Making my simple fire gasifier

@JO_Olsson, from Sweden, says in very cold weather, starting is maybe a little easier on woodgas. :rofl:


To be fair, I spent a good bit of time building the gasifier but mostly used scrap metal and I was having fun and getting lots of practice welding so it wasn’t wasted time.

Making the charcoal has been a learning process but using the better barrel to shovel the coals into after making it made a big difference in the amount I ended up with per batch. I should make another batch soon but I still have over half a 55 gallon drum waiting to be crushed so I haven’t bothered making more yet. Plus, with colder weather coming, I plan to use the house furnace to make the charcoal so I won’t be wasting the heat making it.

I’m not to the point where I could run a vehicle on it but it shouldn’t be any problem keeping enough charcoal to power my tools. I’ve run saws, grinders, a wood planer, the air compressor, and even the welder and log splitter using the simple fire gasifier. I run the wood chipper too but it didn’t seem to have enough power to run that but adding the water drip might help.

So, to answer the question about is this worth doing. I’d say, for me, I don’t regret it at all and I expect to use it a lot. I do still want to build another gasifier but this one does about anything I need it to.

I assume this is like a lot of hobbies though. Always some new modification to try and always the next one to think about building.

I still want to add the water drip and put this on a base but I’m close to needing to start working on the next one. My charcoal grinder works but powering it with a drill is a dirty job so that could be my next project.


No doubt about it. With gasoline, you don’t get a fine enough spray pattern to easily ignite when it’s really cold. Woodgas on the other hand is always in a gasious state. To find the correct air-mix right away can be tricky though - regardless of temperature.


I hadn’t thought about gasoline not atomizing as well in cold temperatures. I was thinking the oil would be thicker but didn’t know how woodgas would be any different than gasoline to fix that problem.

Getting the air mixture right was the only reason it wasn’t as easy as starting on gasoline and it took a few pulls. I didn’t time it but I’d guess it couldn’t have been much over a minute or two from the time I lit the gasifier until I had the generator running and producing electricity. Not as fast as starting on gasoline which usually only takes a pull or two and a little choke to get it to fire but definetely worth it. I filled up the gasoline tank to weld the access port on the side of my gasifier and have been running almost entirely on charcoal since I got that back together. The gas gage still shows full.

Looking at the generator’s manual, it uses 0.4 gallons of gasoline per hour at 50% load. The welder uses everything the generator can give and would like more but, assuming I run the generator over 4 hours in the last few days, that saved me at least a gallon and a half or over $6 not counting the fuel it would take to go to the gas station. In reality, that probably would have used over half the 4 gallon tank of gasoline.


For sure! My BCS per instance, l it WILL start on the first stroke on chargas. Set the air on the usual setting and pull the engine, one revolution and it runs. On petrol? Naah… hit and miss… might start on the first pull, if you are fast with the choke and know your machine well but usualy these engines require a few pulls…


Just wanted to put this here to keep from losing it. This shows one of Giorgio’s clean out doors and the gasket.


It took a little longer than usual today to get the generator running but it was still only 8 minutes. The generator was running but not fast enough so it probably just took some time to get the good gas through the filter and hoses. I didn’t try lighting a flare this time so it might not have been quite ready to run the engine.

This isn’t the final water drip but I didn’t have a 1/4" pipe tap to cut the threads in the old fire extinguisher container that I hope to use.

I didn’t have any actual projects ready so I didn’t run it very long but the water drip did seem to get the welder to run better than it was.


Thinking about the NEXT build.

This is probably another 20# propane tank but smaller diameter and taller than what I used for my filter. Quick guess it looks like about 10 inch diameter and the tank portion is around 18 inches high.

I’d like to try a downdraft charcoal gasifier possibly for use on a lawn mower so I’d like to keep it small.

I realize the run time wouldn’t be very long with something this small.

Looking at Matt’s no-weld ammo box gasifier it looks like there isn’t any ash clean out port which would make it almost as easy to build as the updraft simple fire.

Does anyone have any suggestions or see any problems with this idea? My thought is have the grate removable and just dump it all out to clean it. It will likely only hold a bucket of charcoal if that much.

I just got the valve off and haven’t filled it with water yet and don’t NEED another gasifier right away so if this is a bad idea feel free to say so.


brian, don´t worry, this is called the “gasifier fever”…not a serious desease…all here are infected though…reading here can just make infection…
i have now the seventh in work…
began 3 years ago also with some propane tank…
it is always surprising how long small engines can run with a little quantity of charcoal…


