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Greenwood boiler problem

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by joeski206, Nov 9, 2007.

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  1. td182a

    td182a New Member

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    Anthony D, you have a very proffesional setup! Looks good.

    I am thinking I should get a draft meter rather than just guesstimating. What is the brand of the one you have in your photo? Works well?
    As for stack temp, is that one of the magnetic ones in the photo? Works well?
    I suspect the temp at the chimney top is not very high, I can hold my hand in it easily. The Greenwood is only supposed to be 350 or so coming out of the stove. By the time it travels through 21 ft of Masonary chimney, its cooled off substancially.
    As for a buffer tank, I have the Greenwood circulating the existing oil fired boiler, using its water volume for a buffer. I have the supplied high temp switch hooked to a relay controlling the house heat, if the water outlet on the stove reaches 200 degrees, the house heating system kicks in. I also have a 90,000 BTU exchanger hooked in for DHW, the electric heater is shut off. We have 4 kids, so hot water is in constant use!
    I have 56 inches of 8 in black pipe not including 2 90's, going too 21 feet of 7X11 clay lined masonary chimney inside the house and integeral with another flue from a Pacific Fireplace insert upstairs burning the same wood very well and cleanly. I just installed a draft inducer which has reduced the smoke problem, and I think it has somewhat reduced the creosote problem.

    I will try to attach a photo showing the creosote from the draft door and leaking from the chimney.

    Attached Files:

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  2. Eric Johnson

    Eric Johnson Mod Emeritus

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    Do you have a nozzle or nozzles in that boiler?

    I agree that your problem is most probably going into idle and staying there long enough for the creosote to form. Usually that's the sign of an oversized boiler for the heat load. And you are correct, hot water storage would be a good cure. I think the reason some mfgs. say you don't need storage is more to gain a marketing advantage than a reflection of the ability of their equipment. Refractory can't compare with water, IMO, as a way to move and store heat, especially in the kind of volumes you need with a big boiler serving a moderate heat load. Getting back to the marketing--if you didn't need storage, it would represent a few thousand dollars in savings. That would be a perceived competitive advantage. JMO, of course.

    You might also check your air settings. On mine, not enough secondary air will cause smoke, although even during idle, I don't seem to get creosote. But it's a different design.

    Getting back to my question about nozzles: On a gasifier like the EKO, you can block off all or part of a nozzle to effectively cut the boiler's output, resulting in longer burns and less idle time. It's not a perfect solution, since the boiler was designed to burn with full nozzle power, but it does work and is one way to minimize idling without storage. You can also learn to fire the boiler according to conditions, which is usually just a matter of observation and experience.

    EDIT: Or, forget everything I just said and talk to these guys:

    http://www.hearth.com/econtent/index.php/forums/viewthread/11801/P15/

    Similar boiler design, I believe.
  3. SteveJ

    SteveJ Member

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    Eric,

    I agree - the Greenwood looks like the Seton.

    First and foremost, I would suggest testing and sealing all leaks as shown by Anthony in http://www.hearth.com/econtent/index.php/forums/viewthread/11100/P0/.

    Anthony is the expert on this boiler - try to get all measuring device he suggests.

    Hope this helps - maybe we can start a Seton/Greenwood tips and tricks thread?

    Steve
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    Please do.
  5. wdc1160

    wdc1160 New Member

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    I would like to point out that this is the most viewed post on hearth.com.
    At first I didn't understand why, but i think that this explains it:
    "I See Dead BTU's" has used the term"goo" 10 times-- then defined its compostion and that he picked an electronic posting fight with "kuribo" -- and that he still has Pirro as his avatar.

    It's got the makings of the best post on the forum no doubt.
  6. Eric Johnson

    Eric Johnson Mod Emeritus

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    What were we talking about, again?
  7. wdc1160

    wdc1160 New Member

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    The orginal guy who posted the question withdrew his membership from the forum -- So I don't know
  8. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    LOL, ok, so, I am from NY and I think the ex-Mrs Pirro is hot ;-P . . . . Anyway . . .

