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What kind of stack temps do you have at full output?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by BoilerMan, Oct 14, 2012.

  1. JP11

    JP11 Minister of Fire

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    Ok.. could be a dumb statement..

    but could the fan be wired for 220?

    You've got half the "legs" of power and half the fan speed?

    Note.. I did NOT stay at a holiday inn express last night. I'm sitting in bed at a doubletree!

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  2. rkusek

    rkusek Minister of Fire

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    220v 50Hz motor should run 20% faster at 220V 60Hz but otherwise be fine from my understanding. Doing the opposite is where you run into problems I believe. Taylor are you using a 220V plug right out of your mains or some kind of step up transformer?
  3. The suction fan set up is similar to my biomass. When it was new the set screw on the fan blades was loose so the fan was not turning at full speed. It didn't gassify well untill I got the fan running right.

    So are you sure the fan is spinning freely and at full speed?

    On my biomass I dont open the bypass when starting a new fire. I turn on the suction fan and light some cardboard and small splits, the suction fan is strong enough to pull the smoke through the lower chamber with the upper chamber door partially open. I have an almost instant gassification flame while the cardboard burns off.

    I would assume your boiler should be similar in operation if the fan is working as designed.
  4. BoilerMan

    BoilerMan Minister of Fire

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    Ok, a lot of questions here. Fan came with a Swedish 115V 60Hz motor, as well as the controller 115V 60Hz. Fan motor had to be taken out and some machine work done on the shaft though. Long story, the shaft was 1/4" too short from the factory,:confused: so I took it to my favorite machine shop and they welded on a short piece to the end of the shaft and machined it true, you'd never know the difference looking at it now. The fan was hitting the motor plate, no way around it, someone must have been sleeping on the assembly line. This mod to the shaft in no way has any bearing on CFM befor or after, just mechanical room. Anyhow, everything on that end is good as far as I know. Fan works well, pulls smoke into the lower chamber easily and is very easy to start a fire, with quick rumbeling noises from the lower chamber. After the door is shut though, I don't know what is going on. Can't peek at the secondary flame, and it's very quiet outside the unit other than the fan noise, no rumbeling. I have no baseline so I don't know what is normal. I want a window to see into the lower chamber during a burn, than the truth will be out! Should have bought a Varm, as it was my first choice........

    TS
  5. BoilerMan

    BoilerMan Minister of Fire

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    Mike, how do you know if your getting a good secondary burn (or any secondary)? My boiler sounds just the same as far as lighting a new fire, keep the bypass closed, rake some charcoal over the nozzle, with two small splits over it, turn on fan, propane torch for about 30sec. Done, rumbeling from lower chamber in leff than a minute. It's after that, that I don't know about.

    TS
  6. Mine has a viewing port on the lower door. You can't really get a good view of the flame but you can tell its gassifying by the orange glow. I can open the lower door slowly and see the condition of the flame. With both doors closed I can't hear if it's gassifying or not.

    On mine the secondaries are barely open. If I set them too far open than it blows out the secondary flame. To find the sweet spot I got a good bed of coals threw in some splits and adjusted the secondary air inlet while I watched the viewing port. I closed the air inlet down untill the flame went out and then adjusted the other way untill too much air blew out the flame. And set the air in the middle. For me it's set at about 15-20 % open.

    Another thought - on my nozzle there is a front and back. There seems to be an air path molded into the front of the nozzle that goes from the air inlet to the lower chamber. It's subtle and would be easy to put in backwards. Not sure what would happen if it was put in backwards.
  7. mr.fixit

    mr.fixit Member

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    Is there anywhere on the boiler,like a access panel or clean out cover,that may not be sealing properly,letting the fan suck in air where it's not suppose to? Just a thought.

