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Eshland Wood Gun 140. Please Help! New operator with zero gassifer experience

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Green Mt Heat, Dec 11, 2013.

  1. Green Mt Heat

    Green Mt Heat New Member

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    Hello All,

    I just picked up a used Eshland wood gun 140. I have been heating with wood since I was a kid and I have over 12 years of conventional wood boiler experience. I have no experience with a wood gassifier boiler. I just installed the Wood Gun 2 weeks ago, I have been learning a lot, but I have many questions.

    1. So far one of my biggest issues is "puffing" or pre-ignition to tell you the truth I'm not sure what or why the boiler is doing this. I have installed the outside fresh air piping which has reduced the smoke in the room. It seems that this happens when I add 25-30% load of wood in the firebox for a overnight burn. An hour or so later the smoke detector is going off and the WG is puffing? When I open the load door I have noticed that the wood is on fire on the "top" of the pile of wood. When I have only 3 or so pieces of wood in the firebox at a time this "puffing" does not happen. The wood was processed this passed spring so I wouldn't think it was "to dry"? What other reasons might cause this "puffing"? I have closed the manual air valve all the way, still does it. Tonight I will only put in a few pc so hopefully I can get some sleep and not smoke up the house! I have a good draft on my chimney (I ran a natural draft wood boiler for the last 6 years with no draft issues).

    Any ideas or experiences with the wood gun "puffing" would be greatly appreciated. As a matter of fact any tips that would be helpful to a new WG operator would be great.

    Thanks again

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  2. mustash29

    mustash29 Feeling the Heat

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    The Wood Gun cycles on and off, correct?

    It sounds like a wood gas explosion. The remaining wood sits there and bakes during dormant / idle times. When the combustion blower / exhaust blower kicks on and the firebox gets fresh air it sort of goes BOOM and puffs out everywhere?
  3. maple1

    maple1 Minister of Fire

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    I think mustash has it, and I think that's a common WG occurance. Fire gets suffocated, then when it gets told to turn on again, the gases build & then ignite all at once with the gush of fresh air. Hopefully there will be some WG owners along shortly with some hints. I think it was also highly recommended to install a smoke hood over the loading door, ducted to outdoors with a fan in-line. I cobbled up that kind of thing for my old boiler (not a WG) - I turned the fan on before I opened the loading door, then when I turned it off after loading & closing the door it acted as fresh air combustion intake as the drafting boiler would just pull air back in through it. Not sure on your fresh air piping, or if you have a hood, but maybe you could do something like that with the air inlet you have. That won't do anything about the puffing though - but might help get the smoke outside quicker.
  4. muncybob

    muncybob Minister of Fire

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    Are you getting explosions in the firebox or is it puffing/huffing(no explsosion but you can feel and hear the unit "wheezing")? The explosions are normally caused by gasses igniting and usually when it has short cycled(turned on again very shortly after a burn). To resolve this my aquastat is set using a 30 degree differential(off at 190 and on at 160). Have not had an "explosion" since. The huffing usually occurs when the firebox is overeloaded and not enough oxygen in the box. I rarely get this anymore as long as I only load up to barely half full which is usually good enough for 8 to 10 hours depending on the call for heat/dhw. Even still, if it does huff I don't have the smoke problem you described.
  5. CTFIRE

    CTFIRE Member

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    Green -
    I would adjust the air damper on the intake. You should try around 3/4 closed. You having it closed all the way is limiting the 02 too much. also I wouldn't have it all the way open. 3/4 closed seems to be the best for a bunch of us
  6. avc8130

    avc8130 Minister of Fire

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    I wouldn't call it "common".

    I find mine runs best with the damper WOT. The Wood Gun relies on excess oxygen to burn the wood and gasses produced.

    A tight stack of wood with larger splits also helps prevent puffing. The WG seems to like to be treated like an OWB.

    ac
    Fred61 likes this.
  7. Fred61

    Fred61 Minister of Fire

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    Open damper, larger splits and perhaps mixed with wood that has poor coaling qualities such as pine or hemlock.

    I think we're talking about puffing during the burn as opposed to the explosion commonly experienced upon re-start due to short cycling.
  8. avc8130

    avc8130 Minister of Fire

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    I've never been able to get my WG to "short cycle". Running at 30F differential the "natural" calls for fire are far enough apart. The only wood gas explosions I had were caused by running the cycle timer. I seem to have stopped them entirely by adding a delay relay to the air damper. My damper opens 20s after my fan kicks on.

    Puffing is definitely caused by too much surface area burning and the inability to get sufficient oxygen to support the constant burn rate. Closing the damper doesn't help this, at least not after it has started. Closing the damper might help keep the fire from expanding to the point of getting ahead of the oxygen supply in the first place, but once the puffing starts not much short of cracking the door to introduce enough oxygen will help. This is a common issue with just about all boilers.

    ac
    Fred61 and maple1 like this.
  9. Fred61

    Fred61 Minister of Fire

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    It's almost like dieseling. The explosion blows out the ignited gasses and by the time enough oxygen is introduced there is a build-up of volatile gasses set to explode. It is self perpetuating unless you can find a way to interrupt the timing.
  10. Green Mt Heat

    Green Mt Heat New Member

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    Wow thanks for all your support, this website is a great resource!

