Thanks Tim I see it now!!!! I have taken a different path then most and purchaced all new components, 12" auger tube for combustion chamber with 16" auger tube for heat exchanger housing, and all related tubing 224.00 total, I just need to get the burners or burner built, the heater is a duplicate of GEE DUBBS, and i will draw air from the ceiling of my garage at the overhead door and expell the air after it goes thru heat exchanger area of stove just above floorlevel and faced toward opposite end of garage, I am using a inside duct, draft inducting fan on a thermostatic 150 degree snap switch in heat exchanger to control air flow. I think it will do a fine job, it's -15 degrees here tonight so i really need to get in gear...Tigman

Legal -- One nice thing about the seperate bowls is that you can build several styles of upper bowls for testing. I think one of the big advantages of feeding fuel to both bowls and having the draft for both bowls is that you continuously add heat to the top bowl, this added heat dramatically improves vaporization which makes for a much cleaner burn and less smoke.

I have been running the 2-bowl burner for a couple hours now on 100% used engine oil, much to my surprise there is no engine oil smell as there was with the single bowl and ,even I find this hard to believe, but there is absolutely NO visable smoke coming from my chimney even though I am feeding about 3 pints/hr of oil. It is dark outside but the moon is up, getting the chimney between me and the moon shows no trace of smoke. I hope this is true, it will be in the 30's here by thursday so will have a reason to burn in daylight and know for sure. Looking at the burn in the fire box I think what is happening is this -- The lower bowl burns cooler than the upperbowl, I can see a bit of smoke coming out from between the bowls but this smoke has to pass through the hot flame from the upper bowl to get to the stove outlet for the chimney, the smoke must be being burnt in the hotter upper bright yellow flame. There is no visable smoke coming from the burn in the upper bowl as the fuel is being vaporized more completely due to the extra temp of the bowl, this fuel vapor has to be HOT and is mixing directly with a large amount of cool air ramming down the cold air intake, makes for pretty complete combustion.

The 2 1/4 inch OD cool air intake pipe I am using is considerably smaller than the Sanders 4 inch pipe, this likely increases the speed of the incoming air as my stove rumbles audibly when burning, Sanders used a reducing bushing on the top of the cold air tube to control the burn, I leave this tube open and adjust the flue damper to do the same control.

When burning wood I control the draft using this same flue damper, with wood I usually run it almost closed but with this burner I can not close it more than about 1/3 closed or the burner starts to produce more smoke. This is allowing a good bit of heat to go up the flue but it looks like one of the conditions of this burner. All is not lost in my case as I have a brick chimney in the center of the house, the heat is collected by the bricks and slowly radiated back into the house, makes for nice even radiant type heat.

Fuel feed -- Dripping down the air tube has proven to keep from having the bottom of the fuel feed tube damaged by excess heat from the fire. I am using the sander's approach of restricting the tube just at the end, I run a 1/4 inch OD steel brakeline tube down the cool air tube but I brazed a 1 inch long piece of 3/16 steel brakelin into the end of this 1/4 inch steel feed tube, this seems to make nice drips or stream, depending on amount of fuel being fed, anything above about 1 quart/hr is actually a stream. The end of my fuel drip tube is 3 inches up inside from the bottom of the cool air tube and the cool air tube is 5 inches above the top of the upper bowl, 4 inches showed some errosion from heat.

Sanders indicated he has about a 30 ft head of pressure from his fuel supply tank, and this is enough pressure for a stable fuel feed, a local fellow here has his fuel barrel on the second floor of his shop and the burner on the first floor, even this amount of pressure works OK for him. I don't have any conveniant way to get my fuel supply tank that high in the air so I am using a positive displacement gear pump from a oil fired furnace as my fuel control. This gear-type pump moves a defined amount of oil per each revolution, I am turning it slowly with a salvaged 12 volt DC automotive windshield wiper motor, this motor is being powered by an adjustable power supply for now (eventually an adjustable power supply powered by a 12 volt auto battery), more volts to the motor turns the pump faster makes more fire. This is proving to be very repeatable and makes for a nice control to set the amount of heat from the burner, no return line needed. just connect the drip feed tube to the output of the pump. 2 volts turns the pump at about 15 RPM, this moves about a pint/hr, 4 volts = 30 RPM = a quart/hr, 8 volts = 60 rpm = 1/2 gallon/hr, this is as hot as I have run it so far.

