Heat sinks on woodburners

[nothing to lose]

Why don't more people use heat sinks on wood stoves. wood burners?

 Just a little something I thought of when I burned my fingers some moving mine around last night

 Recently I got what I think are chainlink fence post caps, these are round and tappered to a point in the center. Kinda a round pyramid and they have a threaded hole in the bottom a little ways to be screwed down on something. What ever they are for I really don't care, I got a few dozen for about $3 and they are solid aluminum

Anyway for the last few days/week I have had a bunch of these just sitting on top of my round 55gal barrel wood burner. They get very hot! I can actually touch the barrel itself for longer than the aluminum. These pieces have a point on the top and a hole in the bottom so they stack well also. Last night I was stacking them and burning my fingers on them, mostly I was moving them with pliers except for touching them to see how hot they were.

Anyway I now have stacks of these things 3 high and air moves around them pretty good the way they are shaped. Really well when the fan is turned on. I think where the heat sinks are I am getting about 2 times the heat out of the burner (at least) compared to just air over hot steel.

We all know aluminum or copper heat sinks work better than air (or steel), we use them on all our computers in various places, and rectifiers. Is anyone out there using homemade heatsinks like this on the wood burner? No-one I know personally does, every woodburner I see is just plain steel or cast iron surrounded by air.

The aluminum is sucking alot of heat from the steel burner, that lets the steel collect more heat from the fire faster. Basically the faster we cool the woodburner the more heat the fire inside can put into the wood burner, same amount of wood and same burn rate, just collecting more heat BEFORE it escapes up the stack. Aluminum does a much better job of transfering that heat to the air then than steel does also, plus you've enlarged the area that the air can contact. I see no disadvantage at all unless you make an ugly one on a pretty wood burner, and that's just looks, I am going for heat!

Thinking about it realistically, thick heavy aluminum scrap is every where. You don't have to buy expesnive fence caps, bust up or nicely cut aluminum wheels into thick chunks, altenator cases, some valve covers, even various motors. I just got a junk bench grinder, it has 2 large ends made of aluminum about 1/2" thick I am geussing. Sort of shaped like bowls. Any of this stuff cleaned up a little and cut easily into good shapes would work well.

I just got another barrel stove kit yesterday, $70 kit for $20, new but has a few pieces missing (all the importnat stuff is there). When I build this one for at the rock house I will be doing alot to make it more effiecient. This barrel will have the paint removed down to bare steel then painted with high temp paint made for burners and stoves. Once I have it assembled I will be taking metal banding straps and making heat sinks for the entire barrel. Cut strapping to fit around barrel with a little extra length. Cut thick aluminum pieces and grove the bottom for the strap to fit into, screw the 2 together, wrap around the barrel tight and fold over the end of the straps to be doubled. Drill hole for small bolt, bolt ends together  and strap holds the heatsinks tight against the barrel all the way around. Very simple and easy and should double or triple the speed the barrel can heat the room.

Later when I have time to do some casting I will decide the shape I want for best results and just cast scrap aluminum into something nice and fancy that works well. But for now in a hurry, I'll just strap on scrap chunks to do the job.

My scrap dealer sells me aluminum for around 50-75 cents a pound depending what it is/was. Wheels are higher than other things often. Anything thick should work.

[TomW]

NTL;

I do some recreational aluminum casting, mostly ingots for future use. I just go to the local small engine guy and he gladly lets me haul off the dead cast parts. He says since its "dirty" Al nobody wants it.

After I collect a fair pile I take a half inch screen from a hammer mill build a big bonfire put the screen over it and toss on the cast scrap from the small engine guy. Is usually stuff like pistons cylinder heads blocks etc. The bonfire melts the Al which runs thru the screen onto the ground leaving most of the steel parts behind on the screen.

Stuff like wrist pins, valves, springs all get caught on the screen.

When the fire goes out there is a nice pile of Al on the ground under it pretty much ready to remelt and use.

