Brad -- Yes, I still have the barometric draft control unit in place. It definatly does reduce the surges of air passing through the stove during high winds, this has to help. I am still having flameouts even with it installed but I don't think these flameouts are being caused because of flue draft issues now.

I like the control that two dampers allow. I set the combustion air damper to control the AMOUNT of air to the burner and use the flue damper to control the VOLOCITY of the airflow through the stove.

3-4 inch combustion air inlet -- I have 3, Sanders said 4 worked better because it allowed more air at a slower volocity, On my next version I will go 4, it won't work any worse and will at least give more info to see what does work best. I used 2 inch diameter auto exhaust pipe for the combustion air inlet on my double-bowl woodstove insert, it works fine for this specific burner. After burning this all last winter the bottom of the tubing has burnt away considerably but the heavy 3 inch pipe that I used in the propane tank burner shows almost no eroding from flame.

Center flue pipe -- This should be fine, the exhaust flue out the back has me wondering how much soot will end up on the inside wall of the burner tank above the flue outlet. Murphy brought his flue out about half way up the tank on purpose, I assume to trap heat above the outlet so it had more time to transfer heat to the tank, sounds good, but his burner does not produce any soot so not a problem. I have been considering how to bring the flue out on my next burner, I have considered bringing it out about a third of the way down the side of the burner tank but also adding a fairly large removable section on the other side of the tank to allow access for de-carboning if it becomes nescicary, haven't made my mind up about this yet.

Flameouts -- I think my problem now is with a TOO EFFICIENT burner design. I think what is happening is that the bowl-inside-a-bowl double container burner concept is capable of vaporizing oil faster than my low fuel feed rate drips it into the burner. This burner design allows a lot of air to be fed to the burner without blowing it out, this extra air produces a much more efficient burn of a higher brigh yellow, even bordering on white, burn, this keeps the floor of the inner bowl very hot so it vaporizes the oil very well. When I have the burner set for bright yellow flames I can look through the peep hole in the stove and see the bottom of the inner bowl, it has a very thin layer of oil boiling over a good bit of the surface, just how much of the surface depends on the drip feed rate. At this bright yellow setting I can see the bowl bottom clearly and watch the drip hit the bottom and see the thin boiling oil very clearly, when I set the burner for orange flames I CAN NOT see the bottom of the bowl at all. I need to make a comment here - liquid oil does not burn, vaporized oil does. -BUT- even vaporized oil needs to mix with air before it will burn. I don't have this totaly straight myself yet - but - since I can not see the bottom of the bowl when making orange flames I suspect that the oil vapor is burning very near the surface of the liquid oil but when burning with yellow flames the oil is being vaporized at a much faster rate, this fills the lower bowl area with much more vapor but the fast creation of more oil vapor does not let air penetrate deep into the bowl so the flames are not actually burning until the oil vapor and air mix close to the top of the bowl. I think this is why I can see the bowl bottom with yellow flames but not with orange flames. -NOW- why orange flames make much more coal than yellow flame is something I have not exactly figured out yet. I assumed the coal was unburnt and baked heavy components of the oil, it may be that the higher temps caused by the yellow burn actually vaporize even these heavier components so that even they get burnt cleanly, don't know myself but the yellow burn is many times cleaner than an orange burn. Upon inspecting the burner bowl after an yellow flame flameout the bowl has ALWAYS been absolutely clean and dry, no fuel in it at all except for the last couple drops from the pump just before the flame sensor shut it down. -- UNFORTUNATLY, I can't keep a yellow burn from going out. I finally actually saw it happen the other night, the burn simply made a short "ffttt--tt' sound and went totaly and instantly out, just like turning off a light bulb. I suspect this has to do with the flame actually burning only near the top of the burner bowl rather than deeper down inside of it. If this is the case it would not take much of a disturbance in the balance of either the vaporized oil or the combustion air for the burn to simply stop. If I run the burner with an orange color it stays lit continuously but burns with more smoke and makes a bit of coal, yellow burns MUCH cleaner but goes out. yellow will burn for several hours before going out, I suspect as the stove heats up over these several hours the burner vaporizes oil at a somewhat faster rate due to more heat in the stove and the burner, at some point the oil gets vaporized faster than it is dripping in, this leans out the fuel/air ratio such that at some point the stove simply stops burning due to a lack of fuel, but - just before this point is reached the burner is actually running at its most efficient lean fuel ratio FFTT--TT, out it goes.
The 2-quart burner has 4 times the bottom surface area of the 1-quart burner, This vaporizes fuel way too fast for the amount of heat I need, I have dropped back to testing the 1-quart burner for now, it still vaporizes my low fuel rate way too fast with a yellow burn. To keep it burning I have the combustion air damper no more than half open and the flue damper closed down to give a mid-orange color with a slow flicker and the sound of the fuel vaporizing is still a continuous sizzle rather than hearing each fuel drop sizzle. -- More testin..