    Last night I only loaded the boiler with about 6 split pc of wood and I was not woken up by the smoke detector! The down side was I was out of wood by 4 am... I put a few more pc in to get me to 7 am but it was out of wood again @ 7 and not enough DHW for a shower.. This boiler is like sleeping with the enemy (one eye open all night). On the flip side I dont trust this thing enough yet to put more than 6 pc in before I leave for the day to go to work so when I get home the fire is out and the fan has been running for hours with outside air cooling off the boiler. This seems very counter productive, are there "new " controls that have a "low limit" temp cut off that will not allow the fan to run when its out of wood? the firebox in this thing is twice the size of my old Van-Wert wood boiler and that would make it through my day @ work all but the coldest days. With the WG I'm afraid to load it up in fear that I will come home to a house full of smoke?

    The puffing only happens when the fan is on and the unit is calling for heat. I will try opening the manual draft damper to 3/4 open and I can adjust the differential to 30 degrees.

    All of you WG owners.....Are you always careful how much wood you put in the firebox because of this problem. It would be nice to be able to utilize the firebox size to make it through the night. Tonight it is going to be in the single digits again if not 0.. I would love to fill the box 30% so I had enough DHW in the morning to shower... but not to much wood so I'm up all night with the outside door open airing out the smoke.

    I understand that getting a new boiler online and learning its quirks is like getting into a relationship with a new girl, its going to take some time. Sad that my old boiler sprung a leak we had so much time together we were like soul mates.

    Please keep the experience and ideas coming, you are all a big help!
  11. Fred61

    Fred61 Minister of Fire

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    Goodness, you sound experienced. At some point in your life did your old girlfriend spring a leak.
    BoilerBob likes this.
  12. maple1

    maple1 Minister of Fire

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    !!!
  13. avc8130

    avc8130 Minister of Fire

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    6 splits isn't going to cut it all night with the cold snap the northeast is experiencing.

    Yes, the new controls have an aquastat to cutoff the boiler if the water temp drops below a set point. This prevents the boiler from "blowing itself cold".

    I generally don't worry about how much wood I put in the firebox. For Thanksgiving and Christmas I will fill my 180 right to the top and pack as much wood in as I can. I am gone from my house for 16+ hours those days and need the capacity to prevent coming home to a cold house. On a normal basis I put enough wood in to get me to my next expected load while still having some nice coals. After a full year of operation I'm pretty decent at it.

    Where is your smoke coming from? It sounds like you have something else going on creating this massive of an issue to me.

    Can you post pictures of your setup?

    ac
  14. Green Mt Heat

    Green Mt Heat New Member

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    Hi Guys!

    @Fred61 ya that girlfriend I ended up marrying her... after about 10 years she ditched me or (sprung a leak) depends how you look at it.LOL...So ya I do have experience.. And from what I have learned up to this point wood boilers are a lot like women. It takes a few years to figure out how to live with them and then once you get them figured out and things are going ok....well its the end of the road. I will say my 1st wood boiler we could just never get along couldn't figure it out no mater what I did. I ended things my way that time...I sold the damn thing.
    Now that my Van Wert decided to bail out I have embarked on this new adventure with Wood GUN! And I have to say WG and I are off to a rough start with this puffing chugging crap! It's 9 degrees out and the damn thing is puffing away! I put about 8 split pc in to see if the air adj. would help but it's
    I did adjust the manual damper and I have concluded that more air is defiantly better. I have the damper almost all the way open now and the pufs were a lot closer together than when it was at 25%. I plan on letting it burn down before I go to bed and then just put a few splits in b4 bed. I will hae to get up and add more in a few hours which is crazy because the firebox is huge and i cant take advantage of it.

    Smoke comes out where ever things are not completely sealed like around the shaft by the manual damper, I removed all the shims from the loading door so it would seal tighter. It wouldn't leak smoke when it was running normals but when it was puffing It would come out the bottom of the door.

    Please chime in with more ideas.

    Thanks again you guys are great!
  15. 711mhw

    711mhw Feeling the Heat

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    Yeah, you can not treat the chimney piping casually. It requires special attention to all the pipe joints with that big fan. I stuff the fire box full to the top but they do seem to like big wood or even unsplit, (no one hander's) and good and dry ofcourse.
  16. bpirger

    bpirger Minister of Fire

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    Is it a problem when it is burning flat out during a demand call or just when the call turns on and it is getting going? I assume you have no storage....it is something to think about going forward. You can then burn flat out to charge storage (big tanks of hot water) and then the fire can go out and you draw off storage. Depending on storage and your load, you can be burning just one fire a day.

    Wood was cut/split this spring? Might be a little wet.

