I was hijacking Murphie's discussion (here) by mentioning this burner project there, it should be seperate.
I am testing an old Williams oil-o-matic burner for use with veg and/or used motor oil. this is only in the very early stages of testing, only a couple hours so nothing definitive yet. I added a preheating chamber to the fuel supply that I hope will allow me to burn the heavier oils in this old syphon-style gun burner.
The following entries were copied from that discussion --
Murphy -- You are right about used engine oil being hard to get to burn clean. I fired up my old syphon style gun burner today for the first time, burns veg great but it won't burn engine oil or even a 50/50 mix of veg/engine without smoking a LOT.
I was a bit surprised that it did not take nearly as much preheating of the veg as I had expected from reading the altfuelfurnace forum. I had the pre-heat set way too high initially (around 500 watts of continuous pre-heat, don't know the temp yet) and did experiance boiling/outgassing in the pre-heating chamber, this caused the flame to pulse on/off as first liquid, then vapor, was fogging out of the burner nozzle (may have still had a small amount of regular fueloil in the preheat chamber). This unit has the standard fueloil furnace burner style electric spark ignition and it is designed to run all the time so the flame reignited whenever there was adiquate fuel fogging from the burner nozzle. I dropped the preheat wattage down in incraments and finaly got a nice continuous burn (about 250 watts of continuous pre-heat), plenty of burner heat output (burnt the silver paint of the outside of the propane tank burn chamber in just a few minutes), fairly short flame (no fire shooting out of the top of the burn tank anyway) and absolutely NO smoke. I could turn the fuel cutoff solenoid valve on/off and get a perfect instantanious cut off of the flame, it re-ignited effortlessly and cleanly every time, did not even get a puff of smoke when it ignited.
NOT EVEN CLOSE WITH USED ENGINE OIL -- I again initially had the oil heated way too hot, got lots of outgassing and flameouts. With this high preheat the oil burns without smoke, but with a VERY long flame, whenever it actually burnt, just could not get it to burn continuously due to the outgassing going on in the per-heat chamber. I turned down the preheat to about half of the heat used for the veg (100-125 watts) and finally did get a continuous burn but it was very smokey and put out very little heat.
I had placed a needle valve in the burner fuel supply line in the hopes that I could use it to throttle the size of the flame, sort of worked but not reliably, I found that if I cut the engine oil fuel completely off and then back on using this valve I could get a clean burn for a couple seconds when first turning the fuel on. This burner unit has a built-in fuel pressure regulator to feed fuel to the syphon-style burner nozzle, I assumed it was a "demand" type regulater since it was feeding a syphon-style nozzle but it turns out to be a standard pressure regulater that it set to a very low pressure (1/2-1 pound ?, fuel barely dribbles out of the fuel hose to the burner nozzle when it is disconnected), turning the fuel off/on allows the pressure to build up a bit when off, this slightly higher pressure seems to be needed to get the used engine oil to fog efficiently out of this burners nozzle, unfortunatly there does not appear to be any practical way to adjust the regulators output pressure ?
Even if I could reset the pressure to get a clean burn with the engine oil the flame is so long that I get about 2 foot of fire shooting out of the flue pipe opening in the top of the propane tank burn chamber, not exactly what I was expecting.
This old oil-o-matic burner does fine with vegoil so it will do for now. I will do a bit more testing burning engine oil but it does not look practical in this specific burner but this was only the very first testing.
I will simply place a small fan behind the smooth burn chamber tank and blow air over it for now, not as efficient as all the little fins but It will be interesting to see how it does, I can always add the fins, could even make up a water jacket for the tank rather than using it to directly heat air.
Another entry copied from murphies discussion -----
This burner unit is an old Williams commercially manufactured fueloil furnace burner, they have not been made since the early 70's. This burner is not a drip-style burner, it is a gun type burner using a syphon style burner nozzle. It uses an actual rotary fuel oil pump driven by the blower motor and also a vane-type air pump, both pumps are built into the same housing. The fuel pump is similar in concept to a modern suntec fuel pump, it can be configured with a fuel return line back to the fuel tank or for a single supply line only.
The regulator is a standard diaphragm design but the body is a custon cast aluminum housing made to these burners so is not easily replacable by any other style regulator.