    I was just pointing out that it's easy for an 'expert' to say you shouldn't have . . . [insert a word that rhymes with Dew, here] and that if you do then you are not gasifying and are suddenly no more efficient than a typical OWB. If you shouldn't ever have creosote, then why do hydronic units like the EKO (no relation to the Electric Light Orchastra) have cleaning devices? Yeah, it would be great if we all burned 10% moisture content wood, always ran full out, always had all the wood in the load hot enough to not supress combustion, yada, yada, yada. Anyway, my beef would be that the aforementioned engineer made it sound that you are either 'gassifying' or burning inefficiently. Would that mean that before, say, an EKO or other forced induction unit gets up to 'gassification' it is burning at say 50%, then it jumps right to 85-90% when it hits 'gassification'? I doubt it. But I am most definitly NOT an engineer. ;-) It's all good.

    Eric - the GW prides itself on being much 'simpler' than the forced induction units, which is to say we don't have nozzles, etc. We have four airtubes at the back of the primary combustion chamber. These are either closed off completely, or open completely. No fan. The smoke path goes up the back of the box, is forced forward slightly by the shape of the primary combustion chamber, then has to go bac and down to exit the unit. Many less things to tinker with on these units, but likely also not quite as efficient as the EKO or other well-designed forced induction units bantered about here everyday.

    LOL< getting back to our original poster, one generic thing I would say is give it a year with any new hydronic to figure out what you're doing. And measure stuff. Don't assume exhast temp, don't assume draft. And keep asking questions here, despite obnoxious pricks like me :lol:

    Jimbo
  9. Eric Johnson

    Eric Johnson Mod Emeritus

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    You're only an obnoxious prick when you drink, Jimbo. Otherwise, you're just colorful. And you pass on a lot of good information.

    I agree with your assessment of the time it takes go get comfortable with any new woodburning appliance. It probably takes longer than that to get really good.

    The EKO's hx cleaner assembly basically just knocks fly ash and soot back down into the ash pit. I've never seen anything like the "goo" in some of those pics leaking out the back of the Seton and Greenwood on my rig. But it looks a lot like the creosote that my other boilers have produced at times. Of course, I don't burn wet or green wood, so I might see it if I did. Normally, you stand a chance of burning that stuff off with a hot fire. But I'm trying to figure out how you get it out of your chimney with stack temps below 500.
  10. wdc1160

    wdc1160 New Member

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    Jimbo your preaching to the choir. As a NY'er your genetically predisposed to not lettting others talk about your goo. I think that you probably will have a following/groupies after this set of posts. You'll be the Dennis Rodman of the Boiler Room. I'll shut up now so I don't interrupt your electronic ACE whooping.
  11. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    LOL, Dennis Rodman was a Laker for a while, so it's all good. Maybe I should 'find' an avitar of Pirro wrestling a Laker Gurl . . . that should give me a whole new following :coolsmile:

    Anyway . . . Eric . . .yes, I definitly had more of the soot/water mix last year, when I was burning a huge Basswood tree (the tree was taken down during house building, contained probably 1 1/2 FULL cord, yet produced enough heat to heat my house for like a day and a half!!!) and other 'junk' wood that needed cleaning up. This year, a combination of better wood (read, lower moisture content red oak) and more experience (read, leave the damn load door closed for 8 hours at a time! and don't over fill the box) and the aforementioned 'gunk' is way less this year.

    Jimbo
  12. kuribo

    kuribo Feeling the Heat

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    Let me try to explain this one more time:

    There is regular combustion which releases the volatile components in the fuel. If temperatures are not hot enough, and/or there is not sufficient oxygen, these volatile compounds go up the flue, attach themselves to the fire box, etc., where they condense forming tars, creosote, and other "goo". These volatiles contain significant quantities of energy. If temps aren't high enough, they are condensing, they aren't being burned. If they aren't being burned, energy is being wasted. If energy is being wasted in this manner, gasification and it's higher efficiencies are not being achieved. This is the OWB system. Smoky, tarry, "gooey", lower efficiency.

    If temps are high and the oxygen sufficient, these volatiles are burned and release their heat energy. No visible smoke, no tars, no "goo". High efficiency. This is gasification.

    If you are getting smoke, tars, creosote, "goo", you are not operating at gasification efficiencies because, you are not gasifying throughout the burn.

