Roger Sanders' Waste Oil Heater


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Roger Sanders' Waste Oil Heater

  1. 1. Roger Sanders Waste Oil HeaterSecond Edition After five years of use, much experimentation, many upgrades, and hundreds of letters from readers and builders, Roger Sanders has updated his original waste oil heater project with a great deal of new information and options. What follows is a revision of the original article that has far more detail and information based on practical experience.ContentsIntroduction....................................................................................2Problem 1: Cleaning.......................................................................2Problem 2: Low-heat operation....................................................8Problem 3: Oil-flow stability.........................................................9Theory of operation......................................................................13Practical points of operation.......................................................14- The flue........................................................................................14- Air tube restrictor ........................................................................15- Lighting the burner.......................................................................16- Flame-outs....................................................................................20Construction..................................................................................21Burning vegetable oil....................................................................24Automation options......................................................................26- Improved starting system.............................................................26Full automation.............................................................................26Hot water and home heating.......................................................30Wood stove conversions...............................................................32Heating a greenhouse...................................................................33Sources...........................................................................................34- Online links..................................................................................35 1
  2. 2. IntroductionI built a Mother Earth News Waste Oil Heater (MEN heater) to heat my repair and machine shop,where the heater gets used all day, every day, for about eight months of the year. The MEN heaterworks as claimed and puts out a lot of heat. I was pleased to find that I could successfully use wasteoil to heat my shop.However, after using the MEN heater for several months, I became sofrustrated with its problems that I concluded that it is unsuitable forserious, regular use. So I embarked on a journey to design and build amore practical heater.There are three big problems with the MEN heater. These are:1) Cleaning2) Low-heat operation3) Oil-flow stabilityProblem 1: CleaningCleaning the MEN heater is a major hassle. Burning waste motor oilleaves deposits in the combustion chamber. Calling these deposits"ash" is deceiving as they can be as hard as concrete and just as hardto remove.Experience reveals that there are actually several different types of Photo #1deposits. These can be broken down into two basic types that Ill call MEN heater built by"ash" and "coal." Journey to Forever"Coal" deposits are dark gray (almost black) and appear much like unburned charcoal. Thesedeposits are very hard and must be chipped away from the burner surfaces using a hammer or coldchisel and hammer. They form on the hot metal surfaces inside the combustion chamber where theoil changes state from a liquid to a gas (vaporization)."Ash" deposits are crusty, light, airy, and are easy to wipe away with a gloved hand or putty knife.They mostly are light in color, ranging from tan to light gray, althoughsome are black. For easy cleaning, "coal" must be avoided at all costs,only "ash" must remain to be removed.Vaporization heaters (like the MEN heater) must be cleaned every fewhours of operation, depending on the oil used, the contaminantspresent, and how hard you run the heater. If you use your heater everyday, all day, this means that youll have to clean your heater everymorning before you light it for the day.This cleaning ritual is a serious problem with the MEN heater due toits complicated burn chamber. There are many parts and some of themhave rounded surfaces, which make them hard to access for cleaning,and they are bolted together. The heater produces heavy "coal" Photo #2deposits. MEN heater burn chamber 2
  3. 3. The nuts and bolts inside the MEN heaters combustion chamber become encrusted with coal,making them difficult to unscrew. Once the parts are separated, it is necessary to use a hammer andchisel to break away the coal.Its rounded surfaces are hard to clean because a hammer, putty knife, or chisel only contacts a smallarea, which forces you to spend a lot of time cleaning small spots, and the parts must be constantlyturned to expose new areas to clean. It is much easier and faster to clean flat surfaces. It is necessaryto use a drill to clear out the holes in the burner. This dirty, messy, time-consuming and frustratingtask gets old very quickly.Others have tried to deal with this problem, like Bruce Woodford. I tried Bruces forced-air heater,which uses a simple combustion chamber filled with loose bolts to make it easier to clean.This is a simpler design than the original MEN heater, and it is more efficient. It was easier to cleantoo. I give Bruce high marks for his design. But there were still problems.Shaking the bolts as recommended did a fine job of removing the ash,but the bolts were also coated with coal, and shaking them did notcompletely clean them. Eventually you have to beat on them with ahammer to break the really hard deposits free, and this was time-consuming and difficult as they are hard to hold and have roundedsurfaces.An easier solution is to replace the bolts, but large bolts areexpensive. The cylindrical burner also became coated with coal, andbecause access to the inside is very limited, cleaning it was difficult. Photo #3 Bruce Woodfords combustion chamberAnother issue was that fishing the loose bolts out of a pile of ash wasa messy business. Setting the bolts back into place in the combustion chamber was a fiddly job thattried my patience. I didnt like the noise and complexity of using an electric blower. The heaterwould not run reliably at low heat settings.All this frustration finally compelled me to design my own combustion chamber and heater.Conceptually, vaporization heaters are simple and easy to design. They work by vaporizing liquidoil upon a hot metal surface. The vapors are flammable, and when mixed with adequate amounts ofair, they burn very well. But making a design that doesnt produce coal is very challenging.The heart of the problem is that as oil boils and evaporates from the hot vaporization surface, itleaves behind all the "sludge" from the oil that will not vaporize and burn away. This sludge isturned into a hard mass by the heat of the burning oil. I found that pure, clean, new, oil has fewdeposits, but used crankcase oil is full of contaminants, detergents, and various additives, whichremain behind.This problem is much like boiling water in a pan or teapot. As the water changes to steam, theminerals in the water are left behind as "scale" in the pot, forming hard deposits that are difficult toremove.Commercial waste oil heaters partly solve this problem by atomizing the oil through a nozzle ratherthan vaporizing it. The contaminants are atomized as well, so they are not left behind in the nozzle.A blower is usually used, causing the contaminants to be blown out the flue into the atmosphere. 3