The used engine oil is burning a bit different than the veg, it sizzles and sparkles a bit as it vaporizes. It is also producing a bit more crud/ash than the veg but this stuff is quite different. It is not a hard coallike deposit but is lite and flakey and every few minutes a big chunk will release from the bowl, rise up, and burn up in the upper bowl flame as it was headed for the chimney, odd ? Will know more tomorrow after everything cools down but looks great just now.

This seems to be just what I need to heat my 20x26 shop. I have a small wood burning stove and a supply of waste motor oil and wast veg oil. I have been looking for something simple, cheap, and easy to build. Your burner and Sanders burner fit the bill. How large a pool of oil are you burning?

lmark -- I have not turned the burner up much yet, I have been burning from a bit less than a quart/hr to a bit more than a quart/hr, turned it up to a 1/2 G/H and had way too much heat. It is a bit hard to say exactly the fuel pool size as the upper bowl does not actualy have a liquid pool of fuel, it runs hot enough that it vaporizes all the fuel that runs into it. The lower bowl has about a 3 inch diameter pool of fuel but the amount of fuel in the bottom bowl is based more on the size of the drip hole in the upper bowls leaky fuel shoot than on the amount of oil being fed to the burner assembly.

I burnt motor oil for about 6 hours last night, it DOES make some hard coal deposits in the upper burner but the lower burner deposits are much softer and do not stick tightly in the bowl.

One of the main claims in the Sanders article is that by keeping a pool of liquid oil in the bowl burner the crud deposits would be much easier to remove. This is proving to be true but at the cost of not vaporizing fuel as well as a hotter upper dry burner bowl, this leads to a bit more smoke being produced from a 1-bowl burner. A 1-bowl burner does not get hot enough to vaporize the fuel as fast as it is dripped into the bowl so the only vaporization is from the surface of the pool of liquid fuel. keeping liquid in the burner bowl does seem to cause the crud to be much softer and sort of foamy, it also does not seem to stick to the bowl.
I cleaned the bowls today, the lower bowl had about a 3 inch diameter by maybe a 1/4 inch thick "pancake" of foamy, crusty crud in the center of it. I expected this to need to be scraped loose but when I barely touched it with the scraper the entire pancake dropped out of the bowl, all I had to do was wipe out the remaining oily residue with a paper towel.

The upper bowl runs MUCH hotter than the lower bowl, this causes the fuel to be vaporized as fast as it drips in so there is no liquid pool to work as a barrier between the fire and the metal bowl. This higher heat boils out everything that can vaporize from the fuel and leaves only the solid "coal" type residue. Since there is no liquid to act as a barrier between the fire and the metal bowl the coal sticks to the metal a lot more solidly.
I had a couple of tablespoons of coal in the upper bowl from last nights 6 hours of burning engine oil, I had to do a bit of scraping to get this out of the bowl. The largest amount of coal is at the point that the cold fuel first drips into the burner, as the fuel runs around the air passage tube in the upper bowl it is heating up and evaporating, the farther the fuel has moved in the bowl the less coal it produces. The coal crud has a shape sort of like a wedge shaped orange slice, it is the thickest at the point where the fuel drips off the fuel shoot and first hits the bowl, then thins down as the fuel runs around the base of the air passage pipe. I don't know if this is because as the fuel gets hotter it vaporizes faster and does not leave as much coal -or- if it is because the bulk of the crud that makes the coal turns solid as soon as the fuel hits the hot metal so there is less crud stuff left in the fuel to turn to coal the longer the fuel is in the liquid state as it flows around the base of the air passage pipe (I suspect the latter is what is actually happening).