1/4 inch pipe "T" flame sensor viewing port -- Worked better but still not done. The "T" is almost 2 inches end-to-end, this restricts the light to a nerrow enough image that I removed the reducer from the outer end, the sensor sets about another 1 1/2 inches away from the end of the "T" and the flame image is only about a nicely defined 3/4 inch circle. Since the restriction is removed from the outer end I don't think there is any advantage to using a "T", a straight short pipe nipple should work as well. I had this 1/4 inch "T" clog with soot once over the last week, better than before but it still put out the flame in the middle of the night. The next test will be to use a short 3/8 pipe nipple, probably be about 2 inches long, This larger diameter opening should let even more air through to keep the soot blown inside the burner rather than clogging the opening. This won't let enough air in to disturb the burn as I am running the 3 inch diameter combustion air inlet damper open at least half way anyway. I did not get the hole for the viewing opening and the hole used to mount the 1/4 inch chunk of all-thread, used to hold the flame sensior, aligned exactly, had to "reform" the all-thread a bit to get the sensor in line with the flame image. This is still not correct due to the sensor being mounted in the end of the 1 inch long brass tube, since the flame image is now being see through a length of larger pipe I think I will remove the 1 inch brass tubing and mount the sensor directly into an opening in the phynolic mounting piece, I am even considering mounting 3 sensors rather than just the one. Placing 3 sensors about a 1/4 inch apart, running vertically along the phynolic mount, will insure at least one of them will see the flicker of the flame and The alignment won't be as critical as it is now. The 3 sensors will simply be wired in paralell, which ever one sees light will short the two sensor wires together and keep the pump running, if more than one sensor sees light everything still works the same.

I have been out for a couple of days but managed to get back to it yesterday. This is what I have done . I found a 3" brass fire hose/hydrant cap and set it upside down inside the burner I have already in place. I thought this would be a good idea because brass holds heat very very well.

With this in place I started the burner as usual with diesel and started my drip at first it seemed not to make any difference then I started to close the flue damper. As the heater started to really heat up I noticed that the oil and left over diesel started to boil right on the side of the brass cap. This in itself proved that the brass absorbs heat better. As the pool around the brass started to decrease the oil drip now is boiling as soon as it hits the cap. This is the most exciting thing I have seen so for so I ran outside to check the flue and as I had expected hardly no smoke just heat wave coming from the flue.
This to me is something I have not seen before.The heat build up in the furnace is getting very very hot, so hot that the oil line that I just previously wrapped around the flue (about 6 wraps) is staring to get hot to the touch and is now starting to spray out of the pipe on to the brass so I had to stop the drip momentarily.
I allowed it to cool for a few minutes and restarted with a very slow drip and man the brass seems to make all the difference for me.
It would be worth a shot for you guys to try it.
I will try to take some pics of this cap so as you can see it although you can use any brass and I would think any shape this thing is about a 1/8th inch thick.
I also cut more openings in my case to allow more air to blow around the furnace assembly and actual saw temps of 210 degress with all 3 holes cut "wow".