  4. 4. The contaminants include toxic substances such as heavy metals (including lead, zinc, cadmium andchromium*) that are better left behind in a burner rather than being discharged into the atmospherewhere we can breathe them. So a vaporization heater is likely to be more "green" than anatomization heater. My heater is environmentally sound because it distills the oil, automaticallyremoving heavy metals from the oil before burning it. This heater effectively eliminates airborne,heavy metal pollution.Atomizing heaters have other, major problems. They require compressed air or an hydraulic pumpto atomize the oil, the oil must be pre-heated, very well filtered, the nozzles tend to clog withcarbon, low-heat operation is not practical, and the pumps, nozzles, and air compressors add a lot ofcomplexity and maintenance issues. Also, they use large amounts of electricity, which is expensiveand defeats the idea of using "free" fuel and being environmentally responsible.I like the simplicity, silence, and economy of a vaporization-type waste oil heater, so I focused myattention on making one that is extremely simple, noiseless, requires no electricity, that producesmostly soft ash rather than hard coal, and has only flat surfaces that are easy to clean.I have designed, built, and tested dozens of burners in trying to develop an ideal combustionchamber. There isnt the space in this article to describe all the details, changes, and experimentationinvolved. So Ill just summarize my findings and describe the burner that solves the problems.After considerable experimentation, I eventually settled on the idea that the simplest combustionchamber was best. This took the form of an open "pot" into which the oil would drip, vaporize, andburn.I tried various types and sizes of pots, with and without different types of internal assemblies. Ifound they all could be made to work.Of course, some worked better than others. I found an 8-inch cast iron pot (20.3 cm) worked quitewell. The nice thing about an open pot is that it is only a single part, does not require anydisassembly, and can simply be lifted out of the stove for cleaning.But no matter how I made my burn pots, they all produced large amounts of coal deposits that werehard to clean. But at least they presented a relatively simple surface to clean and there was nodisassembly required, even though they required a hammer and chisel to clean them well. I was notsatisfied, so I continued to search for a better burner.After more head-scratching and study, I came up with the idea of using a LIQUID vaporizationsurface instead of a solid, metal one. I reasoned that vaporizing the oil off a liquid surface wouldleave the contaminants behind in the liquid or they would blow off the liquid where they would besoft and easy to remove. In either case, there would be no hot, solid, metal surface where coal couldform. This insight turned out to be one of the two keys to easy cleaning.My second insight had to do with the material out of which the burner was made. Usually burnersare made out of cast iron or steel as these will handle a great deal of heat before they melt. But Ifound that they are much harder to clean than an aluminum surface. Why would this be?* See Waste Motor Oil Management May Pose Threat to Health and the Environment, ScienceDaily, Jan. 15, 2004; Pollution Prevention Impact of Used Oil, Iowa Waste Reduction Center, 2008, quoting the US Environmental Protection Agency 4
  5. 5. After trying to clean a hot aluminum burner one day, compared to cleaning a cold one, I came tounderstand that because aluminum expands and contracts a great deal with temperature, coaldeposits cant stick to it.If coal is formed on an aluminum burner when it is hot, the coal will break free from the burner asthe burner cools and contracts. Since the coal is very rigid, it just cant stick to an aluminum surfacethat is moving and shrinking under it.But how could I make a liquid vaporization surface? Initially I made a shallow metal cup 4 inchesin diameter (10 cm) and 3/4 of an inch deep (2 cm) into which the dripping oil would pool. The cupwas in the form of a shallow cylinder with a flat bottom. I made it by welding a 1/4-inch thick (6.35mm) steel plate to a 3/4-inch long section of 4-inch steel pipe. I placed this inside the 8-inchdiameter (20.3 cm) cast iron pot that I had been using as my burner.I figured that the oil pool in the cup would release vapors into the pot where they would burn. Sinceno liquid oil would enter the pot, there would be no coal formed in the pot. But I found that thingsworked a bit differently than expected.The oil dripped into the cup where it boiled and oil vaporizedas expected. But as air flowed over the surface of the oil, itmixed with the oil vapors, and burst into flame directly overthe top of the oil pool. Photo #4 shows the flames over the oilpool as seen through the heaters air tube. No oil vapor enteredthe pot, no burning occurred within the pot, so the pot was noteven needed. This simplified the design even more.Initial tests of this cup were promising, as the deposits weremostly ash and very easy to remove. However, some coal Photo #4formed on the top edge of the rim of the cup that extendedabove the oil pool. Ideally I needed to modify the cup to eliminate this trouble spot.But there was a much bigger problem, which involved the rate of oil flow. If only a small amount ofoil was dripping into the cup, it vaporized completely and eliminated the oil pool, which resulted inthose dreaded coal deposits. If I ran too much oil into the cup, it overflowed, the oil spilled out intothe pot, and the pot got coated with coal.In short, it was difficult to find an oil flow that kept the oilin a liquid pool which didnt overflow the cup. In any case,there was only one heat level possible and I had no way tocontrol the heat output.After more head-scratching, I figured out that what Ineeded was a cup whose area increased as the oil flowincreased. The increased oil pool area would make itpossible to vaporize more oil without it overflowing the Photo #5cup.I developed a cup that did exactly that. I built a shallow, 5-3/4-inch diameter cup (14.6 cm) whoseinterior surface was in the shape of a shallow, inverted cone or funnel of 12 degrees. This alsoallowed me to eliminate any lip that could accumulate coal. Photo #5 shows this conical burner. 5
  6. 6. This conical burner design allowed excellent heat control. When only a little oil was beingintroduced into this new burner, it would form a pool about an inch in diameter (2.5 cm) in themiddle of the cone that burned very hot. When a lot of oil was fed into the burner, the oil poolexpanded out to 4 or 5 inches in diameter (10-13 cm), producing much more heat output.As the burner got hotter from the increased oil flow, the oil would vaporize faster and the pool of oilshrank down in size to about what it was on low heat. The size of the oil pool was self-regulatingand ensured that there was always a pool of oil present that never overflowed the burner as long asthe oil flow was kept reasonable.This design allowed me to obtain excellent heat control over a very wide temperature range. I couldget huge amounts of heat or turn it down to where the heater was just barely warm. Since theburning occurs over the top of the oil pool, the pool is always extremely hot and burns well even atvery low oil flows. It is like using a large combustion chamber for high heat and a small one for lowheat. As a result, the heater burns efficiently and uses a minimum of fuel for any given heat setting.Because the oil pool does not normally expand to encompass the entire burner, some coal isproduced on the edges of the burner. However, because the burner is aluminum, the coal does notstick and is easily removed.I tried several different sized burners. I found that I had to use a large enough burner to handle anincrease in oil flow while allowing the burner to get hot enough to shrink the oil pool back down toits usual 2-inch size (5 cm). If I used a burner only 2 inches indiameter, it would overflow