The air pressure is not yet easily tweekable as in the factory configuration it is controlled by a simple pinhole as the pumps air intake so it is not yet adjustable. I eventually intend to replace this input with another needle valve but have not gotten to it yet, wanted to get it burning before making any extreme mods.
I will start another discussion about this burner and will add pictures eventually.
Murphy -- Long flame --
I have tweeked both the additional flame retention air and the fuel amount, nothing helped. I can not yet tweek the atomizing air and I Increased the flame retention air (from squrle cage blower), this did not seem to help the flame length or the smoke but it did keep the flame from relighting after a fuel shutdown and restart. Tried adjusting the fuel during this restart period and it never would relight. I reduced the fuel retention air and got it burning again, adjusting the fuel amount with the fuel needle valve made a bit of differance in the flame size but once the flame dropped back inside the burner tank it still created huge amounts of white smoke (yes, way excess in fuel, could even smell it). Lots of testing to go on here yet but I suspect it has to do with the larger size holes in this burners syphon nozzle. It has three large 1/32 inch holes.there are likely producing oil droplets that are too large to atomize the cooler preheated engine oil well, the veg wants to be heated considerably warmer (twice as warm) than the engine oil so it should atomize better even if the different type of oil droplets are all the same size. Can't do much about the nozzle hole size since there are no parts available for this burner except scavenging other old burners. This nozzle says it flows 1.4 G.H based on fuel oil, from testing it flows a LOT less than this on thick oil, need to burn it more to get an actual burn rate.
BTU -- I have not seen these numbers, everything I read on the used oil burner web sites say used engine oil is the same as fueloil at 140,000 btu/Gallon, veg is usually shown as 120,000 btu/gallon although this depends on just what type oil it is EnergyLogic website BTU tabkle is here).
There is also a differance in used engine oil, my oil is mostly from farm tractors and my truck so it is mostly thick oil, 15W-40 or 15W- 50 type oil. modern cars use mostly much thinner 5W-20 oil, these different weight oil will have quite a differance in thickness that will directly affect flow and atomization even when warm.
Flame length -- I currently have the complete heater raised up on a work platform a couple feet so I can't see down the flue outlet yet, I will set this down tomorrow and hopefully I can tell the actual (estimated) flame length. I don't yet know just how long the veg flame is but it stays entirely inside the burner tank, used engine oil shoots flame a couple feet out of the flue outlet when burning with no smoke (wont due this for more than a couple seconds), any time the used engine oil flame is contained inside the burner tank I get LOTS of white smoke indicating way too much fuel. Simply turning down the fuel needle valve does not eliminate any of the smoke but it does reduce the amount of flame. Lots of testing and tweeking to try on this unit yet, unfortunatly I need to use it for house heat shortly so may have to live burning veg for this winter and tweek it later
When you refere to "combustion" air is this the small high pressure orifice oil atomizing air or is this the excess air from the squirl cage blower.
Burning veg in this burner also eliminates all the smoke, just that same shimmering hot air look directly out of the top of the burner tank flue outlet, it sure is not adjusted for burning used engine oil yet, may never do it well enough due to the nozzle hole size?
The following pictures are from an ebay sales page of one of these oil burner units.
f5ae_3.JPG (12 Kb, 110 downloads)
I played with this burner for a couple hours again today. The fuel system was full of used engine oil that I wanted to clear out so I could try burning veg again. The preheat unit holds about a pint of fuel so I assumed it would take maybe 15 minutes (?) of burning to empty it of UEO and get veg to the burner. I removed the burner tank and got the burner lit, sorta, on UEO. the flame was about 5 inches long and made a lot of smoke, I suspect this is the same way it was running inside the burn tank yesterday. I turned the preheat up/down trying to get a good flame, never got better. I ran this long enough that I could begin to smell veg burning but still never got back to the good clean burn that I had yesterday, it may require that the burn tank be over the burner unit so that there is a warm enclosed space around the burner nozzle before it will atomize the oil and burn correctly. I was doing all this outside in an effort to get the propane tank burn chamber hot enough to burn off all the paint, don't want that happening inside the house, never got it burning correctly before it got dark. The temps were around 30 deg f and it was snowing a bit with a good bit of wind so this may have kept the burner from ever getting warm enough to atomize the oil properly as there is about 18 inches between the actual burn nozzle and the output of the preheat chamber, about a foot of this is steel tubing inside the burner unit's flame assembly, the squirl cage fan blows external cold air over this tubing, that would likely have sucked a lot of heat out of the oil before it ever got to the burner nozzle. I will keep trying, supposed to get up to 22 deg f and be sunny tomorrow.
