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gasifier wood consumption

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by barnartist, Dec 30, 2007.

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  1. barnartist

    barnartist Minister of Fire

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    I have been reading here for a while, just decided I needed to join in. I have had an eko 60 with 500 gal of storage, im in my 3rd season of burning.
    I feel I have come to know my sytem better than my wife, and she would agree. I have plumbed and replumbed by trial and error many times in many different ways.
    I have even had to dig out my crappy homeade 75 feet of ground line and replace it with the good stuff from central boiler. I am asking for everyone who has a similar system, actually anyone who burns wood to let me know how much of it they are using. I have a well insulated 3200sq house, my sto tank is extremely well insulated,
    and I cant keep enough wood around for it. As of today, I am officially dissapointed, and I am hoping that there is something I can do to burn less wood.
    I know there are not alot of details here. Anyone with a comment will be helpful. I'd just like to see what everyone elso is consuming wood wise.

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  2. Eric Johnson

    Eric Johnson Mod Emeritus

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    Welcome to the Boiler Room, barnartist. Good to have another EKO 60 owner on board.

    How much wood do you burn in a season? Did you have another wood burner before the EKO that you're comparing it to?

    I've always burned a lot of wood. I love to cut it and handle it so I don't mind, but we like to keep the house nice and warm, and my basic approach has always been to put my meager resources into wood heating systems rather than things like new windows and doors.

    Anyway, last winter I burned about 13 full cords with a conventional wood-fired boiler. This winter with the EKO I expect to go through around 10. But I'm heating more space this year and keeping it a lot warmer. We've got an 1865-vintage farm house with about three additons of varying age, for a total of about 3,000 square feet of moderately-insulated house, plus a single-pane glass greenhouse, which I am now using since I can afford to heat it.

    So I'm pretty happy with the 60 so far. Like you, I'm always fooling around with it, trying to make it better. Do you get any smoke when it's up to temp? Sounds like yours is in an outbuilding, like mine. Details, man. Let's dig into it.
  3. barnartist

    barnartist Minister of Fire

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    Wow, thanks for the reply.
    Well, I started the season with 8.5 cords of wood, the good stuff cut split stacked last april. I was sure this year to have it ready so I did not hear my wood was green.
    I use an air exchange in my furnace id does most of my heating. I have a flat plat for my DHW, and I have a portion of my basement in slab radiant, that I gave up on because it sonsumes so much wood. This is a seperate issue, one that I got some bad advice on, and understand the mistakes I think made on it.
    Anyway, my boiler sits about 75 feet from the house, in a "lean-to" attached to my garage. Inside my insulated garage is my converted 500 gal propane tank. My plumbing is this, I send my hot from the eko with a leg to the house, and a leg to my garage (air)furnace. My garage furnace by the way never kicks on, mainly because I get heat radiated from my pipes, the 30x40 garage stays between 60-70 degrees this way. My demand return goes into the bottom of my virtically standing tank, and out the top for a return to the eko's bottom. I also have a laddomat installed there.
    My dissapointment is this, I started the season doing better than last year because of my new and improved ground line. Man, I wasted a ton of heat the previos years lost in the ground, and I have pics of the steam comming from the dirt as we dug up the old stuff. Anyone else reading this should not go cheap in the ground lines as I did. Meanwhile, it seems that I should only need to load twice a day, especially given it has been pretty mild. I have been running the system by loading wood when I am down to the last of the coals, or enought to ignite the next load. However, if and when I try to let my tank get down to say 160, so that I would cyle my eko less and burn hard more, I have a tough time recovering.
    Anyway, I have probably used 4.5-5 cord already, and probably load 2.5-3 times a day. I idle most of the time once the wood is at a good burn.
    Maybe I have unreasonable expectations. My house is well insulated, r-40 in the ceiling. Again the house is approx 3200, less than Zenon's house and he uses a 40, but he may also use his coal heater.
    Look forward to your thoughts.
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    As I understand it, there are several places that you lose efficiency with a big gasifier like the 60. One is up the stack. Do you know what your stack temps are? They should average in the 300 degree range. If they tend to be higher, then you've got heat going up the stack instead of into the water jacket. You need an internal, stack probe thermometer for that. Or, you can buy a turkey thermometer at Walmart for $5 that will work just as well.

    Does your boiler have the mechanical heat exchanger cleaner (the handle on the left side)? If not, you may need to clean your heat exchange tubes. When they get sooted up, the heat transfer is affected and your heat will go up the stack.

