Attn EKO-60 Owners -- Stack Temperatures -- What should they be and what do they indicate?

[cguida]

Can someone explain gasification boiler Stack Temeratues -- what they are typically, and what they indicate?

I am a new (and inexperienced) EKO 60 owner, and I don't really know what to expect. I had a fire going yesterday to charge up my tank, and try as I might, I could not get the stack temperature over 200F. I built what I thought was a hot fire of (dry) junk softwood, and let it go in by-pass mode. I thought this might get the stovepipe up to 300 or better still, 350. But no luck -- stack temperature didn't even get to 200, and meanwhile the water temperature in the boiler got up to around 150 so I closed the by-pass and burned the wood gas. Stack temperature settled down around 175, and stayed that way throughout the burn.

Everything seemed normal (far as I know), except the stack temperatures seem abnormally low. Does a 175 stack temperature mean something that I should worry about? Or is it just really effective heat exchange? Isn't there some minimum required stack temperature to remove products of combustion before they condense inside your chimney? Speaking of chimneys, mine has a very strong draw.

So in general, what should stack temperatures be, and what does it mean if your values are significantly different?

Thanks
Smee

 

[Hydronics]

Smee,
Congrats on your new 60. How do you like it? Do you get good clean gasification? I just did the third firing of my EKO 60 last night. I haven't seen stack temps over 150 either, even when I have a smoke free clean burn. I have a surface, not probe stack thermometer though so my numbers will read lower. I know a new boiler needs to have the the remaining water in the refractory cooked off & this may not be complete for us yet.
I'm not convinced that the secondary tubes are lined up because adjustment of the secondary screws has no effect on the torch even with the fan shutters mostly closed. I've read of a few guys with 60's who had tubes which were not aligned with the nozzle holes. I plan to shut down at some point & try to verify alignment.

 

[stee6043]

My EKO 40 stack temps, measured by a surface thermo on single wall pipe 12" from the EKO outlet, run between 300-450 during really good gasification. I typically will not close my bypass and turn on the fan until I have at least 300 on the thermo.

This is just my experience, however. I'm sure others will chime in...

 

[timberr]

He Smee,

Welcom to the Gasification club! I have a EKO 25 and the surface mount Thermometer on my 8" pipe typically is right around 200', the temp inside the flue is higher. I burned for 8 weeks last winter, I cleaned my chimeny this year and it was clean.

Good luck, don't worry in a while this will be second hand and you will load, light and let it run all on its own.

 

[flyingcow]

Not an EKO, but my stack temp is usually 400. 175 seems low, seems like you would have condensation problems? Just guessing. Talk to Polish guy at New Horizons. Can't remember his name.

 

[Nofossil]

There's a big difference between surface temp measured by a magnetic gauge and internal flue temp measured by a probe. I'm usually under 200 degrees by the surface thermometer, but 400 degrees by the probe.

 

[gradwell]

Smee,

I am a newbie to this as well. I fired my Econoburn 150 for the first time about 2 weeks ago. I burned for 3 days the first time with internal stack temps hovering between 250 - 300 and water temps of 160 - 178. After the 3 days I let it burn out just to check things out. I then fired again for another 3 days, internal stack temps remaining the same as before. When I let it burn out this time, I checked the entire stack for signs of creosote. Saw nothing but a very fine coating of fly ash on the entire interior of the stack

Moral of my story is that I dont know at what point temperatures create creosote issue but at 275 average, I have no signs at this point. I beleive that this fine coating of ash is actually what we are shooting for. If you are using an external mount thermometer< I believe 150 - 175 would equate to my 275 - 300 Internal temp.

 

[Gooserider]

There is a sticky on the first page called "Fine Tuning EKO" that may answer most of your questions - probably be worth a read if you haven't looked at it yet...

Gooserider

 

[jebatty]

My rule of thumb is that surface flue temp, about 18" from the exit from the boiler, will be about 1/2 of the interior flue temp. This rule developed from placing a magnetic flue surface thermometer adjacent to my probe thermometer on the flue. Can't vouch for the absolute accuracy of the thermometers, but they give a good relative read which with experience is good guide to how well the boiler is operating. Note: flue temps rising over time is a good indication that hx tubes need cleaning. I brush mine every 2-4 weeks, depending on how often and long the Tarm is fired. Every brushing results in a very noticeable drop in flue temp.

 

[cguida]

Thanks all for your responses.

I guess I will take NoFossil's comments and data to heart -- chalk it up to measurement error, and just not worry about it.

These temperature readings were with factory settings -- fan apatue wide open; fan power full. Lately I've been fiddling with cutting the air back, and this seems to have resulted in both a better burn and a somewhat higher stack temperature.