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Garn Boiler Feedback Please

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by woodlady, Oct 14, 2007.

  1. EricV

    EricV Feeling the Heat

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    Did you make a set of plans or drawings you can share?

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  2. brad068

    brad068 Feeling the Heat

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    My plans and drawings are in my head. I can usually build something by just looking at it or see it in operation. Always trying to make it better. After all that is the whole point. I hope my pictures come through.
  3. heaterman

    heaterman Minister of Fire

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    Here's some hard real world data from a Garn 2000 we just finished installing for a customer today. We are heating his house, domestic hot water, the garage, the work shop, his shop office AND the chicken coop. The total sq ft is over 5,500 but the garage, chicken coop and work shop are kept at 45-50* so the actual load is somewhat less than a normal structure that size.

    We've sold a few of these now and I'm impressed with them to say the least. Logistically, they are much more complicated to install than a typical OWB due to the need for assembling your own structure. I must say though that in my humble opinion the Garn is well worth the effort if converting wood to energy efficiently and cleanly is your goal.

    When we fired the unit up today the water temp was in the high 40's which is a guarantee of copious amounts of condensation. You could have filled a 5 gallon bucket with the water running out of the horizontal flue. After things settled down (water temp above 120 and flue temp above 230) I ran a combustion test with my flue gas analyzer to see what was actually going on. The numbers are fantastic efficiency wise. As you can see from the following numbers,efficiency drops a bit as water temperature rises but I have to say that many supposedly high efficiency type gas furnaces don't achieve these levels. The first number listed is the water temp and the second is the corresponding combustion efficiency.

    120* 90.7%
    130* 89.5%
    140* 87.6%
    150* 85.3%
    160* 85.1%
    170* 84.7%
    180* 84.4%

    Any efficiency above 87-88% is basically in condensing territory and the Garn is not designed to operate in that range. In fact, the only alternative fuel boilers that do run in this range, are available only in Europe.

    Carbon Monoxide production is severe but less than half of what I see when I test a typical "ice shanty type" OWB. CO ran as high as 2,800ppm at fire up but as the burn continued dropped dramatically to in the 400-500PPM range. Numbers over 5,000ppm are standard for the normal OWB and that's a full burn. Idling is off the chart and would ruin my meter if left in the flue.

    I met a customer this fall that has a Garn in operation that he bought 23 years ago. No problems except a draft motor. That is a track record few if any OWB's will ever reach. If a Garn looks good to you, don't hesitate to buy one.
  4. TCaldwell

    TCaldwell Minister of Fire

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    heaterman, garnification, this information to me is music to my ears, maybe we can change the world , 1 garn at a time! where did you get the combustion gas analyzer, how many have you installed, my experiences are near the beginning of the thread, garnification i cant find the pics.
  5. brad068

    brad068 Feeling the Heat

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    Heaterman you have seen the light too! These boilers, in my opinion are the king. I built mine to break up the last flue to transfer more heat with more surface area. I had to recap the bottom of the WHS-500 boiler that I picked up and after that I got it running and did some testing on it. I found that by sticking a 4" probe style analog temp gauge in the exhaust right out of the boiler the temp ran at 350-400 degrees F. There is alot of heat there yet so with my units design it runs at 220-240 degrees F out of the boiler. I sent pictures to this website but I can't find them. Also I don't think people understand how powerful these things burn. I would say that my is moving 500-600 cfms. That is alot of air with alot of heat in it. The movie at Garn home doesn't do justice for these units. They are awesome!!
  6. TCaldwell

    TCaldwell Minister of Fire

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    garnification, does the bundled tube last pass hx go from the front to back or just part of the distance, i toyed with the thought of a series of radial strap on heat sinks on the exhaust tubes. did you notice any more or less puffing with your modifications?
  7. brad068

    brad068 Feeling the Heat

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    It goes the full lenght of the boiler. It still puffs but my door latch design locks the door both ways so it can suck in or puff out. with the door latched you can't even tell my furance is burning. Did you see my pictures on here?
  8. TCaldwell

    TCaldwell Minister of Fire

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    garnification, where should i look to retrieve the pics?
  9. heaterman

    heaterman Minister of Fire

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    TCaldwell

    I sell Testo equipment which is a German made line of testing equipment made for professional use. A combustion analyzer like the ones we use costs from $1,200- $1,600. It tests O2, CO2, CO, temperature, excess air, flue pressure +/-, and CO ambient I don't see how most HVAC guys get along without one.

    I've only sold Garn for about a year and this was our third installation. I wouldn't go as far as to call them smokeless but they burn much more cleanly than anything but another gasification appliance. The build quality is second to none.

    Another unit I really like is the Econo-Burn gasifier. Relatively new but they are modeled after the best units made in Europe, Austria to be specific. They will be ASME rated very soon and carry the listings to be installed as a sealed system in any jurisdiction
    They weigh about 10-15% more than other similar gasification units (EKO and others like it). We'll be installing our first one of those in about 3 weeks and I'll see if I can post a report here.
  10. brad068

    brad068 Feeling the Heat

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    I wonder if any of the downdraft gasifying units will make 15-20 years on the nozzle? The older Garns that I've seen in use(20 years +), the ceramic in the second burn chamber is still original. The fire bricks in the bottom can be bought anywhere along with the draft motor. No fancy microprocessors, no high tech nozzle or secondary burn chamber and the best geometric building shape, round. Round door, round flues. Equal expansion in a circle-no cracks in the corners along with two sided welding.

