Improved Gasification Tips

[Eric Johnson]

It got down into the 20s here in Central NYS last night, so I fired up the boiler in the evening. Even though I was using very dry wood, I got an unacceptable amount of smoke on startup and gasification failed to take off after 10 or 15 minutes. I poked around at the fire a couple of times and tossed in a few more chunks, but still got a thin stream of blue smoke.

Then I noticed a pretty substantial ash buildup under the nozzles (the EKO 60 has two), especially the back one. I cleaned out the ashes and immediately got full gasification and zero smoke out the stack.

Presumably, ash buildup under the nozzles compromises the gasification process. With a two-nozzle setup like I have, the back one always gets more ash buildup (I think because the air flows front-to-back), so unless you get down on your hands and knees for a look-see, you might not notice.

So that's one tip.

Here's a couple more:

When building a small fire (like I typically do), arrange the wood directly over the nozzles in a rectangular (teepee, pyramid--whatever you want to call it) fashion. This keeps the wood on the nozzle(s).

When building a fire from scratch, use some sort of natural accelerant to jump-start the combustion process in the nozzles. I use pine cones and/or yellow birch bark, but pitchy softwood kindling would probably work just as well. Get a lively fire going before closing the bypass damper, turning on the fan and initiating gasification.

I've noticed that when getting a fire going from scratch with the bypass damper and gasification chamber door open, the water temp at the top of the boiler can exceed the idle temp (80C with the RK 2001E), which means that when you try to initiate gasification, you're in idle mode and all you're going to get is smoke. I have a Taco 007 for recirc low temp return water protection. If I run the pump while getting the fire going, it keeps the boiler temp more even. Not sure what I would do without it. Anybody else have that problem and if so, what do you do about it?

Very dry wood is the absolute key to good gasification and smoke-free operation, but even with the right fuel, you can be frustrated if you fail to pay attention to details.

 

[SteveJ]

Eric,

Thanks for sharing your experience...

Now if someone could come up with a way for smoke free operation for a Seton/Greenwood, that would be a miracle ;-)

I try to build small fires by the air intakes after pushing the hot coals back - but smoking always.

Steve

 

[ISeeDeadBTUs]

Fired up the GW for a few days during this mini cold snap . . . what's this you say about the GW smoking? If you're up to temp and it smokes at these outside temps (currently in the 40's) you gotta' quite puttin Aspen in it :roll:

 

[Sizzler]

Thanks for the information Eric.

I recall you had mentioned blocking one of the nozzles with a piece of firebrick during warmer weather as to not consume as much wood. Could you please share you thoughts on the effectiveness of this technique?

 

[Nofossil]

I'll add another tip:

There seems to be a 'sweet spot' in terms of the volume of flammable gas that's generated in the primary chamber. Too much and you'll get puffing and banging and general misbehavior. To little and you won't get full output.

The solution is to avoid loads that are at the extremes: a load of all small dry stuff is not a good idea, and a load of all really large pieces isn't ideal either.

As Eric mentioned, you need really dry wood to start a fire. Once it's going, seasoned but not bone-dry is OK. I've had good results with wood at 30-35% moisture. Too high and you won't get a clean burn, though.

 

[jebatty]

Eric, I had similar experience with my Tarm as outside temperatures have warmed, but the apparent causes were different.

First cause: I "forgot" how to start the Tarm quickly and easily, resulting in a slow start and a long time to come into gasification. I am sure this also was impacted by second cause below. Remembered solution: in a criss-cross fashion, over the nozzle, I lay 4-5 very small splits per layer, three deep, air space between them. Then the paper fire-starting knots on top (top down fire start), light, close firebox door, turn draft fan on, leave gasification chamber door open, draft bypass open. Fire starts very quickly, add a few more smaller splits and rounds, let burn for a few minutes, close gasification chamber door, close bypass damper, and flames quickly roar through the nozzle, heats the chamber, and gasification in process quickly. Then load the firebox. My load is not jammed full, but a little loose. This seems to greatly limit the possibility of bridging.

Now with the burn going right, I still was having trouble keeping the flue temp where it seems to be best for me, 400-500, as it was staying in the 300-400 range and water output at only about 150-160 with 90 water in, not what I was experiencing during the winter.

Second cause: warmer outside temperatures resulted in reduced draft. Solution: reduce the manual restriction on the draft fan to increase forced draft. This worked wonders immediately, and all is now well. During cold winter I had to restrict the forced draft as it was being aided considerably by natural draft, which with warmer outside temperatures now is not as great.

With my pressure tank now up and running, I ran the boiler to drive the tank up to 170 top and 145 bottom, just to test the expansion tank capability and system pressure. PSI went to 19-20, expansion tank handled the load. This Fall when cold weather returns I will drive the tank to 180-160 just to make sure undue pressures do not build in the system.

 

[Eric Johnson]

Thanks for the information Eric.

I recall you had mentioned blocking one of the nozzles with a piece of firebrick during warmer weather as to not consume as much wood. Could you please share you thoughts on the effectiveness of this technique?

It works pretty well. Basically, what you're doing is cutting your heat output in half, which allows the boiler to run harder for longer. Ironically, that's more efficient. I haven't done it for awhile--since I learned a few tricks for running the thing with full power--but it's not a bad way to go in warmer weather and/or if you don't have storage.