    Is it possible that the fan may be turning the wrong direction? Some motors are reversible so you never know.
    Could of been wired wrong if it is reversible.If it's a non reversible motor,never mind.
  8. Gasifier

    Gasifier Minister of Fire

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    Taylor. What's the latest?
  9. BoilerMan

    BoilerMan Minister of Fire

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    Zenon from NH is getting ahold of me Monday. Fas is going in the right direction (unidirectional motor). All sealed up, I gave it a good inspection before filling and fireing the system. This does look to be a vell made unit, welds look top notch, and overall good fabrication work. It's just getting it to perform as intended is the big hangup. As of now it's in the 50s outside and I've had a couple of fires in the LR stove which will heat the house until it's sub-zero. I just want it to not glaze up my flue, I'm under the impression that once I get good secondary burn all the glaze will burn off in the lower chamber, the chimney top is another question. I'll keep you posted. Any other ideas are welcome, and thanks to all who have posted and made suggestions!

    TS
  10. BoilerMan

    BoilerMan Minister of Fire

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    Mikefrommaine, you may have solved the problem! I richened the air/fuel mixture, (closed) the secondary air a bit when I could hear the rumble, and it got louder! The factory setting mark is about 33% open, now it's15-20% I saw stack temps around 275F still, but they were sustained for almost two hours and Zero Smoke!!! This thing puts out some heat, charger my 115gal indirect from 105 to 175 and had to dump quite a bit of heat in the floor. The reason I fired it was to charge the indirect so I didn't need to fire the toyotomi for a shower in the morning. Anyhow, things are looking up, I was thinking the fire needed more air, it is always my motto to let more air in if the stack is low, but not this time. I still think my stack is low, but it burned well, and some of the tar-glazeing in the lower chaimber exaporated/burned off. Thanks all for your input! Buyers remorse now gone:) Now that I have some type of baseline, I can work from here.


    TS ​
    lotawood likes this.
  11. Gasifier

    Gasifier Minister of Fire

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    !!! Yaaa! Good to here Taylor. Now you are going to see what that baby can do! Keep us up to date. Pics! We like pics!
  12. Glad to here its working for you. :)
  13. Eric Johnson

    Eric Johnson Mod Emeritus

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    Great news. Enjoy!
  14. kopeck

    kopeck Minister of Fire

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    For what it's worth my Tarm runs nothing close to the factor "initial settings".

    Very cool to hear things are looking up.

    K
  15. JP11

    JP11 Minister of Fire

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    Ditto

    Now that you're in the ballpark.. it's just tweaking. HUH.. for once it wasn't wet wood!

    :)
  16. BoilerMan

    BoilerMan Minister of Fire

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    Well I was hopeing I kinda had the wood thing down........ LOL, the nerd in me with a Moisture Meter and all. Sometimes I don't know how my wife puts up with me. I know I was getting some gasification before due to the cleanlyness of the refractory, it's just the long term burn that was not good, you guys with your oxygen sensors.... For us poor folk, we are the lambda control, it's just takes us a bit longer to get into "closed loop".

    TS
  17. JP11

    JP11 Minister of Fire

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    Best tax return money I ever spent. Fill 'er up.. Hit the button. Tanks were 131 when I got home. 30 mins later.. 147 and climbing fast. Glad you aren't having buyers remorse anymore. Now it's just getting to the flat part of that learning curve.
  18. BoilerMan

    BoilerMan Minister of Fire

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    Haha, I'm self employed, I try not to pay taxes, so no returns. LOL, I wish I could make my house worth less....well to the town anyway.

    TS
  19. JP11

    JP11 Minister of Fire

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    I know just where you are coming from. My wife is a self employed photographer. A big portion of our house is her photo studio. I tell her not to look at the tax returns.. that's not what she is "making"

    I wanna puke when I see how much Maine takes from me every year. I'm out of state so much for my job.. with a little documentation.. and a couple extra vacations out of state.. I could claim residency elsewhere.
  20. woodsmaster

    woodsmaster Minister of Fire

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    I'm a little late in the thread but I was going to say if you shut the door and don't hear a rummble the air settings are off. My biomass looks set up similer to your attack. When I clean the tubes I get around 325 F stack temps and as it gets dirty It rises. After about 6 - 9 months temp get up to about 500 and then I clean it again. If you change to different wood or moisture content youmay have to change the air settings again. That's where a lambada boiler would be nice.
  21. heaterman

    heaterman Minister of Fire

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    Stack temp at full output?........Depends on how much hot sauce was on the tacos..........._g
  22. heaterman

    heaterman Minister of Fire

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    Taylor I didn't take time to read through this whole thing but downdraft gassers need 3 things to burn correctly. Dry wood, the correct chimney draft, correct air flow to the fuel and dry wood........oh, I said that already..... So back to the three....

