Anyone using a Wood Gasification Boiler?

Where I live in Chenango County, NY there are a lot of wood users and woods. The popularity of the outdoor boiler has picked up recently and is causing the more densely populated municipalities to outlaw them, except for the wood gasification types, due to the smoke nuisance.

I am curious as to how they work and if they work as they say, i.e. nearly smokeless. I am also curious if the wood fire can be controlled better like a coal or pellet device yielding more efficiency. Lastly what's the cost.

Matthaus wrote:While you are waiting for a response you can check out the AHS site, they offer some pretty cool units.

http://www.alternateheatingsystems.com/boilers.htm

Been there done that. I am lookin for testimonials.

Thanks.

hs tarm has a nice looking unit too.

From what I understand you can burn almost anything in them with just about no smoke. I met a guy who was telling me about his and he said it extremely efficient as it gets an incredible amount of heat out of the wood but it gets it out a little too quickly. He also mentioned it took a long time from the time you started a fire until it was burning right. I didn't get a chance to stop by and check it out myself yet but I'll try to get him to join this forum so he can share his views.

I spent a good deal of time researching wood gasification. In fact none of these boilers are true wood gasification boilers because that would involve extracting the gases from the wood primarily to burn the gases, not burning the gases as an afterthought or a means to become more efficient.

There are several designs out there that are similar - they are called downdraft boilers. Tarm, AHS, New Horizon, and a couple others that are not quite as well known all use a downdraft design such that the fire is drawn down through the wood with the use of a fan which forces the smoke/gases through a secondary burn chamber made out of some type of concrete material that can sustain temps upwards to 2000 degrees.

The key to this type of system is heat containment. These boilers are most efficient when run at maximum temperature - burned HOT, until all fuel is consumed. The extra heat that the boiler creates that is not used by the house/shop/etc. needs to be stored is some medium - usually a water/glycol mixture - but I've read of some folks using some parafin (wax) mixture that seemed to hold the heat better. With the heat storage, a house could draw heat from the storage for 5 hours or so until you get home and prepare another 'charge' of fuel for the night.

One of the most important aspects to any boiler is the ability to replace parts that naturally deteriorate - like firebrick. This refractory material in the AHS unit can be replace by the owner at minimal expense. It was designed for that purpose. I imagine the same is true for the New Horizon and the Tarm units. The refractory in the Greenwood unit - which is not a downdraft boiler - but still an interesting design that has had mixed reviews, is entirely not replaceable. In fact, Greenwood has yet to get back to me on their plans for servicing the refractory material when it eventually deteriorates (it's all one piece!).

I actually had ordered an AHS model 180 and then decided to burn coal. I'm waiting the completion of a new construction - about 2500 sq ft complete with another 1000 sq ft finished basement to begin burning coal with AHS's coal gun.

I've done calculations on how much wood and what types of wood on different temperature days would give me enough heat coupled with the heat storage in a used 800 gallon insulated dairy tank. It was fun to work on that 'problem', but I think I'll just take the easy way out and burn coal!

I love to cut wood, but to expect my wife to deal with the boiler during the day was something I didn't want to put her through. I also didn't want to be dependent on wood as I approach retirement.

I hope this is helpful.

Pret

Since first posting the question I have had some time to research the various available gasification wood boilers and pricing.

Pret, you are right on the mark. The efficiency is there but it is cumbersome and expensive to capitalize on it. The PITA factor remains (though reduced by less wood cutting and hauling) because the handling and loading of wood for the boiler remains and is expanded by the complicated machinery maintenance.

As far as cash outlays go, wood is so inexpensive cut, split and delivered (in our area 150-165 per full cord) that the efficiency gains upgrading from a good wood stove are minimal to amortize the $10k price tag. The unit will wear out before it is amortized by cash savings. Also, the size of the storage tank is a drawback as is the boiler tending.

There are some units that burn woodchips and even wet woodchips which, if produced by woodcutters for fuel, could automate the fueling of the boiler, which would bring the unit up to a convenience level that competes with a stoker.

I have once again come to the conclusion though that woodburning really isn't cheap especially when you add all the hidden expense and work. Even when you can get your wood for "free", the cutting, hauling, splitting, stacking, storing, drying, hauling (again), stacking (again), and loading into the stove just isn't even close to cheap.

That's how I ended up burning coal.