anytime I increased the oil flow. If Iused one larger than 6 inches (15.2 cm), the extra area was neverneeded. So I settled on a burner that is 5 inches in diameter(12.7 cm).I experimented with different tapers on the burners cone. Thiswas not critical. But the taper had to be steep enough to holdenough starting fluid and to prevent overflowing when the oilflow was increased. I found a 10 to 15-degree angle wassatisfactory. I settled on a 15-degree angle because it held more Photo #6starting fluid.This burner is incredibly simple and is quick and easy to clean. Cleaning takes only seconds as allyou need do is lift the burner out of the heater and scrape its flat conical surface with a putty knife.Photo #6 shows the burner after it has been run all day. Photo #7shows the burner after passing a putty knife over one side. Theash just falls away without any effort.Soot is formed in the flue and inside surfaces of all oil heaters.This soot is self-cleaning on the inside of the heater (but not theflue pipe), as it gradually flakes off the inside surfaces of theheater and the flakes fall to the bottom of the heater where youcan easily remove them. Photo #7You dont have to clean them out often as you can wait until they get several inches deep. With theMEN heater, you not only have these soot flakes to remove, but you quickly accumulate a lot of ashfrom the paper used in the lighting process. 6
  7. 7. My heater does not use any paper, so has no paper ash. Considerable ash is blown off the conicalburner rather than sticking to it, which is nice because this ash falls to the bottom of the heaterwhere it mixes with the flakes of soot that fall from the inside of the heater. Photo #8 shows sootand ash in the bottom of the heater.I run my heater continuously, so about once a month Iremove the debris. The ash does not adhere to the heaterssurfaces and weighs nothing (much like wood ash), so it isvery easy to remove.I use a small, hand-held, garden shovel to scoop up theashes and put them into a metal bucket. I eventually transferthem to a normal trash can after I am absolutely sure theyare cold (you dont want a fire in your trash). A vacuumcleaner works very well, but cleaning a vacuum full of soot Photo #8and ash is messy, so I prefer using the shovel.All oil heaters produce some smoke, odor, and a lot of soot. This one is no exception. This isbecause oil is a hydrocarbon fuel. It contains long chains of carbon atoms surrounded by hydrogenatoms. The heater oxidizes the hydrogen, forming water vapor, which is the main exhaust productfrom the heater.The carbon in the oil is not burned. It remains as solid carbon molecules we know as soot. The sootmolecules flow out of the flue with the exhaust gases and you see this as smoke. Generally thesmoke is a bit less than what you would see from a wood stove, but it certainly will be visible.Photo #9 shows the flue pipe with myheater running on medium heat, with the oilflow at about 6 drops per second and asurface temperature of 500 degrees (260degrees C). Smoke is visible, but you haveto look carefully to see it. The stove willsmoke more when cold than when hot, justlike a wood stove.Like a wood stove, the exhaust from an oilheater has a characteristic odor. In myopinion, the odor is not offensive. But youwould not want to smell it continuously(again, just like a wood stove). Normally,you dont smell any odor. But if the wind is Photo #9just right, it can pull the smoke down toground level where you can smell it. You can usually prevent this by making sure that the top of theflue is well above the peak of the roof.Note that soot may seem a dirty pollutant, but this is not necessarily so. Soot molecules are actuallycarbon molecules. As such they simply drop out of the air as harmless carbon. If you actuallymanage to burn (oxidize) them, you convert them to a gas – either carbon monoxide, a deadlypoison, or carbon dioxide, the well-known greenhouse gas that is now considered an environmentalpollutant. So soot is probably a more benign way to deal with the carbon in oil than burning it. 7
  8. 8. Even though the soot is only carbon, one should avoid breathing it. It is well proven that breathingtiny soot particles can cause asthma and lung disease. However, my heater does not produce the tinysoot particles one finds in diesel engine exhaust fumes. The soot particles from my heater are huge,so our respiratory system should easily be able to capture and remove them before they reach ourlungs. So even breathing the soot from my heater will probably not cause disease.In short, I consider my heater to be environmentally friendly and essentially pollution-free.However, your neighbors may not think so as they see smoke coming from your flue. This could bea problem in certain locations.Like a wood stove, you can expect an oil stove to be messy. That is the price you will have to pay toget free heat from waste oil.The soot will gradually clog up the flue and you will need to clean it. But the soot is soft and veryeasily removed, unlike the creosote formed in a wood stove flue. Also, the soot is non-flammable,so you have no risk of a flue fire, which is a major concern with a wood stove.To make cleaning the burner easy, do not put any sand or gravel in the bottom of the heater as isrecommended for the MEN heater. Just leave the bottom of the heater bare steel so you can use theshovel without picking up any sand.Problem 2: Low-heat operationUsing an oil pool as a vaporization surface solves the second major problem of the MEN heater, andthat is low-heat operation. The MEN heater produces a lot of heat and requires a rather brisk oilflow where the oil falls in a steady stream rather than in drops. It has a large vaporization surfacethat must be kept hot for efficient operation. This makes it impossible to run the heater at a low heatsetting, which often is needed in mild weather conditions.By comparison, the flame in a conical oil burner will withdraw to operation only within the centerof the burner where the heat remains intense. This allows the heater to be run on a very low heatsetting as only a slow oil drip (just a couple of drops per second) will still result in excellent flamestability and efficiency. In other words, the fire stays hot and efficient, but its size is smaller.When turned down to a low setting, the oil flow can be reduced to only about 2 drops per second,which is about a teaspoon per minute, or about 5 ml per minute. Such a low flow will burn less thana gallon of oil per day (3.8 liters). When the heater is running on "high", it can burn about onegallon per hour, which is about 2 ounces per minute or about 60 ml per minute.An additional bonus is that lighting this heater is much easier than the MEN heater. You do not needpaper, wood chips, or perlite. You do not need a two-stage lighting process where you light thepaper first to start the draft then light the burner.All you need to do is fill the burner with kerosene (about 1-1/2 ounces, 44 ml) and light it. Close thedoor, turn on the oil to a low setting, and walk away. The heater will establish a draft automaticallyas soon as you close the door and the flame will be self-sustaining immediately. After about 20minutes, you can come back and turn the oil up to a higher setting if you wish. 8