    The cleanout system in the ECO and others of this design are there to shake loose soot and ash, not tars and creosote.

    And, yes, before gasification starts with the ECO and the others, they smoke a bit and are not operating at gasification efficiencies. Gasification starts once the fuel has been pyrolized and starts producing "wood gas".

    This can all be found through a bit of poking around on the net. No mysteries here....
  13. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    However, if you read http://www.hearth.com/econtent/index.php/forums/viewreply/133148/

    you will see that another expert says "That is, the process by which solid carbon/organic fuels liberate combustible gas upon application of the required external heat flux. This process is endothermic, as it would cease upon removal of the applied heat flux, and is therefore, not a form of oxidation. No matter what one uses to burn wood, anytime a solid fuel is involved in a combustion reaction, gasification or pyrolysis occurs. Molecules from solid fuel cannot participate in oxidation reactions when they’re still involved with the solid. When you observe any solid fuel combustion you are observing two separate categories of chemical reaction."

    Not trying to get into a pissing match with anyone, just saying that many times experts and salesman do not agree with other experts and salesman. And poor working stiffs like us have to ferret out the BS.

    I wonder if the original poster gave up on his GW yet . . . maybe I could pick it up cheap for some 'modifications' . . .
  14. kuribo

    kuribo Feeling the Heat

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    And if that liberated combustion gas does not burn, it does not release its energy and exits the flue and/or condenses forming creosote.

    It is certainly true that anytime solid fuel is pyrolized (burned), it releases gas, which in the literature is termed "gasification". What is important is whether or not the released gases are burned or allowed to condense. In the vernacular, "gasification" has come to mean not only the production of these gases (which happens whenever there is combustion) but the burning of these gases under high temperatures, leading to high efficiencies. All boilers, including OWB's are technically "gasifiers", but only what is called popularly a "gasification boiler (EKO, et al), burns the volatiles and has high efficiency. The others produce the wood gas, but do not burn it (OWB's)...
  15. wdc1160

    wdc1160 New Member

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    I actually had gone back to read what your goo may consist of. And tried to think of why it may form.

    In one of your posts you thought some of the goo may be some of the refractory matierial?? I am going to assume that is a typo.

    I thought the refractory matierals in the GW may facilitate condensation. Normally this is a horrible
    thing.

    The refractory material in the GW isn't going to have the same reaction as the metals in the other post.

    maybe the condensation mixed with ash isn't an alarm bell. Maybe it is an advanced condsation ash cleaning feature that deadBtu's always wanted. ACACF for short.
  16. antknee2

    antknee2 New Member

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    This is gauge I use, it's overkill but a great tool for boilers that rely on natural draft like Greenwood , Seton , Adobe , Greenfire . I find just by a quick glimpse at the draft gauge and the internal stack thermometer you can tell if tell if burning clean and efficient , sometimes it needs a couple dry splits to bring it up to speed . This is a direct quote from the Seton boilerr instruction book . If the exhaust temperature drops below 250 f before it exits the top of the chimney it will restrict the draft necessary for clean burn, this will cause the pressure vessel to form creosote and will cause the boiler and the chimney to make water that will corrode the boilerr and the chimney. Anthony
    http://www.valuetesters.com/Bacharach-13-7018-MZF-Draft-Gauge.php
  17. SteveJ

    SteveJ Member

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  18. sparky1961

    sparky1961 New Member

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  19. sparky1961

    sparky1961 New Member

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    look at your pressure vessal to see if u have a build up on the pipes. The lower part of the vessal at the rear of your boiler could be getting clog with creosote that will cause draft problems i have seen that happen before. also if u can try burning large wood it makes a huge huge inprovement !!!!
  20. jebatty

    jebatty Minister of Fire

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    Goo -- no goo. Got my first goo which told me much and fits the discussion. Reloaded my Tarm with the usual pine, shut the bypass damper, forgot to turn on the draft fan. Came back a couple of hours later, and goo was dripping from most of the places where goo could drip.

    Yeoman's conclusion -- unburned combustion gases/products condensing everywhere they could and hijacking gravity to their final resting places.

