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Creosote buildup in firebox of Gassifier

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by JayDogg, Jan 15, 2010.

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  1. JayDogg

    JayDogg Member

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    I have a tarm solo 40 and burned roughly 3 cords so far this year (first year using it) My wood supply I would say is decent, It has been cut and stacked for almost 2 years, some of the bigger pieces were just split this fall though. I have a fair amount of tar like creosote buildup inside the firebox, and on the door, is this normal? Some mornings the door is slightly stuck when I pull it open. I think it is becuase i put a little too much wood in it at night so in the morning I can just put more wood in with enough coals to get it going again. Is this bad for the boiler and will I need to get that creosote off everything come spring time?

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  2. taxidermist

    taxidermist Minister of Fire

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    If your boiler idles you will have build up in your boiler. Also depends on the moisture of your wood, you say your wood has been cut and stacked for 2 years great for some types of wood but not enough for others. My red oak has been cut and split for 2 years and when I split it again to check the moisture it is 35%+,
    when on the outside it is 15%. Not that it wont burn but you get build up.


    Rob
  3. JayDogg

    JayDogg Member

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    Is that buildup in the firebox bad for the boiler? It does flake off eventually on the walls and top of the firebox.
  4. twitch

    twitch Member

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    I think the general concensus is that it is normal to get a coating of creosote in the upper chamber. I have some in my tarm, and it doesn't get very thick. It seems to burn some off, but I always have it. If you are getting like a half inch, that may be of concern, but as long as the secondary burn chamber and the heat exchange tubes are free of creosote, I don't think it will hurt the boiler.
  5. JayDogg

    JayDogg Member

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    Scott, I see in your pics that you have the gauges on the front of the boiler. Is one of them for the flue gas temp? My unit has them but they are digital and the flue gas never really gets above the 300 mark. But ive been told if i put a probe thermometer in the flue I will see temps up near 400-500. Do you have a probe in your flue? If so have you ever checked the differences between the probe temp and the temp readout on the front of the boiler?
  6. twitch

    twitch Member

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    JayDogg, My guages are for boiler temp, and pressure. Mine didn't come with the flue temp guage. I am using a probe type thermometer and I typically get 400 - 600 degrees during a burn. I'm not sure where your sensor is for the digital thermometer, but if it is not directly in the flue gas, say next to the smoke box it would probably act like a magnetic flue temp thermometer. Those types I've read here read about half that of a probe type.

    Flue temps will by lower if you have turbulators.

    I'd say that as long as you are getting good gasification and no creosote in the heat exchange tubes or chimney, then you are good to go.
  7. JayDogg

    JayDogg Member

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    Yes, the guys at Tarm told me the sensor is located in the corner of the smoke box before it leaves the boiler. I would think that they wouldve been able to get in a more accurate location but who knows. I will get a probe therm but just havent gotten around to it yet. I was trying to find a remote one that I could keep the readout upstairs so I dont have to go down and look it at.
  8. Singed Eyebrows

    Singed Eyebrows New Member

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    Are you running an inlet mixer to keep returning water temps up? It appears you are running very little storage. If running no storage & no mixer & idling quite a bit this is about as bad as it gets for boiler life. Your flue gas temps sound good & this helps. When you load wood at different times take a stick & scrape the sides of the upper chamber walls to check the creosote. The more liquid the creosote the more damage it will do as I have read. Good luck, Randy
  9. JayDogg

    JayDogg Member

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    I have termovar which is a mixing valve, so yes return temps should be ok. I do not have storage hooked up as of yet. I have been looking into it but its a little too much $$$ at the moment since I just finished building the house in August and have to get back on my feet. There isnt a huge amount of creosote buildup, just a glazing that covers the surface. But it does flake off and fall in and burn up. I have never seen any creosote in the lower chamber or on the hx tubes.
  10. webie

    webie Minister of Fire

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    JayDogg , don't worry your boiler is operating normally .
    If you didn't get a build up in your loading chamber I would worry , Its a smoke chamber the cooler water jacket will cause the smoke to condense on it forming creosote , this is normal . If you have an excessive amount , a large build up or if it starts to look more wet or even that you get tar like juice running down or out your doors ( Then you have a problem ) . Your door may get sticky from time to time don't worry again ............ If it gets too sticky or stuck shut then you have a problem . Right now I would say you are very normal .
    I have had my tarm for 8 years now , If yours isn't normal then mine hasn't been for 8 years ( OH MY )
  11. Eric Johnson