    Another place to lose heat is by burning green wood. If you cut your wood last April and stored it outside, it still might not be dry enough to get good gasification, and you'll lose heat up the stack in the form of steam. Your firewood needs to dry for at least one full year in order to be completely dry--two is even better. I've burned plenty of wood cut the previous spring, and it's rarely dry enough to work well in a gasifier, especially if it's been a wet summer.

    The reason I asked about smoke is that it can indicate green wood or an improper air adjustment, both of which can affect efficiency. I had to open my secondary air adjustments up a full 6 turns in order to get a consistently clean burn.

    Idling is another place where gasifiers--and big gasifiers in particular--lose a lot of efficiency. I'm not exactly sure why that is, but they're much more efficient when loaded up full and burned full-out. If you have a 500-gallon storage tank, then your boiler really shouldn't idle at all. Sounds to me like maybe you have a problem with that setup, but I'm the wrong guy to ask about that. We have a few other members with pressurized storage and hopefully they can make some suggestions. Termite is one, and he doesn't live that far from you. I don't know anything about Tekmars or other mixing valves, but that could be something to check. And I've always found heat exchangers to be potential sources of inefficiency and heat transfer problems.

    You might want to unscrew the plate that the blowers are mounted on and take a look at the secondary air tubes. They're tack welded to the boiler body and occasionaly the tack welds will break, allowing the tubes to move forward into the air adjustment valve. You know this has happened if you can't turn the adjustment screw. If that happens, it's impossible to get the right air adjustment resulting, I suspect, in less efficiency. I have a picture of that if you're interested, because it happened to me.

    So that's my brain dump for the moment. Forgive me if I've made some points that are obvious, but I think we're all kind of still in the experimental stage, so there's no such thing as common knowledge. I'm sure others will chime in before long.
  5. barnartist

    barnartist Minister of Fire

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    I keep close attention to all my temps. I agree about the stack. I try and keep it between 300-350. Much of the time its 250 because i suppose it is idleing.
    I have homade inserts in my tubes, I made 2 kinds. The 1st set are metal strips that I twisted that mimic the new syle. I made them too wide though and they are
    tight to get in and out. I need to make a new set of these so they fit better. The second set works ok, they are thick rods with small washers welded every 5 inches or so. they seem to attrct more moist ash and I have to clean them more often. Early this morning, I removed them completely for a while, just to see how things go.
    I have to believe my wood is dry, but you seem to have more years under your belt and would know as much. We had one of the dryest seasons here for years, and the wood seems to be most dry and cracked up. It is a mixture, but alot of cherry, some oak, poplar.
    How do you think you would do with say, a Central Boiler?
  6. Eric Johnson

    Eric Johnson Mod Emeritus

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    Hard to say. My first year with my old boiler, I burned 21 cords and it couldn't keep up when the temps were below zero, which they were for a lot of the winter. I made some piping changes and insulated a little better, and eventually got it down to 13 cords.

    It sounds to me like you've got a heat exchange problem. If your tank has trouble recovering and your boiler goes into idle at the same time (not sure if that's what you were saying), then obviously the heat isn't moving correctly and you're wasting heat up the stack and everywhere else your system is vulnerable to heat loss. The year I burned 21 cords, my flat plate heat exchanger was piped wrong, so that it didn't transfer much heat. The water just went round and round, exaggerating all my inefficiencies on every trip. But I suspect you've considered all of that already.

    You can't tell how dry wood is by looking at it. The only surefire way is to put a meter on it. I think they're pretty cheap. You need to split or cut a piece of wood to take the measurement, because the surface might be dry, but the inside wet.
  7. leaddog

    leaddog Minister of Fire

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    With the storage you shouldn't have your boiler idleing. It should be into a full burn untill it is out. If I understand you right you are trying to run the heat from the boiler thru your house and when you aren't demanding heat it goes into idle. That is the problem, you need to be then running the heat into the tank. I have my house pulling heat to the house going to my dhw tank and returning to my storage. The boiler is piped to a heat exchanger into the tank. if the boiler temp is up to 170 I have a valve open to also send it to the house circut. this is controled with a aqua-stat. The only time my boiler will idle is if I fill it up and my tank is completely up to temp and that is because I misjudged my use. This comes from experience that I'm hopefully getting. If it is idleing it will waste alot of heat from what I see with mine. With the big boilers it seems to be more so. I also think that with the big boilers it is more important to have cured wood because with two nozzels and alarge gasification chamber you will get more moist smoke so it is harder to get into gasification
    I cut my wood last winter-early spring and I haven't put a meter on it but I don't think it is really dry enough to get the best efficency. I think it is in the 35 to 30 range. When I have had some good dry wood I can see the difference.
    I had a owb before and I feel I'm going to use about 40% less wood but it is hard to judge as I was burning alot of different wood with the owb. I hope to do better with even dryer wood next year.
    leaddog
  8. Eric Johnson

