NSR Isabella Gasifier, DIY Filters, to 3HP Briggs and 10 SI Alternator

Hi Guys,

I bought a NSR Isabella Gasifier a few months ago. I made my own 3" Cyclone Filter. Then it goes over to a 5 Gal Bucket full of Bedding. The lid has a gasket.

When I first Ran the Isabella I could get a Flare pretty quick then I could pull start the engine. I recently had some fines plugging gasifier I couldn’t light the flare. Then I just recently seized up my my intake valve with Tar. I should have not run the engine cause I couldn’t get the Flare to stay steady. The Gasifier and Engine used to burn pretty tar free cause I would check spark plug and it was not black.

I get Water condensation in the Final Clear hose over to the Engine. Atleast that hose isn’t as black as the one going into filter.

I Think I need more pipe or a Gas Cooler to get rid of that water to Engine. I really can’t remove tar right. I need to get the Gasifier running better so it doesn’t Make tar. I think I have been trying to start engine too early sometimes or I am letting old Wood Pellets sit in hopper after running and they reabsorb water and fall apart.

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Welcome to the site, Dan!

You are correct that you can’t effectively remove tar. Once it’s been made and released from the gasifier, it will eventually migrate to the engine. Isabella is very small, and I imagine that makes it easy for things to get off-balance.

A cooler is always a good idea, it will remove moisture and provide a little extra room to settle out soot, as well as lowering the gas temperature, making it denser and providing a little more power. Everything between gasifier and engine will act as a cooler, so be prepared to collect water at all points.

The pellets can’t be left in the gasifier, as you’re finding out. They swell and disintegrate, then the fines will plug things up. Try to run it down to empty, or physically remove the leftover pellets.

@sabbadess you may want to chime in here.


The pellets are a problem if they are left in the gasifier after shut down. The tar factor— my thought— you need a manometer or vacuum gage. If your fan is pulling hard on the gasifier, it will probably reduce the tar to gases. This will give a good flare. Then you hook the engine up and it does not pull as hard and the tar is produced and makes it’s way to your valve stems. A vacuum gage or manometer will give you a comparison. TomC


Hi Dan,

I am sorry to hear about the engine. Here are a couple thoughts:

1.) If your starting fan is a “squirrel cage” type then it is too small and makes too little suction. That will keep Isabella from; fully coming up to temperature at startup, burning all the tars by letting the oxygen get to the restriction, or blowing the ash through to keep her running. Try going with an ejector so you get 4-6" of water suction.

2.) More cooling will definitely help with tar and water.

I have NEVER seen tar from the Mini Gas Station. That chipper has eaten a lot of wood gas and still starts on the first pull on gasoline.

Looking for tar on the plug is the wrong place to look. Properly mixed tar gas can burn VERY cleanly although it paves everything on the way to the combustion volume.

Let me know if there is any way I can help.

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Thanks for the Tips guys. I am keeping less fuel in Isabella Gasifier. . I can run the Engine and it will burn down all the fuel below the nozzles. Glowing pellets will be even with the top of Restriction. Maybe I am running this too low? on fuel and its making tar at the end.

The Gasifier and engine combo does run. I just got to make sure there are no fines plugging restriction so I get a good flare. Then I switch over to engine.

I have parts for a Ejector, but I am not sure if I have internal diameters correct. I could not find any Info on the Handbooks on ejector design. The NREL handbook shows a picture but no dimensions.

I will search the forums more for how to setup a Manometer. Thanks for the tips.

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This is a picture of the two types of manometer mounted on a board, with that silver tube at the top that we are measuring vacuum in. The vacuum is the black hose for my shop van.

I have two hose barbs in the vacuum line— one for each manometer. The first one has the plastic tube going into the top of a jar filled with water ( colored for better viewing). There are two holes in the lid-- one for the tube to go in and it extends to the bottom of the jar; the other is just a hole in the lid for atmospheric air. When pulling a vacuum, you measure how high above the water in the jar the water rises in the tube and that is it.
The second one is just a piece of plastic tube, one end plugged into a hose barb. The hose droops down and the other end is left open but at or above the hight of the hose barb. Suck some water into the tube; enough for it to stand about 10 or so inches up in the two legs of the tube. The water levels will be equal in each tube. When vacuum is applied one leg the water will rise and the other leg the water will go down. On this one you measure the distance between the high leg and the low leg. That is your vacuum in inches of water. TomC


Thanks for Photo on the Manometer. I set mine up after the Gasifier but before the Cyclone filter.
I tested the Fan and I was maybe getting a 1/2" to 3/4" with the Fan.

When I went to my Lowe’s Ejector(1/8" brass nipple inside 1" Black Tee) i could get 2" with about 5PSI on small regulator. I could get more Inches of water but it just made more smoke. I could never get Flare to light. The 5PSI seemed about the same Volume of smoke when I ran the Fan.

I got a small regulator and 1/4" ball valve to control speed.This was just a hour of trial and error on Sunday night.

I have been reading more about ejectors. I think I need a “Nozzle/Jet” at end of 1/8" nipple to convert pressure of air into Velocity, then that Velocity gets imparted to the Wood gas to create a vacuum to suck more wood gas? I also might need a converging tube, straight mixing section, then diverging section? Right now i just have a length of 1" pipe.

Oh yeah, I think I might have to retire the Soup Can as the Flame protector on the Flare. I need to test lighting flare right at point of exit of pipe. I used to light bottom of can(has holes) when I ran the Fan.

Lowe’s Ejector below(May need nozzle at end of Brass nipple?)

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Small Ball valve for Speed control(??) and Regulator for Pressure

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Manometer Location after the Gasifier. Should I move it down to Ejector? Or do you want to measure the Inches of Water right near the Gasifier?

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Dan; The monometer setup looks good. If you have a problem, I put about a 2 ft piece of 1/4 inch soft copper tubing between the pipe to the cyclone and the hose barb to dissipate heat that may melt your plastic tubing

Vacuum— do you have a shopvac?? That is what I would use or in my case I have an old Kirby vacuum. Hook the intake to your flare pipe and the exhaust to another piece of pipe ( possibly with a can ) for the flare. Get a dimmer switch for overhead lighting and hook that in like with the vacuum so that you can control the speed of the vacuum and thus the amount of vacuum.

I have a large gasifier and I pull about 10 inches of water for start up. The squirrel cage type never worked ( I have a bunch of them that I modified to no avail.) I know nothing about the small size you are using but would guess you would have to pull about 4 - 6 inches.

You said you got more smoke with the ejector pulling 2 inches. Try for more inches but go ahead and let it smoke. The first smoke is probably a lot of water coming out. Let it keep running. The pellets all have to be reduced to charcoal by the time they get to the nozzles. When it is smoking I think you are still “burning” wood blow the nozzles. Once you get everything passing the nozzles into char coal, you should get gas and a flare. When this happens you may not even see any smoke coming off your flare. TomC

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Hi Dan ,
You mentioned not being able to find dimensions on your ejector , I think Stephen has all those details posted somewhere , your best bet would to speak with him .
On the photo’s you posted , the first one is a picture of a T with the long brass pipe/ nozzle next to it , I am sure that brass pipe should only just go past the centre T to create the vacuum , I have used many Kongskiled injectors over the years and that’s how there systems work , having the brass pipe too far up will reduce the amount of suction I think .
All the best