Just how I have gotten a lot of high grade Al for next to nothing. I do like a bonfire too. A smart guy could rig a catch system that funnels the Al out of the fire into actual ingot molds I think perhaps, too.

Cheers.

TomW

[picmacmillan]

very interesting synopsis....temperature gained goes to temperature lost...or hot goes to cold....it would be interesting to do like you say and have it made pleasing to the eye, instead of all kinds of shapes and sizes....does it seem to heat the room better?, i would think there would be more heat available due to surface area being larger with the aluminum, and for a longer period,..i don't know, very intersting idea...i have seen folks use two barrels in a wood burning setup..one above the other and this is supposed to heat things up better also,....let me have another sip of my tea and think this one over hmmmm! :)pickster

[dudevato]

What comes to mind after reading your 'findings' is the fins on a motorcycle engine.  They are only there to get the heat out.  What about a small fan set next to the stove to blow a little breeze over everything?  

[nothing to lose]

Yes, I am certain it will heat the room far better. Using convection only, the only air you can actually heat is what contacts the burner basically. That air transfers heat to other air, rises and lets cooler air hit the burner to be heated etc..

Now with say 50 little 2" aluminum spikes poking out the sides into the air, you see all the surface area you gain for the air to contact. The entire 2" will be hotter than the surrounding air, so it is all transfering heat. Add to that Aluminum will kinda SUCK the heat out of the steel, the steel transfers the heat better (sort of).

My thought on that is the fire is only going to raise the temp of the steel so high, once it gets to that max temp and is holding steady, any more heat generated will be rolling up the stack to the great outdoors. Cooling that steel as fast as posable means it can absorb more heat faster. Same as blowing a fan on it. I heat the room by convection only alot and it works fine, but when I really want the heat I turn on a fan and of course I get far more heat from the same fire. I don't change the fire, I just blow cold room air against the hot steel barrel to heat more air faster.

Also another things I think will work quite well with this new burner. I will be adding a fake linner (tank) in the top to force the fire more to the sides. I was watching in a peep hole (bung) in the barrel seveal times now and I see the flames rolling very nicly along the top of the barrel inside and flowing directly to the rear and up the stack, even with the damper closed. The top of my burner of course is far hotter than the sides are. On this new one I will be placing a tank inside hanging from the top about 2-3". What this "SHOULD" do is force the flames of the fire out around the bottom of the tank and to the side of the barrel, thus heateing the sides far more than now. It will still let the heat and flames reach the top also as they flow around the sides of the false tank and upwards.

I realy don't like it when the flames are shooting up the stack, one more thing I plan to try out is to block the front of the stack opening (coffee can use here) thus forcing any flames to sweep around to the rear of the stack opening.

In watching the wood burner alot recently, and after reading a post about an over ahead daft for the fire. I am thinking using 2 drafts will also improve the burner alot.

First you need some air to the coal under the fire so it can burn. But as we know from downdraft gasifiers and other stuff, the oxygen is burned up in the coals and produces heat that bakes out more gas from the wood. Now this extra gas is in an oxygen free inviroment and cannot burn, so up it goes out the stack. How much this happens in the wood burner depends o alot of things. How much draft to the coals, how much coals, etc.. But it is happening and that unburned gas is wasted feul that could be makng more heat! I have recently been burning my fires with the bung open on the wood burner. I built it so it was to the side about even with the top of the door.

Once I get a good fire going and lost of hot coals, I close the lower damper about 1/2-3/4 closed and open the 2" bung. The coals have air to burn but a slow draft on the bottom, so most the draft is from the 2" hole. This draft is above the wood and coals and is drawn to where ever it's needed basically. I have been seeing much more rolling gas ball flames inside the burner this way than before. The oxygen in the air entering through the higher 2" hole is getting to the gas and letting the gas burn up, I bealve much of that in the past was unburned due to lack of oxygen and simply went up the stack wasted and polutting. The air hitting the hot coals basically fanned the fire, coals burned hotter, oxygen depleated, gas unburned wnet up stack.