    Eric Johnson Mod Emeritus

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    Creosote in the upper chamber is normal. That's kind of the whole point of gasification. I've never understood, however, why creosote in your chimney can take off like a blow torch, but creosote in the firebox (any firebox I've every owned) won't burn even if you put a torch to it. What am I missing? It would be nice to be able to burn it off periodically.
  12. Singed Eyebrows

    Singed Eyebrows New Member

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    Hi Jaydog; I do not know how well the Termovar mixer you have works. It appears you do not have the loading unit with the built in pump that has thermometers. I would put a thermometer at the boiler inlet to be sure you have proper inlet temps. With a good hot boiler & decent flue gas temps you should be ok. My Atmos requires 80c to 90c operating temperature, although this is with the built in top probe thermometer, inlet can't fall below about 70c though. What are your flue gas temps when you stoke it up to go through the night? Atmos says that no matter what the boiler temp is if flue gas temps are too low you will have corrosion & reduced boiler life, Randy
  13. JayDogg

    JayDogg Member

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    Yea I dont have any gauges telling me the return water temps. How could I put a sensor to tell me that? i would have to tap something in on the copper line?
  14. Singed Eyebrows

    Singed Eyebrows New Member

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    If you have just copper pipe the easiest would be to buy an inexpensive infrared thermometer & just point & readout temp. Im not sure if the reading might be a little low as even copper might block some heat. If you have iron pipe I would just drill & tap a fitting & put in a therm. Then at least you have one of the variables out of the way, Randy
  15. webie

    webie Minister of Fire

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    JayDogg couple of cooking meat thermometers and some pipe insulation work too, give you a pretty good idea of piping temps heck i think I got about ten of them stuck in various places now , only cost a few bucks each and they work pretty good
  16. Eric Johnson

    Eric Johnson Mod Emeritus

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    I like meat thermometers. Great bang for the buck, and they look pretty cool, too. It's one of the few plumbing/heating accessories you can buy at the grocery store.
  17. JayDogg

    JayDogg Member

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    How would I go about tapping in a meat thermometer into copper pipe?
  18. webie

    webie Minister of Fire

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    duck tape to the out side and a little pipe insulation over the top and you are good to go
  19. Singed Eyebrows

    Singed Eyebrows New Member

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    You wouldn't! Wrap the stem with insulation against the tubing & you have a cheaper way to go than my suggestion, Randy Webie is faster than I am,reply meant for Jaydogg.
  20. Eric Johnson

    Eric Johnson Mod Emeritus

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    This.

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  21. JayDogg

    JayDogg Member

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    I wouldnt think that would give a very accurate reading though would it? I mean all your really getting is the temperature of the outside of the copper.
  22. webie

    webie Minister of Fire

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    I have one right next to one that is plumbed in and it is reading within 2 degrees , thats close enough for me .
    But then if you got the time and the bucks hey get some plumbed in , this is cheap easy and in a half hour from now working .
  23. jebatty

    jebatty Minister of Fire

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    I like the "milk frothing thermometers" available on ebay - bigger dial (1-3/4"), temperature range (30-200F) fits a boiler better than a meat thermometer, good price ($5-7 each). I use cable ties to fix the stem to the pipe, then wrap with insulation. Easy to move or remove with cable ties and no tape glue stuck to your pipe.

    EDIT: Temperature range is 30-220F.
  24. Eric Johnson

    Eric Johnson Mod Emeritus

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    I've found them to be quite accurate. Don't know why. Must be different than a stove pipe.

    The milk thermos sound good. The bigger the dial, the better. Ain't none of us getting any younger.
  25. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    One thing I will say for the GW ( I assume this holds true for all the refractory-mass natural draft units) is that the primary combustion chamber does NOT accumulate creosote. Since it is refractory material and has no water behind it to cool it, the walls remain way too hot for creosote to form and remain. Sometimes when the box has been overloaded and the damper has been closed for a while, the walls of the box will be black, almost like a layer of soot. But after the damper opens and the fire rips, the walls burn completely off.

    Jimbo
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