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Yet another "I want to build a Gasser" thread

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by kabbott, Aug 30, 2009.

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  1. kabbott

    kabbott Member

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    I know that a few of you have tried this, and I will probably spend almost what I can buy an Eko 25 for minus the tax break buttttttt what fun would that be?

    I am looking for some guidance on nozzle sizing and firetube surface area.

    For an eko 25 size or similar I was thinking 8 or 9 2 inch id. tubes 40 inches long for firetubes
    The nozzle is a bit harder to tell from photos, maybe 1 x 8 inches?

    I have a good grasp on the theory and basic design, need to control primary and secondary air and so forth. What I need are few of the more critical
    dimensions. Would save a bit of cut & try.

    I do have a folder on my laptop with Nofo"s brothers pics of his boiler and they have given me many good ideas, Have studied them for a while now. :coolgrin:

    If any of you eko, tarm or econoburn owners happen to know some of the dimensions or even approximately, close or maybe that is more than what I have now.

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  2. pybyr

    pybyr Minister of Fire

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    Hmm- not to cool your enthusiasm, but the install and the rest of the system should provide you with no small amount of fun, unto itself. Are you aiming to have this in service this winter?
  3. kabbott

    kabbott Member

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    I have that "FUN" already done. But yes I know what you mean the boiler is just a fraction of the work.

    Some history to let everyone know where I am at.

    1. Started in this house with coal, was here when i bought the place. Was nice but the coal ran out and my wood is free(- me felling-cutting-splitting-stacking.....its never really free is it?)

    2 Got an old fisher stove in the basement and that was fine for basement and 1st floor, but not 2nd floor. 2nd floor was unfinished so no probs, used it for ~12 years.

    3 Kids are running me out of room so started working on 2nd floor and knew the stove wasn't gonna cut it so it became the firebox for the boiler I use now.
    Works great but uses to much wood. Then I found this forum and decided to add storage. Made it much more convenient but still very inefficient.

    So the system is ready to go plumbing wise plus ~17-1800 gals storage which should work nice with a gasifier.
  4. Nofossil

    Nofossil Moderator Emeritus

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    As you know, it can be done. You're on the right track in starting with a 'known good' nozzle design. There are a few things that you want to keep in mind:

    1) It's critical to be able to tune primary and secondary flow rates. Both the total flow and the ratio are important, and both change over the course of a fire. A wideband lambda sensor would be a help in setting it up, but there's no 'howto' available.

    2) Starting fires is a problem worth thinking about. The conventional approach is to have a bypass damper so that you start the fire in updraft mode, then switch over. There are lots of variations and alternatives.

    3) Materials will be a challenge. It's hard to get refractory materials that will stand up to the physical shock, temperatures, and temperature gradients.

    4) Differential thermal expansion is not your friend. The metal portions of the boiler can warp because one section may be near 1000 degrees while another nearby is at 180.

    5) You have to protect the secondary combustion zone from any contact with the water jacket. A long and turbulent flame path is good.

    6) Once combustion is complete, lots of easily cleanable HX is good - just think about how to avoid flue condensation.

    As I've said before, with gasifiers there's a lot of technology lurking in a deceptively simple package. I wouldn't want to discourage you, but if you go ahead please be prepared for the challenges and share your experience.

    Good luck!
  5. deerefanatic

    deerefanatic Minister of Fire

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    I'll tell you from DIRECT experience, you WILL spend more money, and you probably WONT get a working unit out of this endeavor... Not trying to damper you or be negative, but that's what happened to me.....

    BUT, if you're going to take this on, here are some pointers.

    #1; YOU MUST water jacket the whole stove like EKO does.... I tried to get away not doing this to save money.... The stove warped... BAD and was ruined.

    #2; Air control is tricky.... Don't try and get creative with this.. EKO has a GOOD setup and do yourself a favor and do it as they did.

    #3; If you don't have a GOOD BIG welder (180amp or larger MIG welder with shielding gas, obviously a 220v unit) and the skills to use it properly, DONT weld this yourself.... You'll be chasing leaks forever.......
  6. kabbott

    kabbott Member

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    Sorry to hear about yours warping, I was following your progress last year and had high hopes. looks like you bought an EKO 60?
    Is the front of the EKO wetted?(the end with the doors)

    I was planning on air control adj. similar to EKO with adj pri, sec, and total air.