This message has been edited. Last edited by: Scott C.,

merry christmas all.....pictures scott pictures.....tigman

Well - It looks like air pipe outlet to burner distance IS important -- The double insulated bowl burner seems to work extremely well and will allow a hot bright yellow burn, this high vaporization heat reduces smoke, coal, and soot, but how to keep it burning continuously. The longest I have had this burner burn has been 7 hours before it flames out.

It seemed like the burner was vaporizing low fuel rates faster than the fuel was being added -or- The air was moving too fast through the stove and blowing out the layer of oil vapor that is burning close to the top of the burner bowl -so- What to change next? -- I decided to move the burner assembly a bit farther away from the end of the combustion air inlet pipe. I moved the burner assembly arbitrarily 3/4 of an inch farther away from the end of the air pipe, the upper edge of the burner unit is now 5 inches below the end of the air pipe outlet and the bottom of the inner burner bowl is 7 1/2 inches below the end of the air pipe.

WOW - What a differance, the burner ran for 4 days continuous, apparently this small extra distance is enough to allow the blast of air coming from the end of the air inlet pipe to expand outwardly, this reduces the air vilocity enough to not totally disturb the burn.

The first two days of this 4-day burn was during the highest winds we have seen is several years. The wind was literly howling through the trees for almost 2 full days, the weather report said 30-40 MPH sustained winds with 60-70 MPH gusts, I know it had the barometric draft control damper dancing between wide open and banging totaly closed, mostly it quivered from about 1/4 to 1/2 open all the time. The only time I saw any observable change in the burner flame was when the damper was standing totaly open, even being totaly open the wind was creating enough edditional draft to cause the flame to flicker much faster but it ws not enough of a problem to cause any flameouts.

For the first 2 days I was burning more fuel than usual, about .4 G/h (about 3 s/r of pump), I had the dampers set so the flame was burning with a very bright yellow flame, the combustion air damper was over 3/4 open and the flue damper was set to half open (45 degrees from fully closed), unfortunatly, by having the flue damper set to the half-open position a LOT of heat was going up the flue rather than heating the house, the outer burn tank temp was running about 200 to 250 degrees with a fan blowing across the tank. The burner was running very clean but not heating ther house as well as I hoped.
For the last 2 days I reduced the fuel feed to about 1/3 of the prior amount, down to .12 G/H (6 sec/rev of pump). Since the fuel was reduced by about 3 the amount of air needed was also reduced, I was able to set the combustion air damper to be open by one half of maximum and the flue damper was closed down to about 3/4 closed (22 degrees from fully closed). This produced a bit darker yellow flame but it still burns with much less soot and smoke than an orange burn but it does produce a bit more soft coal deposits in the burner bowl than a bright yellow burn. Even with this lower fuel setting the burner tank temp was still about 200 - 250 degrees f, I attribute this to the dampers being more closed so the hot internal combustion gasses had more time to transfer there heat to the burner tank rather than carrying it's heat up the flue.

This lower fuel rate, along with a considerable reduction in soot, is where I think I will run the burner. With an orange flame I would produce about a 1 to 1 1/4 inch deep layer of soft fluffy soot flakes around the outside of the bottom of the burner assembly after a couple days of continuous burn, the current mid-yellow burn for 4 days produced only maybe a quarter inch of this soft soot.

The burner finally went out after burning continuously for a full 4 days, this was a full day longer than in the past. The burner went out due to burner bowl deposits creating sort of a shallow "volcano" cone structure in the burner bowl, this apparently disrupts the fuel vaporization or the air flow, don't know for sure, but this "going out once a volcano is produced" has been the norm in the past. I will simply shut down the stove for a few minutes every 3 days and swap in a clean inner burner bowl, only takes a couple minutes once the old bowl stops smoking, the stove never even cools off so it re-lights with very little startup fuel.

