Wood Gasification Boilers

Steve Ebels_3

As with any wood burner, you learn how to load and fire it. Starting from a bed of coals, and it doesn't take much, the owner tells me that he places some kindling and small wood (<3") on the bottom, opens the draft damper and goes in to have a cup of coffee. After about 15-20 minutes he'll fill the firebox and close the damper, which diverts all the combustion gas down through the gasification chamber. Within 5-10 minutes the boiler is in full gasification mode and continues as long as there is a call for heat and enough gas and smoke coming off the wood to burn.

The unit itself is HEAVY! I would not put one down a basement stairs. Walkout yes, stairs......no.
We installed this one out in the workshop and piped to the house. As of right now it's running without any storage and loses some efficiency due to cycling on/of/on. We have a 500 gallon tank coming from STSS that should be here in a couple weeks. Be interesting to see what that does to wood consumption that is already pretty low compared to a lot of other types of wood burners out there.

I'll post the water/flue temps here within a day or so.

Chris S

Wood Gasification Boilers

I am looking to install a heating system using a wood gasification boiler as the primary source of heat.
I had a Sime wood boiler installed at one point, but became a slave to it and so after 6 years took it out & sold it. As I understand it wood gasification is the most efficient way to burn wood. I am considering
HS Tarm, AHS Woodgun, and Greenwood, though greenwood scares me a little because they call theirs a furnace, I'm not quite sure why. I also found a Czech unit, but am not considering it ( fear of no support)

Does anybody know of any others available, and does anybody have good or bad experience with any units. I am not considering an outdoor boiler (totally different animal) Finally - what controls would I need for automatic change over to a conventional boiler- when the wood fire is exhausted- away from home etc.

Thanks
Chris

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John Abbott

gasification boilers

I cannot recommend the Tarm enough I have installed them in one form or another sincce the late 70s if I recall correctly.The new gasification boilers are incredible and I highly recomend heat storage.Tarm USA is the same Co. it was all those years ago it says a lot.
John

hot_rod

EconoBurn

is another one to look at. A gasification boiler built in PA. A solid company behind them.

I've been happy with my EKO from the Czech Republic, fairly advanced controls with outdoor reset and variable speed inducer.

Gasification units are a little more sensitive to wood quality and dryness. smaller fireboxes require more fueling, but much cleaner burns and lower wood consumption.

A buffer tank is almost a must as they have fairly low water content..

hot rod

JC_10

I have been firing the AHS Woodgun for over three years and am very satisfied with it. I have a rather large heating load and the TARM was not large enough. I believe the Greenwood is a copy of a boiler manufactured by a man named Fred Seton and I know of one installation in my area and he is very satisfied with it. I have also installed two other Woodguns, one with a buffer tank, and it does greatly increase the burn efficiency of the unit. As was stated, the quality of the wood, seasoned one year is best for the Woodgun, does change the burn greatly. My unit works best with wood around 18 to 20 percent moisture.

jim post

tarm

I installed a tarm in 2005 and have been very happy with it. There is a great deal of discussion on wood fired boilers at www.hearth.com....in the forum section. Go to "the boiler room".
http://www.hearth.com/econtent/index.php/forums/viewcategory/1/

Enjoy!

Mike2

Gasification Boiler

I have a BioMax from New Horizon Corp. which is similar to the EKO and is also European. I've been using it for about 6 weeks now and am very pleased. Your concern about support should definitely be a factor. I've found Zenon at New Horizon to be very helpful.

The BioMax control outputs a 12V DC signal when there is a fire burning. I send this to the coil on a relay to make or break the signal to the oil burner. I think there was some discussion on the hearth.com forum that the new EKO control does the same.

Steve Ebels_3

You owe it to yourself to check out Econoburn

We installed one a couple weeks ago for a customer and I'm amazed at the performance. I haven't taken any flue gas measurements but when you can nearly keep your hand on the flue connector at full burn........it has to be running in the high 80's efficiency wise. I'm going back to the job next week with the analyzer and see what the flue gas is actually running. It has to be less than 300 degrees F. The owner is burning oak that was just cut but has been standing dead for about 4 years. Nearly all the bark is gone and I'd guess moisture is 25% or less.

You can look them up at www.alternativefuelboilers.com and check it out. The little video they have on the site is exactly what the gasification chamber looks like during operation.

The installation must include a dump zone that opens when power is lost or shut off. This is the same with any boiler of that type due to fairly low (for a wood boiler) water content. The 100K unit we put in holds 28 gallons.