    Never happened before or after. Being a few watts short of 100 sometimes makes everything brighter.
  21. jebatty

    jebatty Minister of Fire

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    Forgot -- soot, whether or not mixed with water, in the ideal gassification world, should this even exist? Isn't soot a form of carbon, which when heated in the presence of oxygen burns, giving heat, which is why we have boilers? Since none of our boiler are 100% efficient, there always will be some soot/carbon, but the less we have the better?

    And if soot is mixing with water to make goo, where is the water coming from? Shouldn't the chimney be hot enough to vaporize water so that water is not condensing, to mix with soot, to make goo?

    Don't we all want goo-gone?
  22. td182a

    td182a New Member

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    Thought I'd post an update on my GW 'goo' problems. As some posters have mentioned on this site, the GW and possibly others, are not like the OWB in that you only put in enough wood for the conditions at the time in order to run a certain length of time. (does that make sense??) I have had OWB's and twice a day you go out and top them up to the max. When I did that with the GW, it was idle so much it ran the 'goo' out every orifice. I now try to keep it burning with hot embers, blue flames being the best. I also don't open the door unless it's burned down to embers, and try to let it burn everything before adding more. I have the draft fan (same one as on their website) set to come on when the damper door opens, and only open the door when the fan is running. I would say that I no longer have the big 'goo' problems, and have about 2 gallons of ash every month from reasonably dry bug kill pine.
    I had a problem with the Aquastat which caused the stove to overheat, which caused the low water sensor to malfunction. I called GW, they sent me out a new Aquastat & low water sensor ASAP. Have too give them credit. I have also wired the circ pump into an UPS unit in order to prevent overheating in the event of a power loss. It has already saved a potential problem when the power went out for a 1/2 hour or so.

    Overall, I would have to say that I'm reasonably satisfied with the unit, it's simple, reasonably priced, and better to use 'free' wood than gas/oil/elec. Just have too install a draft inducer, load wood in relation to heat needs, don't open the door unless the draft fan is running & wire in an uninterupted power supply to the pump (but allow the draft door to lose power) in case of a power failure.
  23. antknee2

    antknee2 New Member

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    Hi td182a I like to read follow up reports , helps with future problem solving . Keep up the clean burning . Anthony
  24. jebatty

    jebatty Minister of Fire

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    I hope no one already mentioned this, but to my mind with gasification boilers there is a good reason not to add wood before the prior load has burned down to low coals, just as td182a has discovered.

    1) the prior wood load has brought the boiler up to temp,
    2) the most volatile (hottest) gases burned off in bringing the boiler up to temp initially,
    3) the partially burned wood and then coals are maintaining the boiler within operating range (there may be some idling during this period), and
    4) as the whole load burns down to low coals, the boiler actually may cool down some (to 170 or so).

    At low coals, now add wood, and the new wood will really take off, burning off the hot burning volatile gases, and the boiler fairly quickly again will brought up to full temp. By this time the boiler is back to (3) above, and all is good.

    If fresh wood is added at stage (3), with the boiler already up to operating temp and maybe even some idling, the new wood will really take off, burning off the hot burning volatile gases, and extended idling periods may result. During these idling periods, if long and repeated, the fresh wood, still loaded with moisture and some volatile gases, will smolder, producing creosote and water vapor. These head up the flue, condense and maybe even wash down ash and creosote fines stuck to the chimney walls -- the result being goo running down and out any place available.

    I had a small "goo" problem accidentally, which gave rise to this thinking, when I added fresh wood to a half burned load. In doing this I shut off the draft fan so smoke wouldn't come out the firebox door. But then I forgot to turn the draft fan back on. The new wood smoldered, and a minor goo problem just as described was the result.
  25. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    I think the hardest thing for me personally is getting it through my head that you have to put an 8-hour load in, shut the door, and not open the door till the temp drops below say 175* (aquastat set at 190* with 10 deg +/-). If I did this for the whole season, I bet I would have burned less wood. This is the one argument in favor of either full insturmentation or having the unit inside.

    But hell, when it's 40-50* in March, it's easy to load it and leave it. Even Aspen will heat the house at this temp :cheese:
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