I did get a few pictures of the unit and the poor flame, I will finish out the role of film and post them here in the future.
I really think you need to figure out how to either decrease the WMO or increase air.
Burning veg oil is nice, but in my opinion, I'd rather reserve that for making bio..
Now tallow.. burn it all..
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I will keep experimenting with UMO but I have way more veg than I use, I am committed to collect it so might as well use it for heat. I don't make biodiesel as it still takes a heated fuel setup to use it in the winter so might as well save the extra cost of making the biodiesel and simply burn straight veg.
veg is actually easier for me to find locally, I have been checking around a bit about collecting bulk amounts of UMO, commercial companies like trucking companies actually prefer paying to have it picked up by a liscenced/insured waste collection company due to the "it is the generators responcibility for it forever, no matter where it ends up". They don't want the liability of giving it to an individual and getting burnt when/if that person has problems with the EPA or whoever. Even some farmers are reluctent to give up oil for this same reason. Both of the auto repair shops locally burn UMO for there winter heat and use all the UMO oil they produce from oil changes themselves, also not all that many folks change there own oil anymore because of the effort needed to get rid of it.
Veg has a lot less liability connected with it than the UMO that has been designated as a hazerdous substance, this designation can cause all sorts of fines and court problems for anyone that is not a qualified/certified/insured commercial waste oil collector, all it takes is one pi$$ed off neighbor making a phone call..
I would like to burn the UMO that I generate from my own oil changes but this only amounts to less than 50 gallon/year any more, that would be used up through a stove in less than 2 weeks so it wouldn't save all that much on the heating bills. I can mix it with veg and burn it through the double bowl burner ok, seems like the easiest way to go.
I put the burn tank back over the burner and did get it burning on veg again, may have been all the wind that kept it from burning without the burner tank in place ? Burnt it for 15 minutes, looks like it is burning about a half gallon of veg per hour, should be more than enough heat for my application.
I later drilled an additional 1/16 inch hole in the vaporizing air pump's intake assembly, hoped this extra air would help make the burner nozzle spray a finer spray, the spray is deffinatly much finer but apparently the velocity of this fog is just too high for the electric spark to ignite it, I couldn't even get it to light using a propane torch, it didn't matter how much preheat I applied, it just would not light. If I placed the torch flame directly at the base of the fog I could get about a 6 inch flame with no smoke but it died out the instant that the propane torch was removed. I will try going the other way tomorrow, the air pump input originally had 4 holes in the input, I added one more, tonight I will plug up a couple of these and see how it reacts with LESS air rather than more air. I also found an adjustment for the fuel flow amount so I can also tweek that from full-off up to about a half gallon/hour of fuel feed. There is yet another screw tweek on this unit, haven't figured out what it is for yet, also found that I can probably change the fuel regulator's pressure somewhat by either changing it's internal spring or shimming the spring, just have to try all these veriables over time.
I have to light my burner with combustion air off.
Once its burning, I turn the air on.
Seems you're doing allot of work on this stuff Tim. I'm fairly confident you are going to discover something or tweek it to the point where its working pretty dang good.
You need to get a digital cam dude!
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Too right. I keep telling him... They are so cheap and easy now.
mathematical elegance -- desired result achieved with minimal complication
Is your's the model Fifty-Ten? If so the book I have has a few good drawings on it.
I took some some photos of the basic construction of the burner assembly and burn tank, I will scan them in once I complete the roll of film. Need to get to town and pick up the pictures of the bowl burner, maybe this week end.
Played a bit more today, reducing the atomizing air did NOT make it light any better but did change the sound and apperance of the fuel fog a bit, much corser than with the extra air added. I will go back to the extra air for tomorrows testing.