    Eric Johnson Mod Emeritus

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    I think leaddog is right. One thing some of have tried, that worked pretty well, was to block off one of the nozzles with a firebrick or some other obstacle. Then you've essentially cut your output in half, and your boiler should run harder--and longer--with the same amount of wood. Worth a shot, anyway, especially with a two-nozzle boiler like the 60, but I think he's right about the piping. With a tank you should only idle on rare occasions.
  9. barnartist

    barnartist Minister of Fire

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    Thanks everyone. To clearify, I dont have much trouble getting my tank at full heat at 180. This tank water is basically return water from all my demand areas. I have another tank I can build and am wondering if this will help me extend my time out of a load. I seem to have enough heat to fill another one I think. It seems like as long as I keep a fire from getting to low to start a new one, I have no problem keeping heat in the tank, but, if I try and stretch it out, and let the tank water get below 160, I fight to get things hot again, particularly during high demand times.
    For example, I just fired up, and my guess is that in another hour or two, I will start idling. But if I wait too long and things get a bit cold (tank down to 160) it will be a new battle.

    As I sit here and type and listen to myself, I am realizing that maybe I need to plumb my eko directly to the tank, and let all demand areas pump from the tank rather than feed strait to my demand from the eko. I am wondering if the house loop pump keeps the Laddomat from doing it's job correctly. It is in the same loop. The problem with this is if I would get behind on a fire, I might have to wait for heat.
    Anyone have a hookup like that?
  10. barnartist

    barnartist Minister of Fire

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    Also, I almost never see my back nozzle actually burn, it seems to be the front one.
  11. kuribo

    kuribo Feeling the Heat

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    Is it possible you do not have enough capacity to satisfy both your home heat loads and warm the tank at the same time in a short time period??? What is your heat load of your home?
  12. barnartist

    barnartist Minister of Fire

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    I do not have a heat load number for you, But I do know if we shower and the furnace (exchange) runs, I see the boiler temp fall. It recovers when the furnace shuts off.
  13. Eric Johnson

    Eric Johnson Mod Emeritus

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    As you describe your system, I can see a couple more places where you might be having problems. First, I think you need to put your supply water directly into the tank hx. The way I've always heard it described is: Worry about heating the tank--everything else will follow. You can put in a bypass (either manual or automated) that will allow you to bypass the tank entirely when the house heating takes priority. Or use a ball valve to try to split the flow between the house zones and the tank.

    Both nozzles should be firing. If you have a nonfunctioning nozzle, it seems to me you'll get smoke and soot accumulation in your chimney and hx tubes. You might want to take off that blower mount plate like I suggested earlier and make sure that your secondary air tubes are still in place. You also have some primary air inlets under that plate (in the upper corners) that might need adjustment. Next chance you get, put some red hot coals over that nozzle and try to get it to fire. With only one nozzle firing, you've only got half the capacity, which is a pretty serious reduction.

    Finally, when I was speccing out my 60, I learned that 1" pipe is not enough capacity to move the output of the boiler. I think that's why you're idling so much, leading to excessive wood consumption and difficulties getting enough heat out of the system at times. The 60 is a big boiler and you don't have a huge heat load, based on your description of your house and the climate where you live. Not compared to me, and my boiler is arguably oversized. I've got a 1" and a 3/4-inch line coming off my boiler. You could add another 3/4-inch line and pipe it directly into your tank. I think that might fix your problem. Doubt your wife will want to hear about the extra expense, but I think that might be it. You might want to run that by Zenon and see what he says.
  14. Nofossil

    Nofossil Moderator Emeritus

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    Do you have anything set up that lets you draw heat from your storage tank when the boiler isn't firing? As mentioned earlier, these things run better when they're going flat out. I have an EKO 25 that I'm using to heat a 3500 square foot house, DHW, and a hot tub. It burns an average of 7 hours a day, and the rest of the time I'm living off the storage tank.

    I'm in Vermont, and my wood consumption has been 3.2 cords the first year, 4.5 cords last year, and I'm on track to burn about 4.5 cords this year as well.