    Puffing is from an uneven mixture of fuel (wood gas) and oxygen. When there's not enough oxygen to burn the fuel and suddenly there is, you get the little explosion. Then this cycle repeats. With my Garn, when I have too many little pieces making too much wood gas, it will puff. This can be quite wicked, with the door pulsing, the external air intake pulsing, the overhead door pulsing! Only once have I seen smoke puffing out. I'd never open the door though at this time, I'd expect a big flash out.
  17. maple1

    maple1 Minister of Fire

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    Are you sure everything is clean inside? Nothing blocking air from getting to where it's supposed to get? No blocked air passages anywhere?
  18. avc8130

    avc8130 Minister of Fire

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    Green,

    Pics of your setup please.

    How big are your splits?

    ac
  19. Fred61

    Fred61 Minister of Fire

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    I was about to ask about split size as avc did.

    Had a couple thoughts. Nothing I ever tried when I had my 140 but I have even more experience now and along with the Boiler Room, I've given these problems more thought.

    Now and then I also get this phenomenon with my EKO and much of the time it is of my own making. The unit will be running fine and I can't leave "well enough" alone. I'll open the door and poke the load so it completely covers the nozzle with a thick bed of coals. Immediately after closing the door it will start puffing and will continue until a hole is burned through the coals. I think this is telling me that the coals are blocking the gasses from going down to the secondary chamber and igniting in the upper chamber. Although the Wood Gun and the Eko are different in that the Eko has secondary air injection and the Wood Gun supplies excess air over the top of the fire in order to ignite the secondary tube the result is still more or less the same.

    Thinking out loud here I'm wondering if you keep a channel open to the fire tube if that would make a difference. Never tried this but how about laying some slices of firebrick across the nozzle to help keep your wood up from the nozzle or maybe load some shorter splits toward the rear of the firebox and keeping the front of the nozzle completely free of burning coals, allowing free flow of air into the secondary chamber.
  20. avc8130

    avc8130 Minister of Fire

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    Fred,

    Thanks for bringing that up, I almost forgot about 1 of the most effective techniques!

    Green,

    Try raking your coals forward towards the loading door leaving the rear nozzle completely uncovered. Then stack your wood right at the front of the boiler. The idea is to leave the rear nozzle completely open for free-flowing air straight to the secondary chamber.

    If you have really small and dry splits this extra injection of air has been known to help.

    ac
  21. Fred61

    Fred61 Minister of Fire

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    Sort of makes sense. The explosions are obviously taking place in the fire chamber and that's not where the gasses are supposed to be igniting so they must be trapped in the upper chamber. Getting the gasses to ignite in their proper place should improve the situation.

    It's probably a moot point but you and I disagree on which end of the chamber the free air should enter. My thoughts were that the air entering the front would get a chance to do it's work over the entire length of the firetube as it traveled toward the exit.
  22. avc8130

    avc8130 Minister of Fire

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    The rear nozzle suggestion came from AHS.

    I think the idea is that the air goes straight down into the lower chamber and has less of an opportunity to "fan" the fire on the wood itself further propagating the issue.

    ac
  23. Green Mt Heat

    Green Mt Heat New Member

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    Thanks for the tips guys,

    I will try pulling the coals to the front of the box and Keep the airway clear to the combustion tunnel. I have a few logs that I can cut up tomorrow before the storm. I will leave them unsplit and see if that helps.

    Does anyone know if AHS is working on a retrofit part or solution at this point. Has anyone seen a picture of such a device? I guess i could try to fabricate some sort of a heavy steel channel that would act like a duct from the rear inlet down to the fire-grate/ nozzle area. Anyone have any idea how much % to send to the nozzle and how much to send to the firebox? i guess it would be good to make it adjustable? I wonder why all the European gassifiers have secondary air and the WG was never updated to allow for that.. Seems that the back door on the combustion tubes could some how be rigged up to have secondary air if there was a way to meter it and make sure combustion air doesn't come out just oxygen rich air in? Im not an engineer just thinking out loud??

    I would also like to upgrade my aqua-stat to have a low temp shut off so the fan doesn't run when there is no wood left in the boiler. Do any of you guys have these controls on your WG? Could you please post a picture and the name and model of the aqua-stat.

    Update from last nights burn.... I was able to sleep for 6 hours w/o the smoke alarm going off. I opened up the manual draft to 75-85% and adjusted the dif on the aqua-stat to 25 degrees. Hoping to sleep again tonight.

    Thanks again... Talk soon
  24. Coal Reaper

    Coal Reaper Minister of Fire

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    Your wood is not dry enough. Likely secondary chamber not getting hot enough to gassify?
  25. avc8130

    avc8130 Minister of Fire

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    AHS played with a separate secondary air supply. The problem is with the on/off nature of the WG. You would need 2 air dampers and those Honeywell units are quite pricey! It would also add complication.

    I'm not sure why you are having such problems. Something else must be wrong.

    Your wood is fine. I have put oak that was definitely NOT seasoned in my boiler. It burned it just fine. DRY wood is the problem for puffing.

    Get your damper WIDE OPEN. Use big splits.

    For the low limit you will replace your high limit aquastat with a double unit. I

    [​IMG]

    Where are our pictures?

    ac

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