Brian if i can point out a couple of things to you that might help your gasifier running , the first one is on your filter you have what looks to be a pink piece of cloth tight across each hole , that means by doing that you have restricted the filtering area down to what ever diameter that pipe is times 2 , meaning it will start restricting your gas a lot faster than normal , replace that cloth with something like a sock or even place a disk of foam or felt over the top of your filter media .that will dramatically give you more surface area to clean the gas
You mentioned your next run took about 8 mins to start and took a while till it got good gas , the reason for that is a common one , fresh new charcoal will always start up straight away , but used once or twice charcoal will be harder to light and take longer to give off good strong gas , one way to help that is to try and crush the charcoal that lays in front of the nozzle and get some fresh fracturs in the charcoal , i used to take the lid off and poke down with a bar all around the nozzle to do that and it makes a huge difference to start up time and giving off good gas . Koen empty’s his gasifier out after ever run and refill with fresh new charcoal and does not have that issue , but for people like me that use a large container as a gasifier its not so easy to keep emptying out after every run .
All the best


Thanks Dave. After that last run I did poke a metal bar down through the charcoal and the level dropped a little so that should help. I shook the gasifier before the slow starting run but it had the filter attached so I couldn’t shake it real hard and I didn’t notice the charcoal level drop much.

The 8 minutes was the total time from lighting the torch to light the gasifier until I was producing electricity. Lighting the gasifier took only seconds and getting the generator started didn’t take any longer than normal but getting it to run right took considerably longer than usual. The generator run at a slow rpm and the air mixture valve had to be kept almost closed to keep it running but eventually (at around the 8 minute mark) the engine came to normal speed and the air mixer valve could be opened back up a lot which I assume means that the quality and quantity of gas being produced at first wasn’t enough.

Most of that problem probably was from not starting with fresh charcoal and not poking at the charcoal to break up and force down the charcoal closest to the nozzle.

I hadn’t considered that putting that felt directly over the holes of the filter’s outlet pipe would restrict the flow that much because that’s exactly how I had the bucket filter but that makes sense now that you say it. It shouldn’t have been the problem yet since this was only the second short run with that filter but it could explain why the new filter worked noticeably better than the old bucket filter. I had assumed it must have still had an air leak but could have just been those felt discs getting plugged up.


What Dave sayd.

I hadnt seen the sluggish startup problem with a downdraft thugh… maybee since it propagates fire from 5 nozzles instead of one.

For the sake of simplicity, absolutely no need for a cleanout door. I have a “hatch” (the 2" screw in lid from a oil barrel) but no dust ever acumulates here.
You will eventualy see the performance worsening a bit, this meant its time to refresh the gasifier. Ash builds up on the grate, clogs together in lumps. Dump out and thats it. On myne this happens over maybee 8 hours of full power run time.


Some time ago, in the company where I work, we changed the burner tubes in the natural gas boilers, it seemed to me that I could use this for a simple gasifier. I’ve been thinking about the construction of such a gasifier for some time, there will be a rotating disk for ash removal below, through which a central nozzle for air intake will be installed, I intend to use torofied wood as fuel.
Brian, I apologize for posting this in your thread.


Hi Tone, please post this gasifier also on your building threads so we do not lose track of this new build you are doing also. You are just producing one gasififer after another. Good job we like it.


I’m curious about the rotating disk for ash removal and your choice of fuel but it would be easier to find your builds if you started a new thread or added it to another one of your builds.

That being said, I don’t mind if you post here. I have a few more things I might do with my build but it’s pretty much done.

I keep thinking about putting this unit on a base but I kind of like the idea of reusing the parts on other builds. Specifically the filter. It fits this gasifier perfect but, at least for testing, it would be nice to just move it to the next build instead of building another one not even knowing if that gasifier was going to work.


I got curious how the flute nozzle was holding up so I emptied out the gasifier to check it.

Seems to be holding up better than the straight pipe nozzle did.

I’m still going to try building a down draft gasifier but I’m impressed with this one.

I did run it once with a water drip but mostly it was run without one.


Was the flutes pointed straight up?


Don, This was run with the flutes at a 45 degree angle. I did knock a couple small balls of slag off but they weren’t blocking any of the holes like the last time I took this apart where it was facing straight up.

I couldn’t quickly find the post of who (might have been you) suggested either 45 or 90 degrees but it helped.

Dumping this out gave me a chance to screen the charcoal before refilling it. There was a lot of fine dust and a few pieces of slag that I separated. Some of the fine dust was probably from poking at it to drop the level when I refill it and some might have been added in when quickly refilling it just to get running again. Some was probably ash.


I didn’t keep track of where I got this picture but it was Dave’s big simple fire. The big threaded fitting Gary Gilmore gave me works pretty good for filling my simple fire (I use a funnel made from a big plastic bottle) but this would be a lot cheaper. If I understand right, I think Dave just drilled and tapped the tank and uses silicone as the gasket. I can get around 2 hours running my generator hard before I need to refill mine or at least need to poke the charcoal down so being able to open it up with no tools is nice but there’s no reason the screws or bolts couldn’t be made with thumb nuts or some other DIY method to eliminate needing a screw driver or wrench.


Brian, we havn’t seen or heard much of Gary Gilmore lately. Is he retired now? He surely pioneered the dark side of woodgassing for us.


I’ve only seen him a couple times but he was making biochar I think plus he still uses the simple fire for the log splitter.

Also had many other projects going on just not posting here.

I’m pretty sure he retired from working so staying really busy now.