  9. 9. Photo #10 shows the burner just after being lit. Notethat the flames are going up at this point. But whenyou close the door, the draft will start and fresh air willbe drawn down the air tube that is directly over theburner. This air will force the flames to movehorizontally and extend radially out from the center ofthe burner, forming a "flower of flame" that will getthe walls of the heater extremely hot.Some minor issues have to be addressed when using aconical oil burner. One is excessive air flow velocity. Ifthe air comes in too fast, it will blow the vapors off thepool of oil and the heater can "flame out." Photo #10You need sufficient air to burn the oil completely, but you have to keep the air velocity low. Afterconsiderable experimentation, I found that you must use a large air tube (a minimum of 4 inches indiameter, 10 cm), but you must use a restrictor at its inlet to keep the velocity low.The restrictor I use is just a thin metal plate with a 1-1/2 inch(3.8 cm) hole in it that sits at the entrance to the air tube. Photo#11 shows this plate.This looks professional, but is hard for DIYers to make. Anoption that works just as well is a 2 x 4 inch (5 x 10 cm),rectangular piece of metal that you lay across the intake tube sothat all but an inch (2.5 cm) of the opening is obstructed. Photo Photo #11#12 shows such a plate.Note that I do not use an air pipe pre-heater like the MEN stove.It just isnt needed. My air pipe starts at the top of the heater andends 6 inches (15.2 cm) above the burner. It gets very hot fromthe fire inside the heater, and since the air flows through thepipe slowly, the air has adequate time to get hot.Problem 3: Oil-flow stability Photo #12Oil-flow stability is a problem with all gravity-fed, waste oilheaters. This is because the viscosity of the oil changes dramatically with temperature. The MENheater is extremely troublesome in this regard because it runs the oil feed line around the hot fluepipe. This is a mistake.Why? Because having the oil line in contact with the flue heats the oil in the line as the stove getshot. This reduces the oils viscosity, causing it to flow faster through the oil control valve. Theincreased oil flow causes the stove to get hotter, which causes the flue to get hotter, which causesthe oil in the pipe to get hotter, which reduces its viscosity further, which causes it to flow faster,which causes the stove to get hotter, which reduces the oils viscosity more, which causes it to flowfaster, etc.What you get is a positive feedback loop, which causes the heater to get too hot and the oil flow tobecome excessive. So after a few minutes, you have to turn down the oil flow, which reduces the 9
  10. 10. heat in the flue, which increases the oils viscosity, which reduces the oil flow, which reduces theheat, etc., until the fire goes out – unless you turn the oil flow back up again, which causes moreheat, more oil flow, etc. In short, the heaters operation is inherently unstable and unreliable. Thisproblem requires you to constantly monitor the oil flow and adjust it every few minutes.Oil-flow stability is essential and it is impossible to attain as long as you have this positive feedbackloop problem. To reduce the problem, keep the oil feed line as far away from the flue as is practicalso that the temperature of the feed line remains relatively constant.As the room heats up, the oil in the line will still become slightly less viscous and the flow willincrease slightly, which may require you to adjust it. But once you get the room at the temperatureyou want, the oil flow can be set to maintain that temperature and it will be stable for a long periodof time – usually all day, unless the outside temperature changes significantly, which affects theflow of oil from the outside tank.The above change helps a lot, but doesnt completely solve the problem. Two additional things arenecessary to achieve truly stable oil flow.First, it really helps to use a relatively high oil pressure. I eventually put my oil tank on a hill abovemy shop, which gives me a 30-foot (9-meter) head of pressure. The increase in oil pressurecompared to having a tank just a couple of feet above my heater significantly helped stabilize oilflow. While this added pressure makes adjusting the oil control valve more sensitive, the oil-flowstability is very much improved.I understand that many readers dont have a hill next to their shop upon which they can put their oiltank. If so, just make every reasonable effort to place the tank as high as possible. Alternativesinclude using compressed air to pressurize the tank – 10 to 15 psi isplenty (0.69-1.03 bar) – or by using a small oil pump, although thisstarts to make things complicated and requires electricity tooperate.The other major problem associated with oil-flow stability is thatthe typical "needle" valve found at hardware stores is not designedto precisely control the flow of liquids. These valves are reallydesigned just to be small on/off valves. I found that these valvesgave me only one-eighth of a turn between minimum andmaximum heat on my heater. They need to be much more gradualin their operation.If you carefully inspect one of these valves, the reason for theirpoor performance will be obvious. They are very crude and donteven have a tapered needle as is necessary to precisely controlflow. They are built using the flat end of the shaft to cover oruncover an orifice. And the orifice is about 3/16-inch in diameter(5 mm), which is much too large for our use. As a result, just a tiny Photo #13amount of shaft rotation results in a relatively large increase in oilflow. This is unacceptable.At the top of Photo #13, you can see the valve assembly. Below that Ive placed the control shaft,showing that it has a flat end. Below that, Ive placed a proper "needle" valve shaft. 10
  11. 11. As if the lack of a needle valve isnt enough of a problem, the threads on the flat-end shaft are looseand sloppy, which means that the valve will not necessarily be in the same position with regard tothe shafts rotational position. As a result, you cant get reproducible flow settings based on theposition of the control shaft. This problem could be improved if a strong spring were used to holdtension on the threads, but these valves have no such spring.If you use one of these valves, you can improve the reproducibility of the settings by alwaysadjusting the valve in one direction only and pushing in (or pulling out) on the shaft the same wayevery time you rotate it so you maintain a stable position between the threads. The valve settingswill still not be completely reliable and reproducible, but you will get some improvement.The only real solution to this problem is to use a valve with a tapered needle and precision threads.It is also very desirable to have a sight glass in the valve so that you can see the oil drops falling. Bywatching the drip rate and checking a wood stove thermometer that you place on the side of theheater, you can easily get excellent control of the heat output. Such valves are commerciallyavailable.The oil drip valve should be placed close to the heater for precise oil control. I put mine right at theentrance of the air tube. This area stays cool because air is flowing into the air tube.The 1/4-inch (6.35 mm) copper oil feed line must run inside the air tube. This is because the oil linemust be kept cool enough that the oil in it doesnt boil. If it boils, vapors will spray out of the tubeand catch fire. While this wont hurt anything, ash will soon form around the end of the oil line andclog it. The oil feed line should end about 2 inches (5 cm) from the end of the air tube so that it isnot exposed to the direct flame.The oil feed line is cooled by the fresh air flowing through the air tube. Also the air tube blocks theintense infrared radiation coming from the fire. So the oil in the tube remains liquid.I installed a mica window in the door of my stove. This is a nice feature as you can see the flame,but it gets covered in soot. I have tried many ways to prevent the soot from getting on the window,but have not been completely successful. So a window isnt very practical.It is better to just observe the flame by looking down through the air pipe. This is a bit awkward. Tomake it easy, attach a small mirror at a 45-degree angle above the air tube. You can then look at themirror horizontally instead of straining to look down the tube vertically.You will need a good filter to prevent your oil control valve from getting clogged up. Filtering theoil through panty-hose is not good enough.Waste oil always has water and/or antifreeze in it. Even if nobody put antifreeze in it, it will alwayshave water mixed with it as water is one of the products of engine combustion. The water will bemixed into the oil as an emulsion, so it will not all just settle to the bottom of the tank where it canbe drained away just one time. The filter screen causes the water to separate from the emulsion, soyou will have to drain water frequently, usually daily as part of your start-up ritual.Unlike water, antifreeze quickly settles on the bottom of the tank. If there is antifreeze involvedwhen you get a new tank of oil, you may have to drain water several times over a few hours untilmost of the antifreeze is gone. Then draining water daily is sufficient. In any case, you will bedraining water frequently, so you need to make it fast and easy. 11
