Successful burn with EKO40 primary set to less than 5mm

[Northwoodsman]

My EKO40 system has been running very well during the last 2 week extreme cold spell up here in Northern Michigan.

I have been re-splitting my firewood (into sticks) so that I do not experience the bridging that I experienced early on when I was using the larger wood.

Since I have been doing this I have experienced no bridging (finally !) . On the down side, I have experienced shorter burn times.

I have been running my boiler at 50% fan power, 40% fan opening, 5 mm on primary, 4 turns on secondary and 195-185-195 temperature setting.

I actually start out at 9mm on the primaries (I made the modification so that I can adjust this setting "on the fly") and after an hour or so, when things are burning well and the boiler is nice and hot, turn this down to 5mm.

Thus, to extend the burn times and extract more heat from the wood, I was thinking about elongating the slot on the primary slides so that I can reduce my gap to less than 5mm (the way it comes from the factory the slide bottoms out on the end of the slot and thus does not allow it to go any less than 5mm).

My thought is that I can keep decreasing this gap until I start to put the fire in the upper chamber out.

Has anyone tried this with their EKO (or other brand) of gasifier?

I was hoping to get some feed back before I remove the 12 screws on the front cover and make this adjustment (I'm also going to drill and tap these 12 holes and put in some nice socket head cap screws-the screws that came with the boiler are starting to strip out).

Thanks,

NWM

 

[Nofossil]

I'd be interested to get a better idea of what happens at the limits - what symptoms do you see that tell you that you've gone too far?

I'd really like to do a couple more instrumented burns, but my firewood is way too variable this year.

 

[Dave T]

I am burning 100 year old barn wood and my slots are long enough to close the primarys compleatly, with this stuff I am running about 1/8 open and still have fire in the loading chamber,yesterday I closed the primarys to about a 1/16 this was too far..I started getting puffing, and when I tried to open the loading door it puffed smoke before showing flames,another problem I had was without fire the loading door shelf got really runny soot on it and was literally dripping and running out the door on to the bottom door when I opened it, I was able to counter it by closing the secondarys some and opening the fan shutter all the way...Today I went back to what works well and thats minimal fire in the top chamber..Dave

 

[Duetech]

Northwoodsman,
My EKO40 slider plates will also go all the way closed but I had to modify them to do so. The left had slot length problems (1/8") and both the left and right had weld beads that prevented full closure so I trimmed the plates to accommodate the beads. When fully closed my boiler will still gasifiy though the flame is rather anemic. I have thought about putting a small length of fire brick in the center of the nozzle to force all the primary gasses into the areas where the secondaries exit the nozzle. I have already tried an experiment where I offset and lifted the U block to force the fire to roll and mix better. I will do that again if I block a portion of the nozzle. Mostly I'm waiting for warmer than 20*f weather so experimenting doesn't sound or feel so risky. I don't have the newer controller so I can't adjust the blower speed but my primaries are at 5.5mm and fan shutter opening is at 1/2" while the secondaries are only 2 turns out. I don't even adjust my blower up when starting a fire though I seldom have to start a fire because I have a coal bed to work with (no storage yet). The only mean adjustment I make, except for moister wood, is in the blower setting for colder weather. Then I open my blower to 5/8". 3/4" will work but then I start using more wood to let the boiler idle more.