So - The 2 burner bowls are actually working on two different principals, the lower bowl burns cooler and holds a liquid pool of fuel, this causes a bit more smoke to be produced but it also allows the bowl to be cleaned very easily. The upper bowl is burning much hotter, this creates a more complete burn so there is not as much smoke but at the expence of producing the much harder coal crud that sticks to the metel.

I think the redeaming factor of the 2- bowl burner is that the lower bowl's extra smoke has to pass throught the upper bowls much hotter flame so most of the smoke is burnt there before it can get out of the heater.

Motor oil as fuel -- This burns just fine and the burner started from a cold start by starting the drip, waiting a few seconds, pouring 2 ounces of diesel into each bowl, lighting the bottom bowl with a propane torch - holding the torch a few seconds til there was a good burn going, then closing the stove. The bottom bowl burns vigorously and the upper bowl self-ignites in about 30 seconds -- Stove is lit. This same procedure works with cold veg just as well.

There is a bit more soot produced with motor oil than with veg, veg shows almost no soot in the burner chamber where motor oil will have a very thin soot coating all over the chamber if the burner is set to a very low amount of heat, if the oil drip is turned up a good bit of the black soot layer will burn out of the chamber. With veg there is almost no soot ever.

One other thing I noticed with motor oil, the bottom of the upper bowl was covered with a very thin 1/32 inch thick layer of loose soot, this wiped cleanly away with a paper towel, there is no soot here when burning veg. I think the veg simply is burning at a higher temp so both produces less soot and also burns away any soot that does get created.

Early conclusions about cleaning -- It looks like the bowls will need cleaning daily weather burning motor oil or veg. If you burn your heater 24/7 I would suggest making up two sets of bowls. The burner will go out within a couple minutes of turning off the fuel drip, simply remove the crusted up bowls and put the clean bowls in. The burn chamber will still be hot so the burner will relight easily (still will likely need a bit of diesel for startup fuel) and you can clean the crusty bowls later.

I realy realy like the fact that I can turn the amount of heat up/down by simply turning a knob that changes the voltage to the fuel pumps windshield wiper drive motor, way easier than carrying in more armloads of wood..

Tim;
Congratulations on your experimentations and also for being generous enough to share your experience and recommendations.
This one is definetly on the short "to-build" list. The twin burner concept is a good idea too; easy to make and then just swap 'em out.
I am getting a Pot Stove soon and will be using it to heat the reactor house but this type of unit is considerably more efficient, and uses staright veg, another benefit.
I am following this thread with great curiosity and appreciation.

Tim

It sounds like you have some sort of "after burner" effect going on...

Have you tried adding forced combustion air to it ??

Forced combustion air -- I pretty much have that now with the natural draft, this is caused because the combustion air inlet tube is mounted through the top of the stove and is directly above the center of the burner (I keep the normal wood stove combustion air damper closed when using this burner). This is one of the most innovative developments that the folks at Mother Earth News came up with in there original development of the MEN drip burner.

My combustion air inlet tube is only 2 1/8 inches I.D., this causes the air being drawn through by the normal chimney draft to be moving fast, the burner roars now, don't think it needs any more air, it could use some better means of mixing the air/fuel vapor as this is another element of more complete combustion, I just havent figured out what to try to make improvements in this area yet.
I am considering making an inverted bowl cover for the top bowl that has many small holes around the rim where an upper inverted bowl will meet the existing bowl rim, the idea here is that this chamber will become a fuel vaporizing/fuel-air mixing chamber rather than actually burning the fuel vapor directly in open air as is done now. I hope the incoming air being rammed into this chamber from the top will mix with the fuel vapor and this well-mixed fuel vapor/air will be forced out of the small holes around the rim and burn like a normal gas stove burner, maybe even with blue flame rather than yellow. If I look down the air inlet tube now I see a bit of blue flame from the 1/4 inch holes in the upper bowl's air passage tube so it may work to some extent.

This would basically be similar to a normal camp stoves vaporizing tube but it would be easily cleanable by simply lifting the top inverted bowl off of the lower upright bowl (of the upper bowl unit) and scraping out the coal residue.