The boiler emits no smoke when in gasification mode and the owner reports total ash accumulation of about 1 qt in two weeks of burning.

Tom Hopkins

Steve, I would be interested in knowing your flue gas measurement. The econoburns are on my list for a future projects and I would like to know how they stand out.
Do you know how long do they smoke after each new load?
Luc

Tom Hopkins

Thanks Steve.

I am considering having several 300 000 Btu units piped on a p/S loop and a good heat storage tank because the load will be quite big. Has anyone piped several wood boilers in P/S before?

Ted_5

Garn

Check out Garn http://www.dectra.net/garn/ over 25 years.

Ted

design

EPA OWHH

Depending on where you live the new voluntary EPA OWHH rules may be a factor. Some communities are considering whether to make them a requirement.

Compliance results in an orange tag on the unit.
http://www.epa.gov/woodheaters/what_epa_doing.htm

I believe Vermont will have a particulate matter emission limit in March to go with their setback requirements for outdoor wood boilers.

Steve Ebels_3

Doing two Garns right now

We have a 1500 and a 2000 going in a new dairy barn as we speak. 8,000 sq ft of in slab radiant with about 4,500 of that basically under a roof but outdoors. They will be piped Pri/Sec into 1 DHW HX, 5 zones of varying temp and 1 high temp loop. Should be done in about a month and I will post some pics.

PS Luc: what type of load are you driving? All radiant slab, high temp, air handlers?

Tom Hopkins

One possible application would be radiant floors with some air handlers and baseboards. Other applications will probably be baseboards.

I would be interested of seeing the pics of the Garn and the econoburn setup if you have some.

Did you have a look at the outdoor gasification unit from Sequoyah Paradise at:
http://www.wdheat.com

Looks interesting.

Steve Ebels_3

Here's some pics

These are from a couple jobs we've since completed. Neither one of them have any piping worth mentioning from a technical standpoint. The Econoburn is piped P/S into the house........the 1.25" pex being the primary. Off from that we feed a manifold for panel rads and underfloor radiant. The second circ drives the HX in the furnace, and from there the main loop will hit a 500 gallon storage tank from STSS. The tank contains a 180' coil which will preheat the DHW and the 120' coil to dump heat into the water for storage. When the boiler goes out the HX process merely reverses and the heat goes back into the main loop from the tank. The amount of ash you see is the total accumulation of 15 days of burning. It basically burns everything there is to burn leaving almost nothing behind.

There are two Garn installs shown. The one in the big shop is 280' from the house, hence the 2" pex I think you can see in one of the pics. It heats 4,800 sq ft of in slab radiant in the farm's repair shop and a 4,000 sq ft house along with DHW and the in ground pool in the summer. The other one is in a "Garn Barn" addition on the back of an old garage which has been converted to wood shed. It heats the old farm house, the garage, the farm office, the repair shed and the chicken coop. All told, approx 6,200 sq ft.


002 is an Econoburn lower chamber in gasification mode. I don't have a shot of the chimney but all that was coming out was a wispy plume of steam, no smoke.

329 is a naked Garn as received from Dectra. It's just a BIG tank (this one is a 2000) with a firebox and an excellent heat exchanger in it. I really like the drawn through combustion air design. Little to no smoke when you open the door to load even with a fire in it. All other types will tell you to kill the combustion fan when loading. With the Garn you leave it on which keeps the smoke where it belongs.

317 is the front of a Garn. We use wood studs for the sides and top of the enclosure and steel studs with sheet matal cladding for the front. Regular fiberglass from 8" on the sides up to 20" on the corners. There is virtually no heat loss into the space.

333 is the intake and exhaust on a Garn.

336 is the fire that was burning when 333 was taken. Note the utter lack of creosote in the main firebox. Very efficient combustion plus the owner knows that seasoned wood is key. The gasification chamber is the small round hole you see at the back of the firebox.

344 is water temp and 345 is flue temp.

396 Just to give you an idea of the size of the Garn, Matthew is 6'8"............what he's smirking about is anyone's guess.

324 shows the side of the enclosure on this one before the OSB goes on. As you can see, you don't just set a Garn in place, pipe wire and walk away. They take some serious rigging to get in place and then you have to construct the enclosure around it.

