consist of ? Anthony
  6. Seyiwmz

    Seyiwmz Member

    Joined:
    Dec 11, 2007
    Messages:
    38
    Loc:
    Upper Michigan
    I haven't made too many cold starts in my 3 years. Maybe a dozen or so. I have no storage right now and burn for weeks until I take it down for a clean up. So, to be able to start up in 6 minutes is really fast. I usually take about 20 minutes or so until everything in my system is up to temp. I use alot of paper and top it off with cedar slabs and a few chunks of the firewood. The inside of my boiler is usually caked with wood tar, so start ups can get a little smoky out the chimney. I wish I had storage. I got another line on a 500 gallon propane tank. Hopefully this deal don't fall through like the last one for me. The local scrap yard don't sell them because of the liability they would have bla bla bla....ect. A new one is $1200. I just took mine down and will start up after Christmas using the "firebrick nozzle block off method" you guys talk about. Happy Gasifing
  7. Nofossil

    Nofossil Moderator Emeritus

    Joined:
    Oct 4, 2007
    Messages:
    3,419
    Loc:
    Addison County, Vermont
    My pattern is a new fire every day or two. I run it flat out for an average of about seven hours, then live off the storage until the next fire. Depending on how long I ran it and how cold it is, I generally build a new fire every day or two. I skipped yesterday, for instance. I had to build a fire this morning, though, because the storage ran out of usable heat.

    With this pattern, I burn really clean, but I'm building a lot of new fires. With a larger tank or radiant heat, I could skip days more often.
  8. bbb123

    bbb123 New Member

    Joined:
    Dec 6, 2007
    Messages:
    95
    Loc:
    Coxsackie, NY
    I'm running mine once a day. Tank temp is usually around 140. I use one couple inch diameter piece of soft wood with 1/3 fire starter stick and a couple small logs on top (don't smother starter). Leave damper bypass door thingy open for couple minutes. Check if decent flames load it up close bypass and usually gasifys immediatly or within couple minutes.
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