 The problem I have with leaving the hole open is that it does let smoke into the house ocasionally of course if not a strong draft going and couple other minor things since it is high up on the barrel. So What I will be doing on this new burner is add a pipe to stop that, cap off the hole and run the pipe downward below the fire level outside the barrel, then the smoke can't flow out the upper hole since it would have to go downhill. Then I have the 3 dampers, one for the stack to outside, one for the bottom, one for the top. I should get a much better controlled burn.

I have some other things I plan to add to it after I get that much built.

[nothing to lose]

Hmm' a 20" box fan perhaps

 I got one pointed right at my woodburner and yes it does work well.

"the fins on a motorcycle engine.  They are only there to get the heat out. "

Exactly, the same thing we want to do with our woodburners. Remove the heat that is created inside.

Ideally it would be nice to just build an all aluminum woodburner, but that's not posable since we can actaully melt aluminum for casting with a wood fire basically. Blow air onto hot coals and melt aluminum. Wouldn't want that to happen in the bottom of a wood burner!

Most normall wood burners will never get that hot on the outside, but beware if you have one you often turn cherry red with hot fires, like those potbelly stoves. That might not be good for the heat sinks in that area!!

[whatsnext]

Nothing to Lose, How about just building a good stove? I know barrel stoves are cheap and all but a heavier, and well designed, stove will last for decades and give you no worries about wasting fuel or burning through. I heated a couple of my homes in Michigan with wood stoves and learned two things. 1.Keep the heat in the stove for as long as possible. This requires internal baffling. 2. Use outside air for combustion. A simple plate bisecting your barrel will do what you want but heating the outside of the barrel to a higher temp will result in it wearing through at an increased rate. Are you really heating your home or just the cold air that you are sucking in to it?

Be safe, John......

[ghurd]

Have you thought about using the fake liner as a heat exchanger or duct?

Seems like an in duct and out duct to the fake liner could get a little more heat out. Fan forced or gravity fed.

G-

[wooferhound]

Back in 1985 I would visit a friends house where he used a pot bellied stove to heat his shack. Occasionaly he would really fill it up with wood and it would burn so hot that the exhaust stack would glow brightly for a length of about 2 feet.

I always thought it would be a great idea to mount large fins of sheet metal around that glowing area of the stack to recover that heat into the room, instead of venting it to the outside.

[MelTx]

  Hello    Years ago I worked at a machine shop,next door was an aluminum smelter that made alum products.When we would leave one of the red grease rags on the work bench over-nite, in the morning it would be bright blue.Something from the alum smelter was doing this.I dont know what it was.I got another job as soon as I could.Having the hot alum in your cabin might not be good.

                                    Meltx

[K3CZ]

Whole bunch of good observations and basics of stove/furnace construction and firing, but all you guys are relearning and restating what was developed nearly 200 years ago by the guys who first put steam power to work!  For lots of ideas along those lines, antique book stores are loaded with books on "The Basics of Steam Boiler Design and Operation", etc, etc.  Carry on!!!!             K3CZ

[xboxman]

i got a small engine repair shop and i have some old heads from lawn mower engines with nice fins you could take a bunch of them and set on the wood burner then run a fan to blow across them ...

and i also have some things that are made out of steel with nice long fins and they wrap around my pipes. i save a lot of heat that would be going up the stack ..and they get real hot too .. i had ordered them out of a catalog about 10 or 15 years ago

game

[RickieBlue]

After reading some responses here, I remember visiting a friends house years ago, and the Dad, who was some sort of engineer, had designed a really cool woodstove to heat the house. The stove wasn't much bigger than a 5 gallon bucket but kept the house real toasty! He had installed a baffle about 1/3 of the way down from the top that sat on rails attached the the sides of the stove, but was about 4" in length shorter than the stove. There was a rod coming out of the front of the stove and he would slide the baffle to the loading end of the stove to start the fire then push the baffle all the way back after she was going pretty fair. He had 2, 1/2" steel tubes mounted above the baffle that ran from the loading end all the way back and then with a U turn, brough them back towards the front. These were plugged on the ends in the stove and he had drilled a series of 1/16" holes on the plugged ends back around 6 or 8 inches. He had a means to adjust the air flow on these tubes where they went into the stove, some sort of threaded caps, kinda like the old pot bellies...once he shut down most of the air under the loading door, he would open the tube air controls and because he had a glass window to watch, he would adjust the tube air to get the most awesome blue burn in the top of that stove would the wood gas. It was an engineering marvel. One of the key things is to temper the air you are injecting to get an efficient burn. Just my 2 cents worth! Thanks............Rick