With the reduced atomizing air the burner lights OK with the burn tank in place once hot oil actually gets to the burn nozzle. I have 12-14 inches between the burner nozzle and the preheat chamber so it takes several seconds to get the hot oil up to the nozzle, especially when first fiering up the 20 deg f unit. Once the assembly is hot it lights off as soon as the oil fog exits the nozzle, doesn't seem to care how hot the oil is as long as it is at least warm. I was able to hold my hand on the preheat chamber and it would still light once everything was hot, couldn't have been much hotter than 100 deg.
wish I could turn the combustion air off for lighting but this air is from the squirl cage blower that is mounted on the same shaft as both the oil and air pumps so to get fuel I also produce combustion air. For the veg to burn clean I have to almost completely block the intake to the combustion air fan, at least that seems to be the same as Murphy's unit.
I played a bit with crudely increasing the fuel pressure, this makes a BIG differance in the burn, normal pressure gives a small 10-12 inch tall flickering yellow flame even when burning normally (looks the same as normal high pressure gun burners that I have seen deminstrated), increasing the pressure just a bit gives much more heat (you can feel it instantly even through the wall of the burn tank) and the flame gets a bit bigger (longer, maybe 20-22 inches) but not excessive, the color goes from flickering yellow to brilliant solid white, The increased burn looks a lot like the pictures Murphy posted in his discussion (here), what a differance. I increased the pressure slightly by simply squeezing the 1/4 inch rubber fuel line slowly over about a half second with pliers, don't know just how much extra pressure this made but surely not all that much. I will first get the unit burning with the extra siphon air then shim the pressure regulator with a washer and see what happens. The slight increase in pressure seems to improve the fuel/air atomization a lot, it will also increase the fuel rate but I will have to live with that as this is deturmined by the size of the fuel exit holes in the burner nozzle, this is a special nozzle assembly that it not interchangable with any modern nozzle unfortunatly.
I have a second rusty pump assembly including a fuel pressure regulator so I can shim this second regulator and swap it for the existing one, would hate to ruin either one.
canola -- yes, fifty-ten. pictures only help if the adjustments are labled as to what they are for, I'll keep playing and figure it out over time - Thanks. I keep watching ebay for a manual but all they seem to have are the old advertisements, these don't help. Found some info with web searches but not any real help.
Probably should have started with modifying the more modern Wayne high pressure gun burner over to having a syphon nozzle, at least parts are available for them, this is the next burner project.
Syphon air -- i opened up all five of the 1/16 inch holes to the input of the air pump today, this makes a nicer finer fuel fog and it ignites the same as with less air but the burn seems to be a bit smoother, not as much "rumble" from the flame.
Ignition -- I am finding that when the unit is cold (outside in 20 deg f temps) I need to apply a good bit of preheat to get ignition. It takes 14 seconds for the oil to get from the preheater to the burn nozzle, and an additional 25-30 seconds of fuel being fogged into the burn tank before I start getting erratic ignition, it will flame - then go out, then do it again, for another 15-20 seconds. It will acchieve a good solid burn in under a minute, even in these low temps. Once everythig gets up to temp (no, no explosions, not even a "chuff" the burner just lights-goes out-relights-and finally attains a continuous burn. There is some gray smoke during this start-up period). After 4-5 minutes of burning everything gets warmed up nicely and the burner will ignite at the first instant the oil fog exits the burner nozzle.
Fuel regulator -- I disconnected the fuel outlet hose from this regulator and ran the pump, with the factory spring installed it output about a drip every 2 seconds. I added a 1/16 inch shim under the spring and this caused the output to pretty much completely stop flowing, may have weeped just a small film of oil. I replaced the spring with a weaker one and got about 2 drops/sec, a still weaker spring got about 5 drops/sec.
All this tweeking had NO obvious effect on the flame. It appears that this regulator unit is not realy a pressure regulator, more of a max fuel flow regulator. It limits the max amount of fuel available to the burner nozzle but does not really control the pressure directly, the fuel outlet holes in the burner nozzle are the final restriction so if the fuel is restricted to less than they can flow the fuel pressure will be low. The "smoothness" of the burn does seem best with the factory spring so I reinstalled it for now.
I have pretty much figured out all the adjustments on this burner, also found that the wierd fuel pump they use (two tiny 1/8 inch rotating pistons) has a pretty limited capability as far as fuel flow. adjusting the fuel flow to the max does not create quite the optimum fuel pressure to get the nice smooth white burn but I don't see any easy way to overcome this as yet.