Weather forecast says highs in the 30's and lows in the teens for the next couple weeks or more, The burner will get a good testing for a while, works well enough for now. In fact it works well enough I am considering making up one of the Samual's style heaters using a gas water heater tank as the stove housing for my garage. It would be nice to have a warm place be work this winter while finishing up the work on the syphon-style gun-type oil burner and another similar syphon style gun burner using a remotely located flame head from a torpedo heater, this would be similar to the Mobius concept except it eliminates the need for the tough-to-maintain oil pool. The fuel is routed to/from the burner nozzle adapter through 1/4 inch tubing and circulated through the adapter rather than being pooled in the base of the burner. This is intended to become a vertical flame oil burning insert for another wood stove that has a larger vertical burn chamber about the size of a 30 gallon barrel.
I also could process veg all winter inside rather than stacking the yard full of solid cubees and waiting for warm weather to process them. Squirls or rabbits have a habit of chewing holes in the bottom corners to get at what must be food to them, problem is that once the oil thaws in the spring it ends up draining out all over the yard.

I cleaned the bowls again today after about 8 hours of burning motor oil, pretty much the same condition as before, a couple tablespoonsfull of crusty coal on the top bowl and a softer foamy pancake in the bottom bowl. Only differance was that when I turned the bottom bowl over and bumped it the pancake broke apart into 4-5 pieces, most fell loose but I had to pry out a couple pieces. took all of about 5 minutes to clean both bowls using only a dull pocket knife.

Tim,

Comments and Ideas,

First the comments:
I stongly believe you need more combustion air. I do not think it is possible to burn oil completely without it.. Natural draft is not enough in my opinion.. (and i'm certainly no expert but experience counts right?)
By getting a more complete burn, you extract more energy out of the oil and thus you can use less fuel to achieve the same heat output.

Suggestions:
For your air intake tube, Get the air spinning.. Take a look at the end of a gun style burner.. They have this little air diffuser at the end.. From reading another thread in this forum, I think I just learned they call this a retention device.. I call it an air diffuser.. It looks like a jet engine fan blade but doesnt move.. Put one of those at the bottom of your tube and blow air in.. They are easy to make with a pair of tin-snips.. Or, another idea.. Have you ever installed a radiant heating system? You know, the kind that hang from the ceiling and have a reflector above them? These are long tubes.. The manufactures supply a screw looking device that slides down the center of the tube that gets the air spinning inside.. This creates a heat-scrubbing action to transfer more heat into the tube.. Maybe this same device would help get your air spinning? You could make one easy.. Just take a flat stip of metal that is the same width as the I.D of your pipe and give it a few twists.. Think it would work?

I have to say this again... I do not think it is possible to cleanly burn waste oils without forced combustion air.. You don't need much.. A hair dryer would probably be to much..

Guys, I remember from when I was a youg fella, that some "space-heater" type wood fired heaters, had a (vital component) lattice of copper strips located above the firebox. The principle was that the copper (4mm gaps) would heat up enough to burn any residual value out of the smoke before it entered the chimmney. In my area the most common firewood was sappy pine, so these heaters were the best way to go. I tried a search for the design, with no luck, but the space between the strips is the key to it. maybe sigle burner setups could be made smoke free with some suitable modification using this idea.

quote:

Originally posted by chewlikehell:
Guys, I remember from when I was a youg fella, that some "space-heater" type wood fired heaters, had a (vital component) lattice of copper strips located above the firebox. The principle was that the copper (4mm gaps) would heat up enough to burn any residual value out of the smoke before it entered the chimmney. In my area the most common firewood was sappy pine, so these heaters were the best way to go. I tried a search for the design, with no luck, but the space between the strips is the key to it. maybe sigle burner setups could be made smoke free with some suitable modification using this idea.

A catalytic process?

Or just heat retention like the upper bowl.