[tecker]

 I've been using a two barrel stove Made from the heavy gage barrels .I got another

barrel to weld on to the side to the right of the burn chamber to make a wood gas / charcoal chamber .I'm hoping to get a brake in the weather to haul it outside and make the cuts and wield it in place . In the mean time I'm trying to think of how to rotate the cord wood over the heat ports and how big these ports should be. Input would be appreciated

[DBGenerator]

Careful with that Aluminum. It does give off poisionous gas when it melts and burns.

RickieBlue, You'll have to draw a picture.  I couldn't follow that.

Ever look at those fireplace inserts?  Metal tubes for a grate and a motor that blows the air through it.  Works great.

[whatsnext]

DB, There was a comertial version of the stove described. It had a second air inlet to help burn escaping wood gas. I think the availability of platinum catylists make them kind of obsolete because you could put one easily on the first baffle near the fire.

John....

[whatsnext]

It is odd how we try to reinvent the wheel. "Hey, how about a square one?". I love Ben Franklin's wood stove work. He designed many. The stove named after him is my least favorite which I always thought was a bit odd.

John.......

[ilyatin]

How about using a small sterling engine fan, not pointed at the room, but pointed at the fire. The heat from the fire will run the fan, blowing more oxygen to the fire, making it hotter. I imagine you can make the fire much hotter, than the heat you loose to power the sterling engine, and also would greatly diminish the unburned gasses due to lack of oxygen.

Just a thought.

Sven

[troy]

It's complicated.  Most efficient wood stoves use a firebrick lining.  Hmmm, firebrick works as an insulator.  Why would they insulate the fire chamber.  That's pretty much opposite to what you're doing.

And here's why:  You don't get good secondary combustion (and real efficiency) unless you can get the combustion chamber to 800F (I forget the exact number, but that's in the ballpark).  A stove without firebrick, especially with heat sinks on it, has a very low chance of getting those high efficiencies.  With low efficiency comes lots and lots of woodcutting and splitting and stacking and hauling and feeding and ashes removing.  Never mind the environmental downer of burning up twice as much fuel as necessary and adding to the particulate count in the air, and CO and CO2 pollution, etc.

And despite the fact that my stove is lined with firebrick, once it starts that secondary combustion thing, the heat rolls off just fine because the higher temperature more than compensates for the modest amount of insulation provided by the fire brick lining.

Now, on the stack, there you could use some heat exchangers.  But if you overdo it, you'll get a humongous increase in creosote deposits.  So check that stack regularly!

On the third hand, maybe your barrel stove never gets hot enough combustion to encourage secondary combustion, in which case you have nothing to lose by extracting more heat from the primary burn.

Your mileage may vary.

Good luck and have fun!

troy

[nothing to lose]

I have been using this one barrel for over 6 years now and it has not burned through yet, not even close. Durring the summer it is taken out of the house and sits in the yard in the rain. Since all we did to this one was burn off the existing paint before using it I am really surprised it did not rust out, but it has not! This year it shows to have alot of surface rust and a few very minor pits on the outside, inside is good as new.

Yes, I am heating a 16'X 70' trailer house with an extra 6'x20' tip out, this is the ONLY heat source other than cooking on a normal gas stove, and it keeps the house very nice (some times too hot)! We have in the past had the doors and windows open and fans blowing at 5F trying to cool the house when I over loaded the fire with smaller good dry oak and was trying to shut it down. That's no joke!  

Having used various comercail and my own home built wood burners in several houses and buildings at once over the last many years I have learned alot.