This burner does seem to light up on preheated veg reliably and burn mostly clean, it does produce just a bit of smoke whenever the burner flame "stumbles" and changes burn rate, this happens continuously as it burns and a small short 1/10 second waft of white smoke exits the flue outlet every second or so, may be able to improve this by adjusting the preheat temp ? The flame changes also create a sort of "rumble" from the flame.
-- It will do for now -- it is getting installed inside tomorrow before we get hit with the 3-6 inches of snow forecast for sunday night.
Purge solenoid valve -- I have installed a 3-way solenoid valve just after the preheater, this allows for purging fuel from the burner fuel line and nozzle at shutdown. From reading, I find that one of the main maintanence points for these smaller heavy oil heaters is nozzle plugging due to polimerization and coaking. This is largly caused because the fuel sets in the fuel line and the nozzle after the hot burner shuts down, this bakes the liquid fuel into either polimerized or carbonized crud.
The more modern gun burners with syphon nozzle setups still have pretty small internal nozzle passages, folks describe needing to clean these occasionally. Gun burners that spray only high pressure oil through the nozzle plug up even more often, every one or two months, these nozzles are not cleanable so get replaced with new ones, cost 5 to 15 dollars each.
This is the feature that interested me most about this old oil-o-matic burner. It's nozzle is pretty cleanable, it's inner nozzle assembly has three 1/32 exit holes for the fuel, these holes are in the bottom of small machined channels, the syphon air passes through these channels and mixes with the fuel. A brass cap, with an 1/8 inch hole in it's center, screws over this inner assembly, the fuel/air fog sprays into the burn chamber through the center hole of this cap. The cap can easily be removed to allow cleaning of the channels and fuel holes. Time will tell..
The flow diagram for the Fifty-Ten shows a gear oil pump with 2 gears, an oil pressure regulator that looks like 2 small pistons, a metering pump, an atomizing pressurator, and a hydraulic valve on the tube before the nozzle. I'll take pics and email you later. Not sure if it will show details well enough. The other model is the Williams R160 which is also in this book.
To get quicker cold starts, try adding a heater as close to the nozzle as possible. Injector line heater comes to mind, power resistors, cartridge heaters clamped to the nozzle/tube etc.
Thanks for that info, picture would help.
I have not completely opened up the entire pump unit yet, the rusty one I have been disassembling still has some stuck screws. I thought I could see some sort of gear pump behind the piston assembly but can't get to it yet. Pistons are pressure regulator, interesting. didn't expect a metering pump, don't know what that might be, Atomizing pressurator must be the thing I was changing the spring pressure in.
There are several things I can still try but need heat just now so it will have to wait til summer. The piston unit is what is adjustable from no-fuel to max-fuel, I have it turned up to max now and still not quite enough pressure. This assembly has 2 very tiny fuel flow holes that could be enlarged, they are designed to flow much thinner fuel oil rather than veg. The max flow with hot veg is about a 1/2 G/H but the tag indicates 1.4 G/H with fueloil. enlarging these holes should up the pressure to the point I can get a good clean burn but the piston pump body appears to be hardened steel so it may be difficult to drill out the holes, I will try it on the rusty pump first and see how it goes.
Quicker cold starting -- Can't realy do much better with additional heaters as the fuel tube is located concentrically down the inside of the syphon air tube, clamping a heater on the outside of this tube assembly might help a little but most of the heat won't get to the oil. I intend to wrap several feet of 3/8 steel tubing around the outside of the oil preheat pipe, the syphon air will be run through this tubing before it goes to the burner nozzle. This will preheat the syphon air and this hot air flowing over the center oil tube should also preheat that tube all the way to the nozzle. If I run the unit for several minutes before turning on the fuel purge solenoid the hot air should preheat the fuel tube a good bit before the hot oil passes through, might help ?, will have to do it to know how well.
For now I have simply added a small drain hole in the base of the burner stand, this will allow any unburnt oil to run out into a collection can, should not be a big problem as the burner regulator only outputs a drop of oil about every two seconds, even if it took a full minute to light this is only about 30 drops of oil, maybe a teaspoon full, the #10 collection can holds close to a gallon so it will cover a lot of cold starts.