Steve Ebels_3

Econoburn numbers

First off, a wood burner is a different beast because the fuel supply is always changing. You can set the air shutter for best performance and 15 minutes later the combustion numbers are all out of whack as your fuel changes state. So you pick an average setting and run with it. I wound up with a tad more air than the factory setting on the Econoburn 100 that I was playing with.

That being said, I'm pretty impressed with what I observed in the roughly 3 hours that I played with this boiler. I asked the owner if he would give me a ring when he had a fire in it that was about 2 hours into a burn so I had an average starting point. When I got there the boiler had a good bed of coals underneath 3 chunks of logs that were fully carbonized. I stirred the fuel a bit to settle the chunks and stuck the Testo in the flue to see what was going on. The burner was in full gasification mode with nearly the entire lower chamber filled with bluish yellow flame.

These are the numbers:

Flue gas temp 368*

CO 2630 PPM

CO2 11.2%

O2 5.1%

Efficiency 87.6%

Flue draft -0.04 wc"

Sounds like a good running oil burner except for the CO.

The next step was to load it with wood and see what happened to the numbers leaving the air gate setting as it was. I added approximately 25-30 pounds of wood and opened the flue gate to let the new wood get going. During this stage the excess air went way up and correspondingly the CO2 fell into the 5% range. I figured this was normal as the combustion air was blowing pretty much straight through the firebox. At this point the numbers looked like this.

CO 1618 PPM

CO2 5.4%

O2 11.5%

Efficiency 76.4% (that was as low as I saw it through the whole cycle)

After about 15 minutes I closed the flue gate to put it in gasification mode and monitored the analyzer. The unit started gasifying but the excess air remained high, like over 90%. It took me a minute to tumble to what was going on. The unit was in gasification mode, the wood seemed to be fully involved flame wise so why was the excess air so high?
Although the unit was gasifying, the wood had not reached the temperature where it is carbonized. As this began to happen the excess air dropped, the CO2 went back up and the efficiency climbed back over 80%. After another 45-50 minutes the numbers reached nearly the same point as the initial test. After another 15 minutes or so the unit reached what I would guess to be peak burn as flue gas was reaching 450*. The gasification chamber was filled with flame and the flue gas numbers actually looked as though it could use more air as the CO2 was over 13%. CO went ballistic, reading 4500PPM before I pulled the analyzer. I'd guess that during this brief period of 10-15 minute the efficiency was crowding 90%. Very soon after that the fire passed its peak and the numbers began to look more normal..... as if 80% from a wood burner is normal.

Conclusions:

You have to give a gasifying wood burner plenty of air in order to ensure that you can sustain gasification all the way through the burn cycle. If you set it to low you can lose a lot during the peak burn time period.

Econoburn has done their homework on boiler design. The boiler cranks out efficiency and burns clean. Although the wood being used by this homeowner is not quite what it should be (24-35% moisture on the logs I tested) the boiler handles it well with little sign of creosote buildup in the heat exchanger area. There is a pretty good coating inside the fire box. I'm sure it would be less with the moisture content recommended by Econoburn (<25%)

In this day of $3.00 fuel oil, soon to be crowding $4 unless I miss my guess, we in the heating profession are going to be seeing a lot more alternative type systems going in. It's our responsibility to acquaint ourselves with what's good and what's not. The Econoburn boiler is a good place to start. It's a pressurized sealed unit so it eliminates a lot of the inherent problems of open systems. As I understand it, they have the folks from ASME in the factory as of right now reviewing their manufacturing processes and will soon have the {H} rating making it acceptable for installation everywhere. They also have the same unit available soon in an outdoor model.

Home owners considering burning wood will do themselves a favor by using a unit like this as opposed to a typical outdoor wood burner with their sub 40% efficiency and horrible particulate emissions.

Tom Hopkins

Steve thanks for the numbers. It looks pretty good.

I would be interested about the condensation issue. I know that for the Wood Gun this is one of their key selling points.

Tom Hopkins

Nice pics.

Steve Ebels_3

Condensation issues

The Econoburn has a built in relay that protects the boiler from condensation if the water temp gets to low. It kills the system circ and activates a field installed bypass circ that sends the water directly back to the boiler. It activates when water temp hits around 128* and kicks back off at 136 +/- a couple degrees. Condensation hasn't been an issue on this unit so far.