1, a round barrel does not "burnout" as fast as flat steel of the same thickness.

Geuss it has to do alot with the expansion of the metal, but those flat sheet metal type "things" do burnout fast with alot of really hot fires in them. My barrel has been though much worse hotter fires more often and is like new.

2, thinner is better for faster heating. When I come home to a cold house that has had no fire for a couple days, my barrel is warm and producing a little heat with just the kindling burning. The cast iron stoves are still ice cold and it takes a real fire to even warm them a little, by that time my barrel is producing a ton of heat.

 The heat I get into the room is the only thing that counts really and the barrel is the fastest to produce that heat with the smallest fire.

3, keeping the heat in the stove is pointless unless you are cooking in it

You want the heat into the room, the faster the heat travels through the barrel and into the room the better. By pulling the heat out of the inside faster there is less to go up the pipe, or the smaller fire you can use for the same heat.

4. , using heat sinks simply tranfers the heat faster, but does not increase the heat.
   
5. , I plan to add a fake duct to the top of the inside of the barrel, that will not make anything any hotter really, just a larger area will get just as hot as the smaller area. Currantly the fire and heat goes straight up to the top, all the barrel gets hot, but the top is by far the hottest of course. The fake duct will simple force the fire out to the sides more before it hits the top. If I haven't burned out the top, then I won't burn out the sides by increasing them to near the same temp as the top.
   
6. , it's not really a matter of keeping the heat in again, it's keeping it from existing in the wrong place, up the stack. If we extract the most heat we can from a smaller fire, we burn less wood at a slower speed for the same heat. That means we also have less heat going up the stack.
   
7. , outside air is a good thing when you can use it. Often it's not easy to just knock a hole into a wall in the right place though. I will be ducting the air into the burner also. air will enter the duct from outside the house, planning sometype of preheat using the exhaust stack but not decided totally what yet. There will be a spring loaded damper somehwere in the duct that when the air is warm/hot enough the spring will close the damper, as the air cools the damper will open. I have one of those heavy fancier woodburners that has this control on it (stove itself is burned out) so I just have to get it.
   
   

At home I can do whatever I want, but the rock house I rented I don't own so I am limited to things like ducting through the closest window or something. At home I may just cut a 6" hole in the wall for this, but I have to wait till later when I can take apart the wall, electrical wires in it and I don't know where it's safe to cut.

 Since I put other things there durring the summer and take out the wood burner I don't want holes cut in the floor.

A cast iron barrel kit doesn't cost much. I got the last one cheap due to missing parts, normal retail was like $70 or $80. That will out last our lifetimes if properly used. Like DON'T heat it red hot then toss ice water on it, it might not survive that, but normall use it will never burnout for sure. Add to that $10 for a barrel. Anything else you need like pipes you would need for any other stove anyway. So total cost is maybe $90. In 10 years maybe you need a new $10 barrel?? Pull the $80 kit, buy new screws for a couble bucks and you got your new burner.

 I've had freinds that bought expensive (junk) name brand heavy woodburners, they got less heat and burnt some of them out already. Cost them a hole lot more than $100 for alot less than 20 years!!!!

[nothing to lose]

Yes kinda gave some different thoughts to this.

Have not decided yet.

Burner #3 will be used out doors in a safe area for testing only basically.

With this one I am going to try installing one of my charcaol makers I think.

The trick is being able to load unload it and having an air tight seal.

What I am actually thinking is I could use the heat of the fire to both bake the wood and heat the house at the same time, also produce the wood gas. The wood gas could be used various ways. Simply piped into the wood burner and burnt to produce more heat. Piped to filters and a gennie outside. Filtered and piped to a gas burner in another room.

I would have to do much testing with that before I would ever install it in or near a house. Make sure it could never build any exploding presures or leak inside.

[nothing to lose]

Getting the fire hotter is not the answer.

The fire already burns hot enough.

Blowing more air into the coals will produce more heat, yes, that is how we turn steel red hot for blacksmithing and even melt aluminum to cast, using just wood charcaol.