  12. 12. A good filter will have provisions for removing water. If you put aquarter-turn ball valve in the bottom of my oil filter/water-separator,draining the water only takes a few seconds. I installed a clear hose atthe outlet so I can see when the draining water turns to oil. Photo #14shows this filter assembly.Experience is the toughest teacher – she gives the test first, then thelesson. So another issue I learned the hard way is that your oil feedline must drain downhill at all times until it reaches the water/oilseparator. If there is any low spot in the line, it will accumulate water,freeze, and prevent stable oil flow.I originally put my oil line on the ground and then ran it up the side ofmy shop where it made a very neat installation. But this formed a lowspot at the bottom of the wall, and this ruined my oil flow. I had toelevate the line to get stable operation.Photo #15 shows this suspended line. It isnt as neat as running the line Photo #14on the ground, but it works perfectly.It is interesting that nobody seems to mention the issue ofcollecting oil. This is a major problem as you will burnquite a lot of it over time. I burn 50-100 gallons per month(190-380 liters) during sub-freezing weather to heat my1,200 square foot shop (111 square meters) that has onlymoderate insulation. So you must have a fast and effectiveway to collect and store oil.Collecting oil is a messy hassle, so you dont want to haveto do so any more frequently than necessary. In short, you Photo #15want a big oil tank.There is no cheap and easy solution to this problem. Iconsidered 55-gallon oil drums (200 liters), but when full,these are heavy, hard to handle, and a nuisance to connect afeed line to without spilling oil and making an environmentalmess. I quickly realized that I needed a serious oil transportand storage system.While my heater cost me nothing to build from scrap parts, Ihad to spend about $500 to build a tanker/trailer and pumpsystem for my car. This consists of a small, inexpensive ($200)trailer kit (from Northern Tool or Harbor Freight Tools) to Photo #16which I mounted a 225-gallon (850-liter) plastic tank ($220).Photo #16 shows this tanker/trailer.When this tank is full of oil, the gross weight of the tanker/trailer is about 1,400 pounds (635 kg),which is the maximum weight I care to pull with my car and it is the maximum weight allowed bymost small trailers. So dont get a tank that is too big unless you have a big, powerful tow vehicleand a larger trailer that will handle the weight. 12
  13. 13. You also need some sort of hydraulic pump to transfer the oil to your tanker/trailer. Whilecommercial waste oil pumps are available, they cost hundreds of dollars and they dont pump oil asfast as I would like. So I connected a used hydraulic pump to a 2-horsepower (1.49 kW) lawnmower engine. This, with suitable plumbing, makes it easy to pump the oil.Oil is thick and viscous, particularly in the winter when you will need to get it. It is hard to pump itfast. My pump is powerful, but it still takes about 30 minutes to fill my tanker/trailer when thetemperature is below freezing. Thats longer than I like to wait, but since I only need to collect oiltwo or three times per year, it is acceptable.When I get home with the tanker/trailer, I connect it directly to my heaters oil feed line and use thetanker/trailer as my heaters oil tank. I use a 3/4-inch (1.9 cm) ABS plastic feed-line that is about130 feet long (40 meters) to feed oil from my trailer (on the hill behind my shop) to my oilfilter/water-separator inside my shop. I only switch to a 1/4-inch (6.35 mm) copper line about 4 feet(1.2 meters) above the heater.Eventually I installed a larger, 1,600-gallon (6,500-liter) stationary tank. This makes it possible tocollect oil only in the summer when it pumps faster and being outside is more pleasant. I drain mytanker/trailer into the big tank as often as I wish. I no longer have to worry about running out of oilduring the winter. In fact, with the big tank full, I have enough oil to last for at least three winters.Theory of operationThis heater is extremely simple. But many readers are confused as to exactly how it operates. Thisgenerates a lot of questions in my e-mail. So let me explain exactly how the heater works and howto operate it.This discussion will be very detailed so that every common question is answered. Please read thissection (and the next on practical points of operation) carefully, because if you have questions,youll probably find the answers here.The heart of the heater is the flue. Yes, the flue. That is because the flue is the "engine" that powersthe flow of gases through the heater.Hot exhaust gases in the flue are lighter than the air around them, so they rise. As they do, theydraw a small vacuum inside the heater shell. This vacuum "sucks" air down the open air tube. Thisdownward flow of air is directed at the center of the burner.Note that the vacuum caused by the flue makes it possible to have air leaks around your door withno problem. Any leaks in the heaters shell will result in a little air being sucked through them intothe heater rather than having any smoke or fumes come out into your room. So it is not necessary tohave a perfectly airtight door.Liquid oil will not burn. It must be vaporized to a gas. The burner is hot enough to boil the oil thatis in it and the oil changes state from a liquid to a gas, just like boiling water changes to steam. Thisis called vaporization. As the oil vapors flow off the oil pool, they mix with the fresh air from theair tube and start to burn.The air coming down the air tube forces the flames to flow horizontally off the burner. They do notflow vertically upward into the air tube. 13
  14. 14. The horizontal flames form a ring of fire around the burner – what I call a "flower of flames." Theseflames lick the sides of the heater shell and quickly and efficiently transfer their heat to the heatershell.The hot heater shell transfers its heat out into your room. It does so by producing a lot of infraredradiation that you can feel from several feet away, and by heating the air next to it (convection).The larger the surface area of the heater shell, the more heat will be transferred to your room. Sousing a large heater works better than using a small one.The heat transfer to the heaters shell is quite good in this heater design, so very little heat is wastedgoing up the flue. The flue gases are relatively cool. The flue doesnt get very hot. In short, theheater is quite efficient.Practical points of operationThe flueThere are several practical issues that you need to keep in mind when operating the heater. The firstis to take care of the heaters "engine." This means that the flue must be tall enough to work welland produce a strong draught.Your flue must be a minimum of 9 feet tall (2.7 meters) – and taller is even better. Ideally, it shouldbe dead vertical with no bends or horizontal sections. Dont expect the heater to work with a "stub"flue that is only 3 feet tall.If you simply cant install a completely vertical flue (such as if you must run the flue through awall), there are several things you can do to minimize problems. The first is to use 45-degreeelbows in the flue instead