    I'd start by making sure that you're getting a clean burn. Should be no smoke, no odor, and clean white ash in the bottom chamber when you're done. If it's not burning clean, we can work on that.

    Once we know that you're getting a clean burn, we can try to figure out where else you could be losing heat. I agree that you're burning way more than it seems like you should.
  15. TCaldwell

    TCaldwell Minister of Fire

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    barnartist, i have a garn plus external inline storage on the supply line, the garn is 1960gal ,external storage is 2 275gal oil tanks for a total of 2510gal,once up to temp 185+ i can run off this most all day, when i added the inline storage , depending on the flow rate, i will get a rebound effect, at lower gpm that is to say the garn tank will become a homogonized mix of unused supply water that has not left the tank and cooler return water, the temp in the inline storage will reflect what left the garn, 185+. this is exagerated if you have a high demand making the return water cooler. during a extended period of no demand the temps at all locations will equalize.If i increase the system gpm this stage of events will diminish. this represents a primary storage of 4 times the size of a inline storage, both on the supply side,if i am experiencing this with a 400k+btu burn/hr boiler, i would think putting your supply into the storage and investigating the system gpm, to see if you are circulating it fast enough. the gpm will also affect the btu:s delivered to the hx, here is a formula gpm x 8.34lbm/gal x 60min/hr=lbm/hr x delta t=btu delivered
    example 13gpm x 8.34lbm/gal x 60min/hr=6505lbm/hr x 20deg =130,100btu/hr delivered to hx.
    use this formula to figure if you are covering your demand, if not another reason why oil boiler is firing. also follow the thermostat wire and check to see if it only goes to control the zone circ, and not wired to automatically fire the boiler whenever the thermostat calls
  16. barnartist

    barnartist Minister of Fire

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    This is all good stuff and I hope you guys can stick with me, it does sound like there might be improvements that can be made. I should reset my setup once more.
    From the eko( I have the Laddomat with a built in pump that I have no idea its GPM) I have 1" black pipe that splits to go to my garage loop, and my house loop. These loops are 3/4 inch pex, and their pumps run continuous. The house pump is a taco 011, a big one, it has about a 200' loop. The garage pump is a 007, its loop is about 90 feet. Both loops go into a air exchange, with the house loop also going through a flat plate DHW exchange. Its possible the flat plate slows down the flow. All of my return water goes into the bottom of my storage tank (I can by-pass the tank), and then returns to the eko.Anyone familiar with a laddomat will know that it is suppose to close and open its valves to keep things equal for the eko, now since these loop pumps ask for water all the time, they probably fight each other when water temps get cool.
    I do have alot of tar in the upper chamber, and dark color ashes with some chunks of unburned coals in the bottom. I probably take out 5-8 gallons of ashes every week from the bottom. I added spiral inserts to the rear tubes of the eko, these need cleaned about every 3 weeks.
    Again my garage furnace never kicks on, it stays nice enough in there from heat radiating from my plumbing.
    Are you able to burn such small amounts of wood by using radiant or baseboard heat? I have probably used 4 cords already and I did not start burning until halloween.

    Fellas please keep it comming with your thoughts. Remember I have another 500 gal tank I could weld up if this will improve things. I can take photos of my setup if it helps anyone.
    THANX!
  17. Eric Johnson

    Eric Johnson Mod Emeritus

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    We're not going anywhere, barnartist. Rest assured that if they're not out getting trashed on New Years Eve, some of the guys are thinking about your setup at this very moment. Maybe some pics and a piping diagram would be helpful.

    I think you may have several issues that are combining to cause the problems you report. To reiterate my previous two points, I don't think you've got enough capacity in the way of piping off the boiler, and I think you should be putting supply water into the tank, instead of the return. Maybe somebody knows what the theoretical capacity of 1" pipe is at a given temp and rate of flow. My guess is that it doesn't approach 205 Kbtu.
  18. barnartist

    barnartist Minister of Fire

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    No trash here, pizza hut, tap water, kids in bed thanks to wife, and back to study what you guys said. Exciting ay? I will get some photos in the morning, how can I load them to the forum? So glad I found this place.
    I am willing to drive to see somebodys setup to get it right this time. I have had it plumbed every way possible in the past. Hate to think about tearing into it again, but what ever it takes. Can someone explain their setup?
  19. heaterman

    heaterman Minister of Fire

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    Barnartist:

    It would be helpful to see some pics of your piping layout. Not to say I've spotted a major problem........it just helps me to understand what's going on a bit better. One clue for me is the amount of ash you're generating. A properly functioning gasification boiler burning 15-25% moisture wood will leave very little in the way of ash. Maybe a gallon or so in that time Think of it this way. Ash is wasted heat in the form of unburned fuel. Get a moisture meter, split a chunk and test. I'd make a WAG you're not under 30%.