Tim;
Mother Earth did not come up with these mods, it was Sanders on his own, after looking at a few weaknesses in the ME original design.
Bruce Woodford improved on it by introducing forced air although it still left the original burner design lacking.The inverted bowl did away with most of the problems while using WMO but was not tested at length with used cooking oil. You have taken it one step further by introducing the double bowl design, one that I personally like beaucoup.
Sanders took the MEN furnace out of the dark ages but you have tweaked it to an even higher degree of efficiency. Take a bow. It may not yet be perfect and I am sure there will be other improvements made, but the inovative ground work is laid out now.

Murphy -- I will think about this, right now I don't know just how to proceed. This bowl burner principal requires a blast of air from the top to flow down over the hot oil and blow the vapor out across the bowl, swirling it might help somewhat but I suspect if the air is moving too fast the fire will simply be blown out. Excess air also cools everything down so vaporization is negatively effected, everything is a compromize. I will give spinning air a try using a twisted metal strip inside the combustion air inlet tube.
Another test will be to try adding a piece of perferated metal someplace so it gets hot and the smoke has to pass through it, hopefully this will burn off more of the smoke. Possibly placing a couple inch high strip of this around the outer edge of the bowls so the smoke is blown through it, this should both heat it and pass most of the smoke through it.
Kerosine wick heaters have several layers of SS screen and perforated metal above the wick just for this purpose.

I hate to complicate the cleaning of the bowls by adding more pieces, may be able to make the perforated screen set loosly around the edge of the bowl so it can be simply lifted off of the bowl for cleaning.

Legal -- I'l have to dig out my old mother earth magazines, from memory I was thinking the original MEN design used the center combustion air inlet and placed the fuel drip fuel feed tube inside it. There burner was some sort of a cumbersom type of pot burner that was a pain to clean.

The weather cooled down today along with freezing rain, forecast says it will be getting even worse with up to 10 inches of snow, so I fired up the stove in daylight, there is a bit of black smoke from the chimney when burning engine oil, not a lot but a visable amount, I can live with it for now. I will burn veg tomorrow and see how that does. Based on the house temps just now it feels like I will have to push the fuel feed well above the 1 qt/hr tonight.

Motor oil also makes a bit of soot in the burner box before everything comes up to temp but most of the soot burns away once the heater has been burning for an hour or more.

Tim,
Distribute the air.. Don't just blow it straight into the fire.. Deliver it in a distributed way that lets the fire feed off it instead of being blown away..

50 small holes bleeding small streams of air is MUCH better than 1 big hole blowing a large stream.

How about running a pipe horizontally directly through the center of your bowl (from one side to the other about 1 or 2 inches above it)
Drill small 1/8 inch holes all around the pipe for its entire length over the bowl. A 1.5 inch pipe would be good for a 10 inch bowl..
Blow air through the pipe.

A better way would be to bend the pipe.. Make a circle out of it and bleed the air in from the sides. All sides at once.. this forces the fuel and oxygen to combust in the center.

Get ready to melt your stove..

The point with the copper strip lattice mentioned in my previous post, was that at the critical distance of seperation of the thin plates, the smoke would give up any remaining volatiles. Originally developed to allow people to burn pine wood, without gumming up their chimmny stacks. The seperation is the vital thing, I was advised years ago, that a fraction of a millimeter closer or further apart would not work. The stoves I remember used to burn all night on 3 or 4 pieces of wood, and only need to be cleaned out once in a winter.

Murphy -- That is all true and works as you say but only if the fuel is already gasious, You have to heat heavy oil somehow to get it to vaporize before these techniques can be applied unless you use another fuel source for startup heat or some sort of multi-step startup. I don't burn the stove 24/7, it only burns when I am in the shop so I have to lite it at least once a day, pouring in a couple ounces of diesel and walking away with a lit stove is prefered rather than some long involved heat-up then switch-over procedure.

Dripping the heavy oil onto a hot surface is the simpelest way to vaporize heavy oil but if you are using this same oil as your vaporizing heat source the combustion is always going to be a bit dirty.

For the simplicity and ease of operation even during power outages (4 hour one last night) I can put up with a small amount of smoke from the chimney and 5 minutes a day of maintanance.