of 90-degree ones. By doing so, you will avoid having any horizontalsections of flue and the exhaust can rise upwards throughout the entire flue.Horizontal sections of flue simply should not be used. You can make it work with 45-degreesections of flue instead. And any section of flue that is at 45 degrees should be duplicated by asimilar amount of vertical flue.In other words, if you have a 10-foot (3-meter) run of flue, but 3 feet of that is at 45 degrees, youshould add an additional 3 feet of vertical flue to compensate. So the total length of the flue will beincreased to 13 feet (4 meters).Soot will accumulate in the flue. It will eventually clog the flue and the heater will misbehave(which I will discuss shortly). So the diameter of your flue must be a minimum of 6 inches (16 cm).Larger is better, but a 6-inch flue is about as large as you can fit into most water heaters that will beused for this project. A 4-inch flue will work if perfectly clean, but soot will quickly clog it. So useat least a 6-inch-diameter flue.The amount of soot that accumulates in the flue will vary depending on the oil you are burning. Igenerally find that I need to clean the flue every 300 to 500 hours of operation for motor oil. Whenin doubt, clean more often. 14
  15. 15. Note that most flues are designed for wood stoves. This means that the cap on the top of the fluepipe will have a screen in it that is intended to catch sparks and glowing embers to prevent wildfires.These screens quickly become clogged with soot. So remove them. Oil stoves dont make sparksand embers, so there is no risk of them causing a wild fire.The soot is not flammable like creosote deposits that accumulate in a wood stove flue. So there isno risk of a flue fire in an oil stove.The soot is soft and easily removed. You do not need to use a stiff brush like you would to removecreosote in a wood stove. Certainly a flue brush will work very well to clean the soot, but it surewill be messy. Using a brush requires you to get up on the roof, which in winter with snow and/orice on the roof is risky.To make cleaning the soot fast, easy, and relatively clean, I blast compressed air up my flue. Thisblows the soot out onto the roof where the wind blows it away or the rain washes it off. This is a lotbetter than brushing buckets of soot into the heater and then having to shovel it out.To use compressed air, I put a 1-inch (2.5 cm) hole in the heater shell right at the base of my flue. Ican stick a blow gun in there and blast the soot up the flue. I plug the hole with a pipe plug or smallmetal plate when Im done.In my experience, compressed air will only blow through about 8 feet of soot (2.4 meters). Sincemy flue is 12 feet tall (3.7 meters), I have an additional 1-inch hole about halfway up the flue. Toclean the flue, I blow out the upper section of flue first, then blow out the bottom section, whosesoot can then pass freely through the upper section. I have a small metal plate that I screw over theupper hole when I am done cleaning it.Air tube restrictorThe air tube restrictor is extremely important. It is absolutely essential that the air flow be severelyrestricted for the heater to operate properly! Many readers incorrectly believe that they need a largeamount of air flow to make the heater burn "cleanly" and "efficiently." Just the opposite is true.Why? Because if excessive air flows into the heater, it will blow the flames off the burner. If theflames are only burning around the outer edge of the burner, the heater will produce very little heat(poor efficiency), the heater will be very unstable, and most likely you will have a spontaneousflame-out.I cannot stress this enough – the flames must be over the burner at all times. Too much air will blowthe flames off the burner. You must severely restrict the air flow for efficient operation.Excess air will not blow the flames off the burner if the burner is really hot. So it is possible to openthe restrictor more once the heater is really cooking. But doing so will not improve combustion.Once the oxygen needs of the burner are met, the only thing excess air will do is cool off the heatershell and drive the hot gases out the flue before they have had time to transfer as much heat aspossible to the heater shell. 15
  16. 16. So avoid the urge to use more air to get a "cleaner" burn. It doesnt work that way. Trust me – usethe most restriction possible for best heater performance.So how do you know how much restriction to use? You can tell by watching the flame on theburner. A "normal" flame that has adequate air for complete combustion will be highly energeticand be mostly yellow in color with streaks of white in it. An oxygen-starved flame will be sluggish,orange in color, and very smoky.The amount of air required will be about the amount that will flow through an area of about 1-1/2square inches (9.7 sq cm). This will be a hole about 1.3 inches (3.3 cm) in diameter. If you are usinga restrictor with a straight side, you will want to close off about 80% of the air tube, which will beall but about an inch (2.5 cm) of the air tube opening.Many readers are concerned about wasting a lot of warm room air feeding the air tube and the fire.But you can see that if you use an appropriate amount of restriction, the amount of air sucked intothe heater will be very small. So it isnt a problem.However, if you want to plumb in outside air, feel free to do so. The only disadvantage will be thatyou cant look down the air tube to see the flames and monitor the heater.Lighting the burnerFill the burner with kerosene. It needs to be completely full. So be sure the burner is level. Ifnecessary, shim your heater or the burner pedestal so the burner is level.A turkey baster works well for filling the burner. They are cheap and readily available from foodstores. The bulbs on these are usually latex, which kerosene will gradually dissolve. But if you storethe baster with its point down, kerosene will run out of the bulb and it will last a long time.Light the pool with a lighter or propane torch then close the door.You would think that the flame and smoke would go straight up the air tube at this point. But itusually wont if the door is closed.The reason for this is that the air tube is restricted, while the rest of the heater is wide open spacewith a big flue opening at the top. The flames find it easier to go out into the heater space and up theflue.As soon as they do (it may take a few seconds), air will start to be sucked down the air tube. Youcan feel the cool flow of air near the inlet of the tube with your hand.If your heater blows smoke out the air tube, then it is almost certainly because you have a flue thatis clogged with soot. Cleaning the flue should fix it.If your heater has a clean flue and still blows smoke out the air tube (very unlikely), you can alwaysclose the air tube completely with the restrictor plate or with your hand. After 10 or 15 seconds,enough hot gases will have been generated inside the heater that you can slowly open the air tubeand air will be drawn into it normally. 16