I am willing to accept this small amount of soft coal and reduced amount of soot in exchange for burning a much smaller amount of fuel while still producing the same amount of heat for the house.

This picture is of 4 days of soft coal in the 1-quart burner bowl. The picture does not show the amount of coal well but you can sort of see the inner edge of the volcano's center opening, the soft coal starts at the outer edge and builds inwards and upwards til the flame goes out. the inner edge of the coal crater is about 3/4 of an inch above the bottom of the bowl. The crud is not solid from top to bottom, it is hollow underneath with only a thin crust over the top. This crud is pretty soft and will crumble out of the burner with just a few taps with the end of a screwdriver blade.

3.JPG (58 Kb, 41 downloads)

I also made changes to the flame sensor sensors and the viewing port. I opened up the tank viewing port by screwing a 2 1/2 inch long 3/8 pipe nipple into the side of the tank. I also removed the 1-inch length of brass tubing from the phynolic sensor mount, I also added a second sensor element to the phynolic mount. By placing the sensor devices directly into the back of the phynolic mount they see the flame without having to be precisely aligned with the viewing opening. The 2 1/2 inch length of pipe produces about a one inch diameter circle of flame image on the front of the phynolic sensor mount.

I also removed the heat shield from in front of the sensors as this setup allows the phynolic mount to stay fairly cool, cool enough to hold your hand on it continuously.

So far, the 3/8 pipe nipple has stayed free of soot, it's 1/2 inch diameter inner opening allows a good bit of air to flow inward through it, hopefully this will keep the soot from building up. The current burner setup ran for 4 days continuous so the sensor ran at least that long wiithout causing a false fuelpump shutdown.
even if I have to clean soot out of this every 3 days when I change to a clean burner bowl I can live with it.
This picture shows the new flame sensor assembly and viewer port.

flame_sensor_and_view_port_with_tape_measure.JPG (26 Kb, 32 downloads)

This picture shows the back of the phynolic sensor mount with the two sensors superglued in place.

duel_sensors_in_phynolic_-_flame_through_pipe.JPG (48 Kb, 25 downloads)

One thing I found during the high winds - I had the weight on the barometric damper set to it's mid-point. During the high winds I was seeing small puffs of smoke coming from the cracks in the stove when the damper would move open, the smoke would stop once the damper closed. From past testing of manualy setting the flue damper I know that to keep smoke from coming out of the stove it is nescisary to open the flue damper more so air is sucked INTO the stove rather than smoke being blown OUT of the stove. To have the automatic damper work in this same manner it was nescisary to INCREASE the weight on the damper so it did not swing so far open and cause the suction from the chimney to be reduced too much, the reduced chimney suction causes the pressure in the stove to be increased enough to push smoke out the cracks in the stove.

One other comment -- I did not know quite what I was doing when I first put this stove together, I now know that one error I made was to run the fuel supply tube down along the inner wall of the combustion air inlet pipe, this causes the fuel drip to fall to one side of the center of the burner bowl. The burner bowl needs to be located directly under the center of the combustion air pipe or the flame in the burner bowl is not uniform, due to this fuel tube location oversite the current fuel drip drops off-center into the burner bowl. The drip should fall directly into the center of the burner bowl to keep the fuel vaporization uniform. In the future I will relocate the fuel drip tube to the center of the combustion air pipe. I wiil be sure to center the fuel feed tube in the combustion air inlet pipe on any future stove project.

I think this is about it for any current burner development, everything is working well enough to be acceptable for now. I think the next testing will have to due with baffles inside the burner tank to move the hot gasses out closer to the burner tank so they can transfer heat to it more easily, hopefully this will allow a bright yellow burn but still keep the heat in the stove rather than having it go directly up the flue.