NOT what we want in the wood burner!

Also blowing the air into the coals and making them burn faster hotter means they eat the oxygen faster, so you still have unburned flamable gas being produced with no oxygen to burn it, but since you have a much hotter coals now you would be producing the gas much faster also.

As for just blowing the air into the upper area away from the coals, that's not much good either. Actually so far it looks as though the fire will draw what air it needs simply by providing some type of inlet for it. Problem is normally that inlet is at the bottom where the coals eat the oxygen, so providing a second opening about 1/2 way up will alough the oxygen in the air to get directly to the upper flame area of the fire and then the gas will burn. Getting the full best burn would be adjusting the 2 dampers to work together. Air to the coals produces the heat to bake the gas out of the wood, and burning the gas produces lots of heat. When wood is fully baked it is charcoal, which of course is what is burning in the bottom area already and that also produces tons of heat.

[nothing to lose]

Yep. Those pot bellied stoves are great at turning things red

My dad used one with normal coal, it always glowed red around the mid half as I recall, but that was enough to keep the little 2 car shop hot.

You gotto watch out for anything glowing red, don't want melted metals dripping off, but ya heat fins would have grabbed alot of extra heat from that.

[nothing to lose]

I'm pretty sure it's nothing to worry about

 People use aluminum cookware every day, and I am sure if you look in the PC you are using you will find an Aluminum heatsink, unless you have a rare copper one.

 Under normal use I think cookware sitting on a gas stove exposed to open flame would be far worse than a heat sink sitting on a wood stove. Don't know if either are actually safe really, but my biggest concern would be eating that fried chicken from the aluminum skillet

 Or drinking the coffee that was boiled in the aluminum pan, or large 40cup urns.

[nothing to lose]

Hmm, sounds like maybe he was baking the gas out of the wood and burning that like the oven on a gas stove sort of.

If you bake the wood it produces gas which was the flames of course. If that's in a sealed container and you let the gas out, then you end up with charcoal if you don't let air in. Without oxygen the charcaol can't burn.

Sounds to me like maybe he was baking the wood to get to that point, then adjusting the airflow into the wood he could control the burn of the gas, but actually was not burning the wood right then, more like turning it to charcoal. The charcoal could then be burned anytime, or if he could seal off that chamber from getting any air when the gas was gone, then he could have cooled it and had charcaol for the grill latter.

Thank you much for that psoting about that stove, you may have givin me the answer to a problem I was trying to solve for something along this line.

[nothing to lose]

Ok, I'll give that some thought, not to sure about it.

The only things I ever really considered fire brick good for was to prevent burning out those cheapy (and expensive) comercail woodstoves with the flat steel sides. You know the ones I see in the scrap pile all the time because the bottom and sides are burned out. Fire brick will prevent or slow the burnout simply because of 2 things, it keeps heat off the sides in the hotter coal areas and also helps stop carbonizing effects of bruning out the steel.

Never really though of or heard much of the 800F and secondary burn zones for fire brick.

Now I have used fire bricks for things, other wood burners custom projects ect..

How does fire brick help get higher temps?? Or is that just supposed to be to protect the steel from the higher temps so it don't burn out?

I haven't seen much difference in real fire brick or my home made fire brick durring use. Injecting air into red coals melts many things, my clay and sand and straw does the same as other stuff once dried and the straw burns out of it.

If I thought there were any actual reason to use fire brick I could easily add it to a barrel stove.