  17. 17. Note that smoke will go up the air tube if you have the door open. This is because the flue vacuumwill draw air in more easily through the relatively large door than through the restricted air tube. Sowhen the door is open, no air will come down the air tube and the flames can and will go up it.You will need to start the oil flow at some point after the burner has been lit. You can do thisimmediately or wait for a minute for some of the kerosene to burn away. Either way works. But youmust avoid flooding a cold burner with raw oil or the flame will go out and oil will flow over theburner into the bottom of the heater.So start with a "low" oil flow. This means an oil drip rate of 2-3 d/s (drops per second) as seen inthe sight glass in the valve.Usually the kerosene will get the burner hot enough that there will be sufficient heat for the burnerto vaporize 2-4 d/s of 5W-30 motor oil from a cold start. Until you become familiar with yourheaters behavior, you should wait and observe it for at least 10 minutes after you light it to be surethat it doesnt flame out.Sometimes a single shot of kerosene wont get the burner hot enough to sustain oil combustion. Thisis unlikely with 5W-30 motor oil, but if you use heavier petroleum oil or veggie oil, the burner willneed to be hotter. If the flame keeps going out, you need more heat.You can get more heat by using a second shot of kerosene. However, you must be careful to avoid aflash fire when adding more kerosene. Fortunately, it is easy to avoid. Heres how:Understand that if you put kerosene into a hot burner that has no flame, the kerosene will vaporizeinto a fog inside the heater shell. If you then attempt to light it, the kerosene vapors will suddenlyignite, causing a big blast of flame to come shooting out the door of your heater.This small explosion probably wont harm you, but it will most certainly get your attention. Youllprobably be missing some eyebrows and other body hair that gets burned off by the flash fire.To avoid this, NEVER PUT KEROSENE INTO A FLAMELESS HOT BURNER!But it is perfectly safe to put kerosene into a burner that has flame on it. The flame will ensure thatthe kerosene vapors are burned as fast as they form. This will prevent an accumulation of kerosenevapor that can explode.So to get your burner really hot, light a load of kerosene, close the door, and wait. Do not start an oildrip yet.Wait until the kerosene is mostly burned away (about two minutes). Then open the door, assure thatflames are still present, and squirt in another shot of kerosene. Close the door and wait anotherminute.By now the burner should be hot enough to burn even difficult oil. So start a slow oil flow (2-3 d/s).The fire should be self-sustaining over the next five minutes. If so, you can walk away and let thefire heat up the stove. You should let the heater warm up on "low" for about 15-20 minutes.You should have a wood stove thermometer on the side of your heater at the level of the top of theburner. This will be the hottest location in the heater. 17
  18. 18. Wood stove thermometers can be obtained at any wood stove store and at most hardware stores.Most are round and use a bi-metallic coil to operate a needle that points to the temperature. Theyare cheap, typically costing less than $20.These thermometers usually are mounted with a magnet. However, an oil stove gets much hotterthan a wood stove and at high heat the magnet will lose its strength and the thermometer will falloff. So get one that has a hole in the middle that you can use to screw the thermometer to the heater.At the end of the warm-up period, the thermometer should show a temperature of at least 250degrees F (121 degrees C). I consider this "low" heat.After a successful warm-up period, you can then increase the oil flow to get it hotter. Keep in mindthat if you increase the oil flow too much, too suddenly, you will flood the burner and extinguish theflame.So increase the oil flow by no more than 100%. For example, if you have been running 3 d/s,increase to no more than 6 d/s.Let the heater run for another 15-20 minutes before increasing the oil flow again. If you doubled theoil flow, the temperature should be about double the previous temperature – probably around 500degrees or more (260 degrees C). I consider this "medium" heat.You can double the oil flow again. By now, you will probably see a thin, steady stream of oil ratherthan distinct drops. Again, wait 15-20 minutes. The temperature may climb to over 800 degrees(427 degrees C), which is hotter than you are likely to want or need.After another 15 minutes, you can increase the oil flow more. But you probably do not need moreheat and you will be pushing the limits of the heater as the temperature exceeds 1,000 degrees (538degrees C). At some high oil-flow rate you will "overfire" the heater.How will you know when you have overfired the heater? The heater will start to shake and vibrateviolently as smoke and soot start puffing out of the air tube and from around leaks in the door.What is happening is that you are burning more oil and producing more exhaust gas volume thanthe flue can extract from the heater. When this happens, exhaust gases develop pressure inside theheater.Remember that in normal operation, there is a slight vacuum inside the heater as the flue gases aretrying to pull air past the air tube restrictor. But now there is more pressure inside the heater thanoutside. So the exhaust gases start going up and out of the air tube.When the exhaust gases are going up the air tube, air cannot get into the heater to burn the oilvapors that are forming. So the fire starts to go out.As the fire dies down, the exhaust gas volume diminishes. As it does, the flue "catches up" andstarts to draw air back down the air tube.But keep in mind that during this period of time, although the fire has died down (due to lack ofair), the burner has continued to vaporize oil. As a result, there is now a large fog of unburned oil 18
  19. 19. vapors inside the heater. When the air comes back down the air tube, these vapors can now getoxygen and burn and are ignited by the small flame that is still present.You now get an explosion, just like the kerosene explosion I described previously. But because thedoor is closed, the blast of flame can only go back up the air tube rather violently.This once again causes the fire to die down, vapors to form, the flue catches up, the air comes backdown the air tube, and you get another explosion.These explosions are small (they dont blow up the heater) and occur several times per second. Butthey make the heater shake violently and belch smoke, soot, and fumes all over your room.I dont think that overfiring the heater is dangerous, although obviously it should be avoided. If leftunattended, the condition will self-correct as the violent pulsations inside the heater eventually putthe flame out.But you can stop the action immediately by simply covering the air tube with the restrictor plate(which will probably have been blown off the heater and is lying on the floor somewhere nearby).By covering the air inlet, you will prevent air from flowing back in to cause more explosions.But dont leave the air tube completely covered for more than a few seconds, or the fire will go out.Most likely, youd like to keep the fire going because its cold outside.So promptly open the restrictor plate a little. Just a 1/4-inch opening (6.35 mm) will be enough tokeep a little fire going until the oil flow gets back under control.Once you have stopped the violence by closing the restrictor plate, immediately shut off the oil.Within about 30 seconds, the excess oil in the burner will have vaporized and exited the flue. Youcan then open the restrictor to its normal position and turn the oil back on – but of course, to asomewhat lower oil-flow rate.Note that the burner will be extremely hot during an overfire condition, so the oil in it will vaporizevery quickly. Therefore do not wait long before turning the oil back on or you will lose your flame.If you do have a flame-out, remember that the burner is hot so you cannot put kerosene into theburner. You can, however, put oil in the burner. It will vaporize and smoke, but it wont explodebecause you are only letting in a few drops per second rather than a big load from a turkey baster.So open the oil valve and light the oil directly with a propane torch. It should ignite and you canclose the door and all will be back to normal.Of course, you will then need to open the doors and windows to get rid of the smoke and fumes.Youll probably have to sweep soot and ash up off the floor.Ive discussed the overfired condition in detail because sooner or later you will probably experienceit. You wont know how much oil you can feed your heater until you do. So just be calm, know thatit isnt dangerous, and go stop it.Note that the oil-flow threshold that causes overfiring is not constant. This is because soot in theflue will reduce the capacity of the flue. A badly clogged flue will result in overfiring even at just 19