Tim, I found out that PM's don't handle attachments. Is the email addy in your profile current? I have 8 jpg's to send you.
I sent the pics, hope it gets to you.
Here's more info from the book:
"The built in gear pump requires no aux pump for use with an outside tank. To use with a gravity fed single line system, one must remove the bypass plug shown in fig 3-8, no return line is then necessary."
There is a device called a "thrift meter":
"The thrift meter, a positive displacement pump, has a piston in a cylinder. Together they form a rotor surrounded by a steel ring and driven from the motor shaft."
Got the pictures, they will help A LOT, explains the concept and the fuel routing, will study these well, Thanks --
Thrift meter -- This is a wierd bit of design, the adjustment screw that changes the amount of oil to the nozzle tweeks this section, need to study the drawings before I will understand it.
Got the heater installed but have not yet fired it up, that will happen in a couple hours, should keep me nice and warm through tonight's forcast snow storm, I hope..
This may be stupid but if squeezing a tube with pliers did the trick... Why not use a lab tubing clamp? You can screw it up until it is just right and then leave it there. Would that not work?
mathematical elegance -- desired result achieved with minimal complication
Squeezing -- I should have explained that more thoroughly, The increased pressure was not from simply restricting the fuel hose, the "squeeze" was a slow continuous squeeze over a half second, once the tube was completely compressed and I released the pliers the flame would go completely out until the hose refilled with fuel, once fuel reached the burner nozzle it would again relight and burn with the normal yellow flame. Each time I squeezed the tube I would get a nice whitish burn.
Have not yet gotten the unit up and running in it's new location, tried last night but the unit would not output any oil to the burner nozzle, I didn't have the tools with me to work on it, should have tested it out the last time I put everything back together. It may just be clogged with gelled oil, I will pass a propane torch flame lightly over things tonight and see if that gets it going, tools going home tonight also. I know it works so just need to fiddle with it.
Are you gravity feeding the fuel? Did you try raising the height of the fuel supply to get higher pressure? This is what I use in my siphon nozzle burner to control flame length/ output. Not sure if the metering pump in the Oil-o-matic will make that non effective.
What kind of heaters do you have and how are they attached? I recall something like 1400 watts in your pm. That's a lot of power and if not regulated could boil the oil and make bubbles in the line.
I am using 5 gallon steel jerry cans as my fuel source as they can be carried inside to the heat for thawing out the gelled oil, so far one 5 gallon can lasts at least one day.
This burner is set up with both a supply and return line from the fuel tank, this creates more suction than using only a single fuel line, this has to help when sucking cold thick oil, may not be necessary but pretty much eliminates any problem with loosing prime in the pump and also keeps the oil in the tank stirred up a bit. Stirring is recomended on some of the waste oil burner websites if burning waste engine oil, it keeps all the oil at about the same thickness so the pump vollume is not dependant on the amount of oil in the supply tank. without stirring, the thicker oil will slowly drop to the bottom of the tank, as fuel is used from the tank you will be drawing the thinnest oil from the top of the tank with a floating pickup and the oil gets thicker as you use oil from the tank, as you move thicker oil the burner will receive less oil so you theoretically need to readjust the fuel/air ratios. The opposite shift in thickness occures if you draw the oil from the bottom of the tank.
This same thing applies with my veg as it contains about 30% hydrogenated vegoil and some tallow, these thicker oils always settle to the bottom.
The internal gear pump negates this a good bit but the burner was origanally set up for 2 line operation and I have not yet tested it with only one line as I had not found the location of the bypass blocking plug that has to be removed when running it with only one line. The drawings that canolafunola recently supplied me shows the location of this plug so I will eventually try operating it with only the one fuel feed line.