    The welding is one thing that wont be a problem. I have stick, mig, tig , oxy, and have experience welding pipe. It won,t leak ;-P
  7. kabbott

    kabbott Member

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    Thanks for the tips Nofo

    I have an lm1 wide band O2 sensor for tuning my car but wouldn't know where to start with a wood boiler.
    Maybe I will buy a new sensor for the gasser.Do you have one?

    Looks like your brothers is only wetted on one wall and the rest lined with fire brick. How is it holding up?
    I had intended to build something close to that but if it won't hold up? Water jacket around the whole thing wont cost me much more but
    it sure makes it more of PIA to make that's for sure.

    BTW nice NFCS forum. Will be posting on it bugging you about that before long. :cheese:
  8. Nofossil

    Nofossil Moderator Emeritus

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    I have a wideband lambda sensor but haven't installed it yet.

    My brother has had problems with cracking refractory but the unit works very well. He preheats the combustion air by passing it between the non-wetted side and the outer shell. Keeps the outer shell cooler.
  9. hdivr

    hdivr New Member

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    Are you really decided on an Eko-type gasifier? I ask only because a Seton or Greenwood type gasifier would seem much easier to build. Less welds - just firetubes in the exhaust path. The refractory is definately expensive though......

    I was considering building a seton type boiler, but I could almost buy a gasifier and have it shipped to the states for about the same price including shipping!

    Haven't decided to pull the trigger yet due to this incessant fear that "once money is sent overseas......it is gone" No way to get it back.

    But that is the risk.
  10. kabbott

    kabbott Member

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    I'm not really stuck on the eko design but it seems to be the most popular so it would take some convincing another would be better.

    If-- and this is a big IF-- I could get away with just one side wet it will be no problem as far as the metal works.
    Wetting 3 or more walls will be a PAIN and I'm not sure I would tackle that. I have the equipment and skills to do it but not sure I want that project when I could
    buy one for like 3-3500 after tax rebate
    The refractory is another story all-together, that will most likely take a few tries to get right.

    My thoughts were to make one wall wet in back, doors in front, and double wall both sides to preheat air.Maybe with some baffles in sides(to make the path longer) to try to preheat cold outside air.

    I know of the extreme temps in the secondary chamber. Anyone care to guess what temps to expect in the primary chamber? I would think
    that with air flow between the panels and fire brick on the inside that it would hold up as well as a wood stove.
  11. Nofossil

    Nofossil Moderator Emeritus

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    The primary chamber really should be no worse than a conventional woodstove.

    In the secondary chamber, give some thought to flame impingement. anything in the flame / exhaust path will get HOT. I keep a thermocouple in my exhaust path. After a labyrinth with three 90 degree bends and well after the end of the combustion zone, the gas is still 1500 degrees. That's warm, and it also means that there's about a 1000 degree temp differential across the refractory that houses the combustion itself since the combustion is around 2500 degrees.

    In my brother's he has an asymmetric labyrinth that dumps all the exhaust out the left side, where it impinges on the wet wall. There's dead air space and firebrick insulation on the other walls, and they still get scary hot (under the outer jacket). Be careful.
  12. deerefanatic

    deerefanatic Minister of Fire

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    the Eko's are wetted both sides, back, and top.... the bottom is not wetted, and the front isn't either... If I was going to make a stove, I'd make a water jacket door for the top and bottom..... Although that's patented by Taylor Outdoor stoves so don't get caught doing it.. :)
  13. Duetech

    Duetech Minister of Fire

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    Actually the EKO40 only has six 2" tubes in the heat exchanger and I believe the 25 has six as well. The 60 and 80 models have twelve according to reports I have read. The 40"s nozzle is around 9" long and the gap about 1-1 1/4" wide. I measuerd mine once but it has been a while. I wouldn't worry about patents as long as you are not going to try to sell your boiler.
    Another boiler that might garner consideration before you jump on any one design is the Econoburn. From all accounts I have read it seems to be a pretty stable unit. I think I would stick with EKO's control module though. The EKO Super, which is their current import model, has tube cleaners built right in and though I find them very helpful, as I currently run my unit without storage, I would prefer to have them in a location I could access without climbing on a ladder. Though it goes without saying use black pipe or copper for your nonflexible plumbing.
    Comments about nozzle refractory have been made and EKO supposedly has ready built replacements for their models and they are supposed to have refractory cement that you can cast if you are so inclined but it would probably be good if you have connections with someone with a pottery kiln to fire your creation. Even so there have been failures with both pre cast and home made. It's a project and I wish you the best. Additionally if you are going to house your unit in an out building that it would be good to know if you would be better of to use 1 1/4" or 1" pex and for peace of mind use O2 barrier type pex.
  14. Nofossil

    Nofossil Moderator Emeritus

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    As the Duchess of Windsor once said, "A woman can never be too rich or too thin, and a man can never have too many heat exchanger tubes". At least that's what I think she said.

