# Creosote buildup in firebox of Gassifier



## JayDogg (Jan 15, 2010)

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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## taxidermist (Jan 15, 2010)

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


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## JayDogg (Jan 15, 2010)

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


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## twitch (Jan 15, 2010)

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.


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## JayDogg (Jan 15, 2010)

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?


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## twitch (Jan 15, 2010)

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.


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## JayDogg (Jan 15, 2010)

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.


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## Singed Eyebrows (Jan 15, 2010)

JayDogg said:
			
		

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


 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


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## JayDogg (Jan 15, 2010)

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.


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## webie (Jan 15, 2010)

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 )


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## Eric Johnson (Jan 15, 2010)

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.


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## Singed Eyebrows (Jan 15, 2010)

JayDogg said:
			
		

> 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.


 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


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## JayDogg (Jan 15, 2010)

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?


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## Singed Eyebrows (Jan 15, 2010)

JayDogg said:
			
		

> 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?


 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


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## webie (Jan 15, 2010)

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


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## Eric Johnson (Jan 15, 2010)

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.


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## JayDogg (Jan 15, 2010)

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


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## webie (Jan 15, 2010)

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


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## Singed Eyebrows (Jan 15, 2010)

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.


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## Eric Johnson (Jan 15, 2010)

webie said:
			
		

> duck tape to the out side  and a  little pipe insulation over the top and you are good to go



This.


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## JayDogg (Jan 15, 2010)

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.


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## webie (Jan 15, 2010)

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 .


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## jebatty (Jan 15, 2010)

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.


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## Eric Johnson (Jan 15, 2010)

JayDogg said:
			
		

> 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.



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.


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## ISeeDeadBTUs (Jan 15, 2010)

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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## ihookem (Jan 15, 2010)

Just a thought. Can I use a cooking thermometer to check my flue temps. I guess I could drill a 1/8 " hole in the stack and just put it in. Does anyone do this. Also, I've been thinking of getting some fire brick to put on the bottom of my Eko 25 to help retain heat. Does anyone add fire brick on the bottom where it gassifies? Also I was wondering if I could try to stack fire brick on the side walls of the fire box. I thought if I can keep the brick  tight against the side walls it might keep creosote off the walls, make it last longer and maybe keep it hotter. Would this work?


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## twitch (Jan 15, 2010)

If you could find a cooking thermometer that would take up to 1000 degrees F, I suppose it would work.  I don't think I'd put firebrick in the firebox due to creosote getting between it and the steel.  I seem to remember some OWB (I think) that had problems when the manufacturer started putting them in, and then were telling people to remove them.  I'm just not sure how you could keep them tight enough to the wall to avoid creosote getting behind them.


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## Eric Johnson (Jan 15, 2010)

I think BrotherBart once suggested using a barbecue thermo for measuring internal stack temps.


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## pybyr (Jan 15, 2010)

JayDogg said:
			
		

> 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.



Copper is an excellent conductor of temperature-- put insulation over the outside, and the metal should be virtually the same as the water.  After all, most "sensor wells" are brass, copper, etc.


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## jebatty (Jan 15, 2010)

ihookem said:
			
		

> Just a thought. Can I use a cooking thermometer to check my flue temps. I guess I could drill a 1/8 " hole in the stack and just put it in. Does anyone do this.



Several recent posts on this topic. See THIS POST and THIS ONE. K-type thermocouples are very flexible in temp range and types of probes, and lots of quite inexpensive devices to read the temps. Have fun.


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## Tony H (Jan 16, 2010)

I got a couple that are about 1 1/4 inch and clip on with a spring loaded clip . There were in the plumbing / heating section aqt my local menards store for $15.00 or  $20.00 and seem to be pretty close in temp


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## muncybob (Jan 16, 2010)

ihookem said:
			
		

> Just a thought. Can I use a cooking thermometer to check my flue temps. I guess I could drill a 1/8 " hole in the stack and just put it in. Does anyone do this.



This is exactly what I did. Sealed it with high temp caulk and seems to work ok. Just be sure the scale goes high enough for your application. Mine goes to 600 and I know my stack never gets that hot.


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