Hi, I am new to this forum but have been doing a lot of research online on the wood gasification boilers. I am about to order a set of plans to build my own because the freight charges on these beasts are quite high.

Anyway I found a forum that has alot of dedicated gasification boiler users and that sounds like what you are looking for. It is hearth.com and go to the boiler room. You will find all kind of input and if you jump in there are many very helpful people that will answer any questions you have that have not already been answered in the many different threads.

Good luck! Rob

Thanks, Rob

I appreciate the referral but I have done the bulk of the research I need to do and I feel the investment isn't worth the fuel handling effort and the long pay back for the huge investment.

I have further reinforced my belief that wood burning is still a PITA under any burning scheme. Gasification addresses the problems of efficiency and smoke. However, with the cost of wood so cheap, cost efficiency wasn't the problem. Anthracite solves the problem of fuel handling (over wood) and the problem of smoke. If you factor the labor for wood (via any burning method) against the cost for coal, coal wins. Perhaps building your own will yield a savings but it must be a labor of love to pay you back fully.

Where I think wood gasification would really pay off is in very large installations for industry or commerce or wood fired electric generating plants. At that point the load matches the capacity and the economies of scale eliminate the personal effort PITA.

Good luck.

Get aquainted with this board. Lots of good info around there. Note the big thing is large water storage over 500 gallons.

http://www.hearth.com/econtent/index.ph ... wforum/21/

My father just bought a AHS 180 Gasification Boiler this year. I tried to get him to look at coal, but he figured he could cut his own wood and have a short ROI considering he was burning 1500 gallons of oil in his cabin alone. Not to mention the new 50x80 garage he would be heating this year for the first time I am not sure how much wood he is burning in it. I know that it has to be loaded FULL about every 10 hours or it will be out of wood. It is a really nice unit. Very Very little ash. The ash is as black as carbon and is a really fine powder. Has to be cleaned out once a week. When it fires up all you see from the stack outside is clouds of steam. Has a positive pressure exhaust so all flue pipe fittings must be air tight. If you have to burn wood this is the way to go, but I will stick with coal.

I have a good friend with a downdraft gassification boiler. He is very happy with it. But when I asked him if it is really smoke free he said not durning start up. He says that once it is in the gassification stage it is smoke free, but there is a transition from burning gassification, and during this time it still has the problems of creostote, and smoke...
These problems can be reduced considerably by starting the fire with very dry fast burningwood, then adding in the red oak and hickory and ash... but it still is not a good as burning anthracite...

I almost never see anything from my chimney, except during very cold weather I see a few wisps of ?? steam or white??? just as the boiler starts a burn cycle.. not a big deal at all. in fact it is less than a car makes idling in cold weather and only for about 20 seconds..

Greg L

This is late but I just really found this forum but the hearth network is the place to go. This is the address for the boiler room, the moderator Eric seems to be pretty well versed as well as an owner. One thing I have gleaned and I considered one seriously is the very high cost. Also you will notice that the way these guys operate efficiently is to have massive insulated water storage, usually around 500 to 900 seems what they like to use, burn em hot and let them go out. Nice but there is a lot to it and they say they demand very dry wood. That is one of the reasons I ended up coming by here to check out coal if I can get a stove to heat with both coal and wood depending.

Don't know much about it but found three videos.

Part one:
http://www.youtube.com/watch?v=2sCFpCpSTqE

Part two:
http://www.youtube.com/watch?v=JkyuMqDrpAo

Part three:

http://www.youtube.com/watch?v=arKLqwxbDqI

I give credit to a man named Greg
Brandon, Manitoba, Canada

I own and have burned a Tarm 2000 wood gas boiler for about 18 years. I am very pleased with the boiler except with one small but expensive detail. About every 5 years I burn up the refractory liner of the combustion chamber and have to replace it, cost about 750 dollars. Tarm has made some changes to the design to improve this problem but I have only burned the 3rd replacement for two years so I don't yet know how it will hold up. The furnace produces no cresote in the chimney only fly ash similar to coal. The only discharge during operation is water vapor (little smoke upon start up and shutdown). It likes good hardwood at low moisture, I avoid softwood and soft hardwood like Poplar

My employee also has a gasification boiler of a different manufacture and has had the same problem. This year he scrapped his old boiler for an outdoor wood boiler.

I burn about 10 full cord of hardwood per year heating a 1600 sq ft house with an attached greenhouse suplemented with a MkII Harman.


Steve