    Eric:
    Flow rates for pipe (copper) that are generally accepted as "good design" are as follows:

    3/4" = 4 GPM, 1"=8 GPM 1 1/4" = 15 GPM, 1 1/2" = 23 GPM, 2" = 45 GPM.

    Given a 20* temp drop from supply to return you can figure the actual BTU's being transfered by simply multiplying the listed flow rates by 10,000. If a person uses those flow rates and designs the "load" side of the equation for that 20* drop, they will find that a 007 Taco or 15-58 Grundfos will move an enormous amount of heat.

    Black steel will flow slightly higher for a given size and pex nearly the same, especially when you account for fitting loss with the copper.

    I see many systems, not just wood fueled, that are handicapped by the ("This oughta' do it") design method. Piping design isn't rocket science but there are rules to be followed as in any other endeavor.
  20. barnartist

    barnartist Minister of Fire

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    Heaterman, I will snap some pics as I load this morning. If you can check in again a bit after 10 I will try and have them here.
  21. barnartist

    barnartist Minister of Fire

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    I took many pics, I am loading them now. I will put the link here where they can be found
  22. Nofossil

    Nofossil Moderator Emeritus

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    I'm not too worried about the pumps fighting each other. I'm just trying to figure out whether you're losing heat somewhere, or whether you just have a big enough heat load so that you need to burn that much wood.

    The top chamber gets lots of creosote. If you look through the bypass damper into the stovepipe, you should not see any creosote in the stovepipe at all. Mine is just light gray ash.

    Some questions:

    Is your flue gas clear and odorless coming out of the chimney?

    Can you get return temps from each loop at a known supply temp?

    Do you have a way to dra heat from the storage tank?
  23. barnartist

    barnartist Minister of Fire

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    OK, I have pictures of my system located on my web page, www.barnartist.com In the lower right corner, there is a link W.S. click it and that should get you there.

    I'll wait for everyones comments... hit me fellas.
  24. barnartist

    barnartist Minister of Fire

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    I don't have a way at the moment to draw heat directly from storage, it must go through the eko's plumbing. My flu has a brown ash, probably because I idle alot and only burn hard for about 3-4 hours.
  25. Eric Johnson

    Eric Johnson Mod Emeritus

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    Thanks for posting those pics, barnartist. Looks like you have a neat business there.

    I'm not the best one to comment on piping schemes or storage tanks, so hopefully some of the other guys will take a look at your pics and share their observations.

    But I can comment on the boiler itself, which looks like it spends a lot of time idling. Ideally, you don't want a gasifier to idle at all, mostly for reasons of efficiency, but also to simplify boiler maintenance. It looks like you get a lot of smoke puffing back through the blowers, and presumably coating the hx tubes and chimney with soot and maybe even some creosote.

    So I think you'll solve most of your wood consumption problem if you can figure out a better way to use the tank. I just think you have it piped wrong. Even if your piping into the house is too small for the output of the boiler, with the tank right there, you should be able to use the boiler to heat the tank, and then draw all your hot water from it, as needed. Since your house doesn't use 205 kbtu/hour, the 1-inch line should be plenty. That's a pressurized tank, right?

    Ideally, you could fill the boiler up in the morning and run a load or two through it hard, dumping most or all of the heat into the tank. Then you let the boiler go out and live off the heat in the tank all day. Repeat the process in the evening, and you've got your daily heating cycle down. That's the way your system should work. And you'll be running your boiler the way it was designed to run, and undoubtedly burn less wood in the process. I think adding that other tank is a good idea with a 60KW boiler.

    Unlike me, however, Heaterman has the advantage of actually knowing what he's talking about. So I'd wait to see what he says before drawing any firm conclusions.

    So I would suggest running a bigger--or additional--line from the boiler to the tank and set it up so that supply water is pumped into the tank. Then hook up your plumbing to the house to the tank so that when there's a call for heat, your main pump kicks on and delivers hot water from the top of the tank into the heat exchanger at your house. The boiler heats the tank; the tank heats your house. Once you get it all set up right, you'll quickly learn the best way to fire it.
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