This picture is of the position of the weight on the barometric draft control damper unit. This setting is about at the .5 water columb point I think, it is about 5/8 of the way between the lightest .2 end of the adjustment slot and the heaviest .8 end.

draft_control_weight_position.JPG (30 Kb, 22 downloads)

This shows the automatic draft damper in a "T" above my wood stove.

damper_in_T_-in_chimney.JPG (27 Kb, 30 downloads)

Just for fun - This shows my home heating center, yep, I'm a hermit.

heating_center_-_both_heaters.JPG (22 Kb, 56 downloads)

so tim you say 1qt burner are you back to the second setup in your pict of all 3....not using the 2qt dog food dish?? I live alot like you HERMIT Jeff

Correct - I am now burning the 1-quart steep-sided dogfood burner bowl that sets entierly down inside of the outer container.

The 2-quart burner vaporizes fuel way too fast for the small amount of heat that I need. It can burn extremely clean but I had trouble with it flaming out due to fuel starvation with my small fuel feed, I suspect it was vaporizing the fuel faster than the drops were hitting the burner, don't know for sure.
This 2-quart burner may work ok now that I have increased the distance from the combustion air pipe but the 1-quart burner is working fine for now. I may do a bit more testing of the 2-quart burner just to deturmine if the extra air feed distance made any differance with it also ?

The 1-quart burner so far has burned fine with a fuel flow of well below a pint an hour or with as much as a half gallon per hour, I suspect it will burn well even at a lot higher fuel rate.

Hey mind if i bust in? I have to buld one of these. Anybody know if a snowmobiele oil pump would work to deliver the sticky stuff? I dont know if it would pump enough???

harry3 -- I have not read of anyone using any pump from a snowmobile, looks like you will be the leader researching that one. The Suntec pumps have been pretty well developed and the modifications documented for use as slow speed metering pumps(links close to the front of this discussion)so I will be staying with these for most of my fuel pumping projects.

SECRET TO THIS BURNER FOUND -- I think. -- The secret to the superior vaporization chericteristics if this burner design IS -- FUEL DROPLET SPLATTER --

I spent about an hour peering through the stoves peep hole at the bottom surface of the burning bowl last night.

I had just re-lit the burner a few minutes before and took a glance through the peep hole just to verify everything was burning ok. To my surprise it looked like there was about a quarter inch of liquid oil covering the bottom of the burner bowl, this could not be possible at the small fuel rate that the pump was set for, what was I seeing? It took a few minutes before I figured out that I was seeing an optical illusion, what looked like a pool of shimmering oil was actually the reflection from the flickering flames reflecting off of the shiny SS bottom of the bowl (another mystery, the bowl bottom is always dirty black after cleaning out the crud but all the black apparently burns away once it begins burning and the inside bottom of the bowl looks like normal new shiney SS through the peep hole?).

In reality - the bowl bottom is absolutely dry when burning except for the point where the fuel droplet hits it, there is about a quarter inch wet area where the fuel feed drop hits the bottom of the bowl(this may also be an optical illusion though, could be seeing the reflection of the falling fuel droplet while it is still falling?). Watching the surface of the bottom of the bowl closely I finally was able to see small ragged sorta circular patterns come and go, these looked like tiny coffee stains on a table, you could not see anything but sort of a thin pencile-line type thing around there outer edge, I finally decided that I was seeing the outlines of hundreds and hunderds of very tiny droplets of fuel hitting the hot bottom of the burner bowl. I think what is happening is that the fuel droplet from the fuel feed tube is sort of explosivly blown apart as it hits the extremely hot dry bottom of the burner bowl, as the droplet hits the hot metal the bottom surface of the droplet is instantly vaporized, the expanding vapor can't move downward against the solid metal so it violently pushes up against the liquid oil drop, the oil drop has fallen about 10 inches from the end of the fuel feed tube so it moving downward at high speed, the combination of the fuel drop moving downward at high speed and the vapor moving upwards at high speed pretty much tears the big droplet apart and blows the tiny chunks of it all across the interior of the burner bowl, these tiny droplets rain down all across the surface of the extremely hot dry metal bowl bottom and are almost instantly vaporized. Watching this happen I see outlines of tiny droplets smaller than the head of a pin, these shrink to nothing almost instantly, I also see larger outlines, maybe an 1/8 inch in diameter, these appear, shrink, and disappear, all in well under a quarter second. I don't actually see the tiny oil droplets, just the outline of there outer edges, I suspect they are very thin and I am only seeing a shadow created by the outer edge of the extremelly thin oil film, don't know. I don't see anything like "boiling", the outline simply appears, shrinks, then disappers - it is immediatly replaced by another shrinking outline, over-n-over, I see this going on over the entire surface of the burner bowl bottom as well as on the steep sides of the bowl, LOTS of hugh-speed vaporization goin on..