There are limitless veriables to try with this heater, once I get a bit of time my first test will be to increase the diamiter of the air passthrough hole in the center of the upper bowl to get more air to the lower one, should help reduce the smoke from the lower bowl a bit.

I want to spend time now getting the old oil-o-matic syphon-style gun type furnace burner going on heavy oil. Most of the required combustion air for the flame comes directly from the syphon style spray nozzle so they don't require the extra heat-retention swirling air spoken of on the other burner discussion. This burner unit does have a squirl cage blower and a heat retention head but it actually burns cleanest with the fan's input blocked completely off, running this burner on fuel oil shows that adding air through the retention head blows the flame apart and causes a lot of smoking flying oil droplets rather than the nice compact cone of flame that it makes with the excess air blocked off.

Chew -- I will do a bit of web searching on the copper strip idea. Probably easiest to just buy one of the modern catalytic exhaust flue inserts, they do exactly the same thing only they use a porous ceramic brick with some sort of catalyst infused into the ceramic to help initiate burning the smoke. not cheap but available.
I don't mind a bit of smoke myself, a lot cheaper that way.

Tim, thank you for chronicling your burner project. The snow is falling here again, I shouldn't fret it as we need the moisture, but I managed to neglect my shop and now I have no heat. I belong to yahoo groups wastewatts and altfuelfurnace, as if joining a group was going to warm my workplace.
On top of my lack of action, I just now found your thread, I need to reread the beginning. I am trying to visualize what you did, it seems like your design is quite a bit simpler than the Babbinton ball or Turk burner. I like that you use natural draft instead of the squirrel cage fan or compressed air.
If I understand correctly the fuel delivery system is the only moving part. Very nice.
Also, my space to be heated is so full of drafts that I am considering open and exposed flame, no chimney.
Have you made any drawings or took pictures of the burner? Are the dishes dome on top or edges up?
Thanks for everything.
Brian Rodgers

Its all one big trade-off between efficiency and simplicity.

Tim's double bowl is very simple, easy to make, and generates lots of heat... but it does so at the expense of requiring more fuel, lots of routine maintenance and a smokey exhaust.

More complex designs burn with a hotter flame, require less fuel to generate the same amount of heat and are smokeless (or should I say smoke less).. But they do so at the expense of complexity, cost, and more things to go wrong.

Its just a big trade off game. It all depends on what you want out of the heater..

I finally got a chance to test out my burner friday night... It was the first cold and wet snowy weather we've had since I had it hooked up and stacked out properly. I'm in an uninsulated block building (with lots of cracks in the block), wood roof with open trusses, and two large garage doors.. about 1500 sqft total space including 18 feet at the roof peak.. The heater brought up the temp in the shop from 37 degrees to 53 in about an hour. There were strong winds outside and you could feel it blowing right through the walls.. I'm still making adjustments.

sounds like your burner is doing its job murphy but I think the simplicity of build that Tim has going is very attractive. five minutes a day is not what I would call a lot of routine maintanence. less than a big wood stove. And it burns efficently enough to produce very little or even no smoke depending on the fuel. So should not be using up excessive fuel to heat. Little smoke means little wasted unburnt fuel. If a lot of heat is escaping up the chimmeny then that is a seperate design problem to be solved. The basic burner is still a great trade off between simplicity and efficiency.

Boss;
The basis for the modifications that Tim has done can be found here.
Sanders did a bang up job on improving the original MEN (Mother Earth News) furnace, and our very own TimCook took it a step further for what appears to be yet another improvement on an already great upgrade.
This one is a "must-do" for sure. I have access to all the basic necessary parts; water heater, tilling disks, oil...
For those familiar with the original MEN furnace, it required a definetly more complicated system to operate and still needed more cleaning that this new and improved version does. This new design, what we can call SandersImproved, can be done by almost anyone (which is why I am confident to have a go at it), and given that many of us could use a simple design,simple to maintain, furnace, this fits the bill.
For those who are more mechanically inclined or have above average technical skills this may be a little too simplistic, although that is not the majority.
I now WANT to try my hand at this.