    Dry wood. I have never been able to get good secondary combustion out of any brand/type of gasser with wood over 25% moisture content. The phase change converting liquid in the wood to vapor in the flue just steals too much heat from the combustion process. If your wood is over 25% you're just going to have to suffer through it until your wood pile gets to where it needs to be.

    Chimney draft. This is critical to getting the flue gas up and out of the secondary combustion chamber. The exhaust fan in most cases is there to ensure things move through the interior of the boiler in good fashion and at the right velocity. It's not really intended to actually exhaust the flue gas and create a positive pressure in the chimney like a Garn does. If the chimney doesn't draft things tend to get constipated.

    Correct air fuel mix. Most of the gassers I have seen that have been set up by the owners have too much air going through them. A lot of excess air can cool your flue gas too much and will also mess with secondary combustion. The only way you can really dial this in is with a combustion analyzer but you can get close by playing with the air shutter/fan speed and just observing. I would try dialing the air back to about 60-70% of where ever it is right now and give it a try for a few loads. Then adjust accordingly.

    Lastly, every DD gasser I have encountered has some tar buildup in the firebox to some extent or another. This is absolutely normal. The flue gas there is in direct contact with the water jacket which of course is many hundreds of degrees lower than the gasses being generated there. Firebox temp will usually be less than 1000* and this will always allow some condensation to occur. The ultra high temps of 1500* + don't happen until you hit the secondary combustion stage.
  23. BoilerMan

    BoilerMan Minister of Fire

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    Just wanted to follow up again, I've been burning only every two days for DHW production. This thing really puts out some heat! I can't dump it into my indirect fast enough. I love it, I have to use the radiant floor as the dump zone, which is perfect for the shoulder season. I can hit idle (set 195) in no time at all from a cold start with just the indirect, all this is only burning about 6 splits! My stack temps are getting into the 275F (factory exhaust probe) and staying there during the duration of the burn. I set the "FUEL" fan shutdown at 200F which gives just the right amount of charcoal to start a new burn in less than 5min. Easiest fires to start, makes a wood stove look like work! LOL Mark me down as a happy customer, it's living up to it's modern looks.

    TS
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  24. muncybob

    muncybob Minister of Fire

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    I'm finding that the type of wood has a bearing on the stack temps. In this shoulder season I am burning mostly dry willow and I'm seeing stack temps at only 250....throw some maple in there and it's closer to 300. More btu in the wood means higher stack temps, makes sense I guess.
  25. Gasifier

    Gasifier Minister of Fire

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    That's interesting that you say that muncybob. I have been burning a low BTU wood lately as well. Usually considered a "weed" tree around here. I got the wood for free last year, besides the work I put into it anyway. But that Boxelder (a soft species of Maple) is only rated at 17.9 million btus/cord. This is just under Red Maple (still a soft wood) at 18.1 million. And that as compared to Sugar Maple, a hard wood, at 24 million btus/cord. But this Boxelder is throwing good heat. Just like when I have burned it in my Pacific Energy Super 27 wood stove years past. My stack temps have been plenty high enough, unfortunately that is sometimes because I have lost gassification<> , but even with good gassification I am seeing stack temps around 400. The Boxelder is certainly not a premo wood, but with it being free, I am going to continue to take it when I can get it! The stuff I am burning now I split almost a year ago and put it under the porch way too early. Luckily I put it in the back and left it there when I realized this spring that it was not ready to burn. M.C. was still too high. But it has been great to burn the last four weeks for hot water and a very small amount of heat demand every once and a while.

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