If I open the flue damper just a bit the fuel droplet outlines shrink away a bit faster and the flame changes to a brighter lighter yellow color, if I close the flue damper a bit the droplet outlines take a bit longer to disappear and the flame changes to a darker yellow color.

This is with a fuel feed of about a pint/hr, watching the bowl in the past when feeding more fuel seemed to show an extremely thin film of boiling oil over a large part of the bowl's bottom surface -but- I will have to look at this again now that I know there are also optical illusions going on.

Ok now your freakin me out starting to sound like the 60's dude...quit stareing at the bright light...but thanks for the observation...I'll have 1 less beer tonight..LOL Jeff

O.K. Im back and I finally have some pics.

1. Here is the burner with the brass cap in place this is after a 48 hour straight burn with no flame outs . I turned it off to allowed to cool and took pics. No cleaning done.



2. Here is what one of these brass caps looks like new. I removed the piece on the cap that holds the chain I dont think that was necessary.


3. Here is what everything looks like in place its kind of hard to tell but you get the idea.


Well this is the set up that works best for me I can really get alot of heat with low flow and have great control. Very low smoke and no flame outs. You can hear the oil sizzle adn atomize right on top of the brass. I am trying to do a video so you can hear it and see it.

Ok cool you went ALL dog dish..whats the secret agent wire coming from the side of heat chamber over burner?? I got my metering pump today 275.00 delivered ouch...but then again 3000.00 for my first veg oil conversion for my truck paid for itself in 4 months easy...Jeff

Tim, I believe we are both on the same sheet about the baffles .I am extremely happy with my burner at its present state and was thinking about inside baffles.

quote:

I think the next testing will have to due with baffles inside the burner tank to move the hot gasses out closer to the burner tank so they can transfer heat to it more easily, hopefully this will allow a bright yellow burn but still keep the heat in the stove rather than having it go directly up the flue.

Let me know how yours goes.

It was the anode rod from the water heater tank I just bent it out of the way.

Scott -- Were you burning veg or used motor oil during the 48 hour burn? What was your fuel rate per hour?

Looks good, another bowl-in-bowl burner that looks like it is working.

Baffle -- Thinking about this a bit more, I think I will try placing a cylinder that is a couple inches smaller in diameter than the inside of the burner tank vertically inside the tank, this would force the hot gasses to flow up between the walls of the two cylinders so the heat would be in much more direct contact with the inside wall of the burner tank all the way from just above the burner up to someplace close to the flue outlet. The 100 pound propane burner tank is about 13 3/4 inches across on the inside, I have a portion of a small air compressor tank that is 12 inches across, this air tank still has one end in place, I will cut a hole in the center of the end that just lets the combustion air pipe pass through the end, hopefully I can weld a coller around the hole through the end of this air compressor tank insert and simply clamp it to the combustion air pipe to hold it in place, this would also let me easily adjust it up/down inside the burner tank. The big open upper end of this insert will run up to within a couple inches from the top of the tank, may eventually be able to add a second cylinder inside this inner one to direct the flue gasses back down into the center of the insert to act as a supper heater for the flue gasses and somehow ignite these before they exit the burner tank, burning any leftover flammables (smoke) in the flue gasses in this afterburner, this would pull every last bit of heat from the fuel and pretty much eliminate any smoke.