    I got my ceramics from Unifrax. The door is comprised of a 20" and 22" tank ends one turned inside the other. The draft motor is a 56C frame 3/4 hp 3450 motor with a homemade 9" 8 blade fan wheel. The water vessel is a 1500 gallon milk tank with a 1"x 1" drilled and tapped ring 54" I.D. welded to one end of the tank. The front plate with the firebox and flues welded to it slide in the one end and gets bolted to the tank. I have a manway access into the tank or I can completely remove the "guts" of the boiler if I so choose. I monitor burn temps with three 200-1000 degree thermometers. One in the lower cleanout/inspection cover, one in the fan chamber, and one in the flue pipe exiting the boiler. The first gauge (which is 15' away from the secondary burn chamber, following the exhaust flue) will bury the needle and then level off @ 975. The second one will run @ 400. and the third will stay between 220-240. I think that my final exhaust is to cold though, it will steam like a high efficiency gas furnace through most of the burn. But I can raise @1300 gallons of water more than 40 degrees in one hour.
  11. TCaldwell

    TCaldwell Minister of Fire

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    heaterman, thanks for the analyzer info, do you sell one that is permanently mounted or data logger capable, i have a garn model 1900 ractangular. I installed a thermocouple at the rear of the secondary burn chamber sticking up and centered on the exhaust tube, average high temps 1700-1900f with a high of 2170f, last pass out temps seem to run 2.5 to 3 times less, dependant on boiler water temp garnification, your burn chambers and air box are gasketed and bolted to cut outs in the tank end, totally removable guts, very inovative. In my unit the secondary burn chamber is stepped up about 3 inches above the fiberfrax of the primary chamber, are the older units the same, also i heard of bundled tubes right behind the secondary chamber, mine is one 4.5 inch tube. thanks for the info.
  12. webbie

    webbie Seasoned Moderator Staff Member

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    Pictures are uploaded - see other thread on this forum.
  13. heaterman

    heaterman Minister of Fire

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  14. cupcake

    cupcake New Member

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    Garnifacation. It takes you that long to raise the temperature 40 degrees :question: :roll:
  15. heaterman

    heaterman Minister of Fire

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    FYI Some more Garn data for those interested;

    Here is the calculated actual OUTPUT rating for the Garn we installed this week and it's pretty impressive. Right on with the factory spec of 400,000 btu/hour burn rate. At start up the water temperature was 45*. Exactly 6 hours later, the 2,000 gallons(factory rated capacity) of water stood at 186* soooooo.......

    2000 x 8.33 = 16,660 (total gallons x weight /gallon= total weight of water

    16,660 x 141 =2,340,600 btu's transfered (pounds of water x temp rise = total btu's)

    2,340,600 / 6 = 390,100 (total btu's divided by elapsed time in hours = btu/hour)

    You can deduce from those numbers that the factory burn rate is fairly conservative. This is due to the fact that if the burn rate is actually 400K per hour and the unit transfered 390K, the efficiency would be about 97-98%. Obviously that number is unattainable because it is way past the condensation point of the flue gas. This happened early in the burn but then ceased when water temps got into normal operating range. These numbers substantiate the flue gas measurements for efficiency I was getting with the analyzer.
  16. brad068

    brad068 Feeling the Heat

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    High E, Is that HI Everyone or does that refer to some sort of boiler unit?
  17. cupcake

    cupcake New Member

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    garnifacation,to your question about name.Yes it is High Efficiency Stoves. I'm currently burning my 2nd home built high efficiency stove. Could you answer my water temperature questiion. I have rasied my water storage temperature 40 degrees in 45 min. And that is a 1900 gal tank. ;-)
  18. Eric Johnson

    Eric Johnson Mod Emeritus

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    Alright, two guys from Central Wisconsin. I'm from Coloma originally. Where are you guys doing all this fabulous fabrication?
  19. leaddog

    leaddog Minister of Fire

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    Quote(I have rasied my water storage temperature 40 degrees in 45 min. And that is a 1900 gal tank.)


    That must be a large boiler as by my calulations I come up with over 800,000btus an hr.And I thought my eko80 was large.

    garnifcation---- That is a very impressive boiler and the workmanship looks outstanding. You must have a good scrap supply of stainless or else you would have more that the cost of a new garn. Your shop is very impressive also. Are you a fabricator by trade?
    leaddog
  20. brad068

    brad068 Feeling the Heat

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    leaddog, My tank is a 1500 gal milk bulk tank that I picked up at a dairy supply dealer. My figures is that my water storage is only @1300 gal figuring firebox and flue displacement. As I stated before I broke up the last flue pass into 9 2" pipes to strip more heat out of the exhaust gas. The secondary burn chamber on my unit will glow bright orange must be at least 2000 degrees and my final temp probe has not exceeded 240 degrees. I am a fabricator by trade.
  21. brad068

    brad068 Feeling the Heat

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    I have seen High E's boiler and it does work well. Although he is still using his fingers and toes to do his calculations I do suspect that his boiler can do what he says!
  22. TCaldwell

    TCaldwell Minister of Fire

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    high e , what do you have under the hood, do you have any pictures? it almost sounds like garn 3200 burn chambers in a 1900 can. heaterman thanks for the testo info, a couple of burners in the hood and i might consider. also it is nice to see field data , always nice to validate, thanks
  23. brad068

    brad068 Feeling the Heat

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    TCaldwell,

    Do you have a thermometer in/around the fan housing?
    If you do, what is the temp at full burn.
  24. TCaldwell

    TCaldwell Minister of Fire

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    garnification, full burn temps ave 450 if lucky 550 and once 600
  25. brad068

    brad068 Feeling the Heat

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    Hi E was in my shop today. I think he has finally figured out how to build the flux capacitor. He is the only gasifier I know that can heat his water storage with a box of toothpicks; the 800 count family size of course.

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