Heater -- The heater is made from a 8 inch long piece of pipe 2 inch pipe welded closed on one end and has a reducer welded in the other end, this will accept a short version of a standard water heater heating element, This is a 110 volt element capable of 1440 watts is fed the full 110 volts. I am powering this with a veriac voltage control to reduce the heat, I will eventually custom build a phased controled SCR type electronic temp controller that uses a temp sensor to keep the oil at a preset temp, the veriac will do for the current testing. I have found that it requires considerably warmer oil to ignite a dead cold burner unit. The testing of this burner has been done outside in about 20 deg f temps, at these temps I had to apply about 300 watts for several minutes to get the burner to ignite, once the entire unit is up to temp (burning constantly for several minutes) I could drop the heat down to about 75 watts and the burner would burn reliably and also relight just fine (instantly) as long as everything was still warm. If I turned the burner off for more than a few minutes in the 20 deg temps it would NOT relight on oil that had been continuously heated with only the 75 watts, once I turned the heat up again to 300 watts it would light up just fine after a couple minutes. with the burner inside the 20 deg temps wont be seen so I will have to play around again with the amount of heat required but it should be less than the 300 watts needed outside. I will eventually insulate the preheater so this will also help. Once the temp sensor electronics is installed the oil will stay pretty close to any preset temp nescicary. I will design the electronics so that the max 1400 watts can never be reached, by limiting the power control to no more than 1/2 of one cycle the max power that the heating element will be able to make is about 350 watts, this should be cool enough to not boil the oil and also minimize, but probably not entirly eliminate, the amount of polimerization/vulcanization on the surface of the heating element ( see low watt density heating element discussion HERE).
The commercial waste oil burners also use external fuel heaters, some use a block of aluminum with commercial cartridge heating elements inserted in holes drilled in the block, the oil, and also the syphon air, are flowed through other drilled passages in this same hot aluminum block. My local auto repair garage has a commercial waste oil heater using this technique, they use a single 400 watt cartridge heater located between the oil and air passages.
The water heater heating elements are readily available at any local home improvement store for under $7.00, the cartridge heaters have to be ordered and are much more expensive, water heater element wins.
Got the burner running finaly, I replaced the stock spring in the oil cutoff device with a bit weaker one and got oil to the nozzle, still don't have the cold startup procedure figured out yet but I finally got it burning. Once the burner was totaly warmed up it burnt just fine and I ran it for about 90 minutes on about a gallon of veg. This burner puts out a good bit of heat almost instantly, the 90 min burn took the house from being heavy-shirt chilly to being a bit too warm. There was almost no smoke from the chimney once it got up to temp, there was a small waft of grey smoke every now and then when the burner would do a flame out/restart, this happened about every 10 minutes, I think these flameouts were caused because the oil I was burning had a good amount of water in it and the water would occasionaly boil inside of the preheat chamber, this would cause a shot of steam to get output from the burner nozzle and the flame would go out and then relight as soon as fuel was again available.
It took about an hour of burning before the smoke alarm stopped ringing, it took that long for all the volitals to be driven out of the paint on the new flue pipe and also the paint on the outside ofthe burner tank, got a little smokey in the house for a while. This burner nozzle also seems to spray a fairly large diameter fog of fuel, some of this fuel contacts the inside of the burner tank and runs down inside the burn chamber, I was getting a drop of fuel from the weep hole in the burner base every 4-5 seconds. A small amount of fuel fog was also getting passed up into the flue pipe and running back down inside of it, this oil was seeping out of the seams in the flue fittings and also creating a bit of smoke. The flue pipe seams will eventually seal up with carbonized oil and this problem will go away.
One thing that has dampened my enthusiasm about this burner is that it is NOISY, there is a "whine" from the motor, also a very noticable low frequency purr from the vane type air pump, a slight "hiss" can be heard from the burner nozzle, and there is a bit of a rumble from the flame, this rumble is accentuated by the size of the burner tank.
The noise may be acceptable in the corner of a basement but it is just too loud for the corner of my living room. I will use this for heat for now but I will be rebuilding the basic burner stand assembly and another burner tank into a double bowl drip burner as soon as practical. The drip burner puts out some smoke but it is MUCH quieter and can be configured to burn without any electricity needed. The oil-o-matic needs up to 6 amps of 110 volts of electricity to run the blower and pump motor and the oil preheater.
The drip fed bowl burner burns even cool wet room temp oil just fine and no electricity is nescicary depending on how you feed the oil to the burner, I will use the same fuel feed on this burner that I am using on my other double bowl burner, it uses a very small 12 volt speed adjustable fuel pump (double bowl burner discussion is here).
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