    In one of my own fantasy sketches I have two wet side walls containing HX tubes. The front has an outer door that serves as part of a combustion preheat jacket.
  15. brad068

    brad068 Feeling the Heat

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    Careful with the to many HX tubes, unless you are going the condensing route then I would think about using SS.
  16. kabbott

    kabbott Member

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    Yes that could be a problem, but stack temps will always go up with use so more tube would mean less cleaning and Worst case I could block off 2 tubes much easier
    than adding 2.
    Looks like Eko 25 is 37" to flue so tubes cant be more than ~30". Me thinks 8 -- 2"ID x 40" should be close.


    Dug this old thread up for more research http://www.hearth.com/econtent/index.php/forums/viewthread/9508/P45/
  17. pybyr

    pybyr Minister of Fire

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    If you're going to build a gasification boiler from the ground up, why rely on an off-the shelf controller-- instead, why not integrate the control of the boiler's blower into the same set of controls that you use to integrate the boiler into storage and heat zones? -- I think you could probably achieve closer operational integration and higher efficiency that way.
  18. brad068

    brad068 Feeling the Heat

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    Kabott, I hope your boiler project turns out well. I too like to build my own things. I suppose a garn style is out of the question. Just from the looks of things I think a garn style boiler would be much easier to build and much more user friendly :red: ,just my opinion though.. Best of luck.
  19. kabbott

    kabbott Member

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    Thats what I'm thinking to. Failsafe to some extent with an aquastat to turn the pump on then the rest up to some variation of an NFCS.
  20. kabbott

    kabbott Member

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    The only thing about the garn is I already have storage and dont really need more.If I were building everything from scratch It would get
    serious consideration, looks much less tempermental. I seem to recall seeing some photos of yours, NICE job. :coolsmile:

    My wife already thinks i am nuts, just looking for something to build. She doesn't have to split the wood though.
  21. brad068

    brad068 Feeling the Heat

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    But what if you go with the garn style but scale it down. The first ones they built where 500 gallon units and I think you could still cut that in half or more. Use the crossdraft setup an instead of 40'+ of 4" use multi tubes like the switzer. I think the 3200 gallon unit uses a bundled hx closer to the secondary than mine.

    I think garn went the way of big storage inter-grated because they knew to burn wood in a boiler at peak eff. why not build it out of a big tank? And everyone associates the name garn with hugeness. Don't get me wrong, the current design is bulletproof, but I think the design is totally capable smaller and pressurized but make sure over temp protection is used.
  22. Nofossil

    Nofossil Moderator Emeritus

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    Of course, you could go with an off-my-shelf controller ;-)

    I hope to have the circuit boards for variable speed circ control ready for delivery in September. Next up on the software front is PID control so that you can wrap a PID loop around a temp sensor and a variable speed circ (or blower). I've done a LOT of testing and I'll be going with a modified PI loop that incorporates elements of outdoor reset for load estimation. Looks pretty effective and stable.
  23. sdrobertson

    sdrobertson Minister of Fire

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    Hey Garnification....I really like this idea of a smaller Garn style boiler that you could hook up to additional pressurized storage. This would be the best of both worlds as it would be easy to customise it to fit your exact situation.
  24. pybyr

    pybyr Minister of Fire

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    Indeed- much what I was thinking of, though I didn't know for sure (though I am not surprised) whether the NFCS could manage the boiler's blower, too. My point was simply why go with something like the EKO type control (while I am sure it works fine well, it has to be configured to run a boiler somewhat independent of specific system parameters, and thus needs to be oblivious to what's going on beyond the boiler) when something like the NFCS could make it all seamless. The NFCS is definitely the apparent 'killer app' for alt-heat.
  25. fabguy01

    fabguy01 New Member

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    What do you mean by "crossdraft"? What about a garn style out of a 500 gal lp tank? between the firebox and HX you would be down to 250 gal of water. Wait a minute I need to go measure my tank im thinking my next project became much more clear. P.S. garnification did you just buy the reaction chamber from GARN or did you make it?
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