[troy]

Here's a little more detail on secondary combustion that came from a ten minute google search:

"Let's start with a basic overview of how non-catalytic woodstoves clean up the smoke emissions. The concept is pretty simple: in order to meet EPA standards, you'll need to create a second fire chamber inside the woodstove's firebox to reburn the exhaust from the wood fire. The secondary burn chamber in an EPA approved stove is located at the top of the firebox, and is designed in such a way that the exhaust from the fire must pass through it on the way out the chimney. In operation, the wood exhaust ignites inside the chamber, creating a 1200+ degree flame (much hotter than the wood fire below) which burns up approximately 90% of the smoke particles as they pass through it. In order to fire off your secondary burn chamber, three things must be present at the same time and in the right amounts: fuel, heat and oxygen. The fuel part is easy: it is the smoke from the wood fire. Likewise the heat: ceramic blanket insulation is used above the chamber to trap the heat from the fire below and ensure lightoff temperatures. The oxygen part gets a little tricky: since the primary fire has consumed most of the oxygen available in the firebox, preheated air must be introduced into the reburn chamber so secondary combustion can occur. Your design challenge will be to figure out a way to preheat the secondary combustion air to the right temperature and cause it to be drawn into your secondary burn chamber in measured quantities that automatically adjust with the draft control that supplies air to the primary fire, keeping in mind that the secondary flame must keep burning and cleaning up the exhaust even when the primary draft control is at its lowest setting.

Tip: Scores of woodstove manufacturers have gone out of business in recent years as a result of being unable to engineer a stove that would burn clean enough to meet EPA emissions standards. The sad fact is, unless you are an exceptionally talented thermal design engineer with a background in wood combustion and lots of time and materials for prototype testing, your secondary burn chamber probably isn't going to work."

And here's the website if you want to read further:

http://www.chimneysweeponline.com/hohmade.htm

Oh yeah, and I was low on the temp.  Secondary burn occurs at around 1,200 F.  You just don't get that without some kind of insulation around the secondary burn chamber to allow the heat from the primary burn chamber to really cook that smoke.

Best,

troy

[ghurd]

Bad stuff comes out of Al at high temps. The coffee never got past 220'F, the baking pan less than 500'F.  I would look into that hard before it went inside my house.

G-

[juiced]

This a product i wondered about for some time.

  Then i saw one for sale @ canadian tire for about 30$ (i think). Im planning on having some milled out for me to try and market.

  These particular ones have a fan built it that work off thermal. Very sweet setup.

[tecker]

  Just to go on for a moment about the barrel adaptation to wood gas the top barrel pretty much captures heat and improves draft (when it gets hot ). the addition of a third barrel with seal door to load regular cuts and a grate with say 8 to 12 inch spacing

as the wood brakes down it  falls in to the fire box and more rolls into place

set the grate on a 45 top to bottom of the fire box port the gas can re injected or

or compressed . I've got a york all aluminum refrigeration compressor a stainless tank and a  5 hp Briggs add a gen set in tandem with the compressor which still has a magnetic clutch .  So wood gas to either burn for heat or compress for start up or run a gen set . Looking for a turbo charger for some added air and working on the pipe out of the top barrel and the gas chamber to a filter and I think the general filter material in the gas set ups is wood chips ( got a 25 gal barrel with a remova ble lid.

 sounds workable a sterling would be cool also as air handler but Short on skills there  

[Aelric]

I had 2 ideas, if you mounted aluminum or copper fins around your stovepipe and then enclosed that and ran water down it, couldn't you then have that go out to a radiator or even something like I saw earlier on this board.  It was a copper coil with a tube around it, you put a fan on one end and then the heat from the water could be transfered to the air, or if you want to get really into the heatsinks, braze on some copper or aluminum fins (heatsinks) to the copper pipe in the heat blower positioned so that the air easily flows thru the fins straight down letting the heat from the stovepipe heated water more easily be transfered to the air blowing thru.   Or a more simple approach just run air down the side of the pipe (enclosed with heatsinks) so that it can be directed into one stream.  Just a few idea's :-)

[Drives]

I own one of these stoves, and except for the fact that I don't like to shovel ashes, it is great.  Also, they claim to have the most efficent woodstove.  It looks like they have the secondary combustion chamber, and it is fed by preheated air from some pipes open at the bottom of the stove.  Mine works very well, and leaves very little ash due to excellent combustion.

http://www.cetsolar.com/ThermContrl.htm

 I don't know anything about the dealer, I just like the stove, and this site had the best info.  Good Luck.

[ghurd]

I believe CU gives off bad stuff when it is hot, too.

G-