Marc_12

Wood boiler plumbed to existing oil system

Just got an outdoor wood boiler installed 2 days ago. Supply comes into the basement, through a tubular heat exchanger for domestic hot water and then it feeds directly into the radiator system (no plate exchanger). I got 2 zones...1st and 2nd floors. Here's my problem. The wood boiler gets hot, say 180 deg, the supply and return pex hoses get hot but the radiators don't heat up. Everything is bled with the autofill. Autofill off after bleeding and everything wide open and depressurized. I turned the thermostat on the old oil furnace down so that it would be a back-up (set to burn at 140deg). Turns out that the 2 circulation pumps (taco) only seem to work when the oil burner kicks on. I would think that the zoned thermostats should call for heat and kick on the pumps while the oil burner does nothing. Any ideas on why my zoned thermosats aren't getting my taco pumps in gear?

I spent way too much money if the wood boiler will only give hot water to my oil burner if the oil burner calls for it.

Thanks in advance

Marc

Tom Hopkins

Hello Marc,
You might want to start a new thread explaining your problem. It will get more attention from the wallies. This is an old topic.

I am no expert but if your circulators are only working when the oil burner kicks in it is probably due to the controls.

Marc_12

Sorry about that.

Greg Stuckey

Wood gasification boilers

I'm wondering how long a full load will burn. Can you load the EKO three times in 24 hours and keep a steady temp?

hot_rod

It all depends on the load

My EKO 40 may burn all day if only one zone calls. Also the wood quality and dryness makes a difference.

It is fairly hard to match a wood fire exactly to the load. The best method is to run 'em hard and hot and have a buffer tank to take the excess BTUs.

It is also the most efficient burn mode when the gasification chamber glows red hot.

hr

Unknown

Hey Hot Rod,

Any feel for how storage tank size affects this? I know a fellow who's got 240 gallons of tank already.. sure would be nice to use it, if the improvement of going with a larger tank isn't large enough to warrant all that extra expense..

Kevin O. Pulver_2

The little bit I know

is that the heat storage tank is like a "battery"
The more you can store in your battery, the less often you have to charge it up. Bigger boilers require bigger storage tanks, but smaller boilers can take advantage of extra capacity also... up to a certain point I suppose.
Please let me know if I am missing anything or completely off the mark. Kevin

hot_rod

Rob

yeah., just check the loads against the tank size. If you have Siggy's HDS it has a buffer tank program to run various examples.

hr

gersfeld

Sequoyah furnace company

We purchased a whole house wood furnace almost 2 years ago. The first three years was supposed to cover 100 percent of any problems related to a manufacturers defects or workmanship. It is a limited warranty. The company was sold in the interim and now the new owner is refusing to honor any warranties. The warranty was part of the furnace purchase and not purchased separately.  We had a major breakdown in the furnace leaving us with no heat, except for an old oil furnace which is quickly running out of oil. The new owner says we must pay for the repairs and he will decide whether or not to consider reimbursing us for the claim on the furnace . I contacted a consumer law attorney online with the question and he said, "yes you can sue".  I wanted EVERYONE to know that the new owner of the for Sequoyah furnace company,Matt Cobra,  is refusing to honor any warranties for furnaces purchased BEFORE he took ownership. Lawsuits are being filed as we speak.  Do not sell these furnaces without informing customers. I am going to do my damnedest to make sure everyone in the freaken country knows that buying a furnace from this company is NOT a good idea! PLEASE PASS THIS ON!!!!!! To verify the truth about this email contact:Bethanie Gordon  At gersfeld@comcast.net

gersfeld

Sequoyah furnace company

We purchased a whole house wood furnace almost 2 years ago. The first three years was supposed to cover 100 percent of any problems related to a manufacturers defects or workmanship. It is a limited warranty. The company was sold in the interim and now the new owner is refusing to honor any warranties. The warranty was part of the furnace purchase and not purchased separately.  We had a major breakdown in the furnace leaving us with no heat, except for an old oil furnace which is quickly running out of oil. The new owner says we must pay for the repairs and he will decide whether or not to consider reimbursing us for the claim on the furnace . I contacted a consumer law attorney online with the question and he said, "yes you can sue".  I wanted EVERYONE to know that the new owner of the for Sequoyah furnace company,Matt Cobra,  is refusing to honor any warranties for furnaces purchased BEFORE he took ownership. Lawsuits are being filed as we speak.  Do not sell these furnaces without informing customers. I am going to do my damnedest to make sure everyone in the freaken country knows that buying a furnace from this company is NOT a good idea! PLEASE PASS THIS ON!!!!!! To verify the truth about this email contact:Bethanie Gordon  At [u][color=#0000ff]gersfeld@comcast.net[/color][/u]