  20. 20. moderate oil-flow rates. So any time your heater misbehaves, such as smoke coming out the air tubeat start-up, overfiring, or unexplained flame-outs, suspect a clogged flue.Flame-outsAn unexpected flame-out will result in oil filling up the burner and overflowing into the bottom ofyour heater. Because the heater shell will hold a couple of gallons of oil before it runs out the door,most of the time you will discover the problem before oil spills into your room – at least, I hope so.So what do you do about flame-outs? If there is just oil in the bottom of the heater, remove most ofit with a cup and then suck as much out as you can with the turkey baster. This will be a messbecause of the ash with which it is mixed. But do the best you can.You can then burn the remaining oil in the bottom of the heater. Before doing so, remove thealuminum burner.WARNING: Never start a fire under the aluminum burner. Doing so will melt it. The burner mustonly have fire on or above it.With the burner removed, you can light the oil in the bottom of the heater using a propane torch.Just heat one area. The ash will act like a wick and help keep it going. Once things get hot, the oilflame will be self-sustaining.You must be careful to avoid an excessively hot burn when so much oil is present. You will need touse the air restrictor plate to keep the temperature under control. Tend the heater at all times duringthis process and adjust the restrictor to keep the temperature below 600 degrees (316 degrees C).There will be more smoke than usual during this burn because much of the oil vapor formed willnot burn and will simply go up the flue as dense smoke. This burn may take an hour or moredepending on how much oil was left in the bottom of the heater. Once the fire has burned out, youcan reinstall the burner and return to normal operation.If you have spilled oil on the floor, you can get oil-absorbing "kitty litter" from any auto parts store.You sprinkle this stuff on the oil and sweep it around while it absorbs most of the oil. It will trap theoil so you can sweep it up and throw it away.I made this heater very simple for ease of building and operation. But this requires that you tend toit much like a wood stove. It is certainly easier to operate and tend than a wood stove, but youshould not leave it unattended for long periods unless you install some safety features (more on thislater).So what causes flame-outs? In my experience, they are usually caused by water in the oil. Youshould be using an oil filter/water-separator, but even so, you have to drain the water regularly. Ifthe water separator becomes full, water will get to your heater and put out the flame.Other causes include a flue that is clogged with soot, overfiring the heater when you are not presentto stop it, running too much oil into a cold burner at start-up, and failing to restrict the air tubeadequately. 20
  21. 21. ConstructionThe design of the heater is very crude, non-critical, and easy for most DIYers to build with commontools. You dont have to build a heater exactly like mine to make it work. You can feel free tochange most things to fit the materials you have available. For example, while my heater is madefrom a 40-gallon (150-liter) water heater tank, you could use a different size water heater, an oldpropane tank, a wood stove, or a piece of large steel pipe. You can make the door larger or smalleror in a different location. You can use many different things for the burners pedestal, etc.But there are a few rules that should be followed:1) Use a minimum of a 4-inch (10-cm) diameter air tube.2) Use a minimum of a 6-inch (15.2-cm) diameter flue.3) Use a burner of at least 5 inches (12.7 cm) in diameter.4) A larger/taller heater will be more efficient than a small one.5) The burner should be 5-7 inches (13-18 cm) below the bottom of the air tube.6) The air tube must be vertical for at least a foot (30 cm) above the burner.7) Use adequate air-flow restriction (usually at least 80% restriction).8) The flue must be a minimum of 9 feet (3 meters) tall.9) The oil line must run inside the air tube.10) The oil line should stop about 2 inches (5 cm) from the end of the air tube.Ill describe how I made my heater just to give you ideas and suggestions. But you can be ascreative as you like.I made my heater from a gas-fired, 40-gallon water heater (150 liters). I stripped all the coveringand insulation from it, removed the water pipe fittings, and welded the openings shut.Note that water heaters usually have a coating of glass on their interior to prevent the steel fromrusting. You may ignore the glass. It doesnt melt inside the heater and it appears to prevent anydeterioration of the steel. The interior of my heater looks the same as it did five years ago when Ifirst built it.I made my air pipe by using the 4-inch (10-cm) gas flue that wasalready present inside my water heater. Ill admit that cuttingthis pipe inside the heater, removing the bottom section, andwelding up the hole left in the bottom can be difficult unless youhave a well-stocked tool shop.So you may well find it more practical to take MENs adviceand use an electric water heater tank, which doesnt have a flue.You can then cut an opening in the center of the top for a 4-inchpipe that you can mount in the center of the tank, directly above Photo #17the burner, using MENs fabrication technique: Air tube and flue fittings on an MEN heater built by Journey to Forever First the holes on top of the tank are chalked, and then cut, using an electric saber saw (if you dont have one, MEN recommends that you rent one for a few hours). Cut the openings a little on the small side, and then spend a few minutes filing them out to size. The flue and air pipe are secured with bolts and 3/4-inch-wide angle iron tabs. 21
  22. 22. I cut some 1-1/2-inch steel strap (3.8 cm) and welded the ends together to make a collar for a 6-inchflue (15.2 cm) beside the air pipe. If you dont have the tools needed for this, use the techniqueshown for the MEN heater.The conical burner sits on a pedestal in the heater. No bolts orfasteners are needed or used. Photo #18 shows the pedestal, whichis made from water pipe and floor flanges. Photo #19 shows theconical burner sitting on top of the pedestal.I cut the door using a 3-inch (7.6 cm) cut-off wheel in a die grinder.If you use a very thin wheel, you can get a very narrow kerf.Cut the door about a foot square (30 cm) and remove it from theheater shell. You will need to line the inside edge of the dooropening with some sheet metal so that the door can close against it.A couple of cheap cabinet hinges can be used to hang the door anda simple clamp can be used to hold the door closed.The door does not have to be airtight or have a gasket to seal it. Butit is best if the fit is reasonably good. Photo #18The only problem with the conical burner design is building it. Theburner must be machined on a lathe because there is no commonhardware store item that is anything like it. I have a machine shop,so this presented no problem, but the average amateur builder willhave to have a machine shop make this part. I now machine theseand have them in stock for DIYers (see details at the end of thisarticle).The burner needs to be level as it is very shallow. You will eitherneed to put adjustable feet on your heater or use metal shims tolevel it.The heater size is not critical. But keep in mind that the heater willheat the air more efficiently if it has a large surface area. So asmall, squat heater may look nice, but it wont be efficient. Since Photo #19floor space is the major space issue, and height isnt, I used a small-diameter, but tall heater to get adequate surface area.Your stove should be painted flat black to maximize radiation efficiency. The high-temperaturepaint (1,200 degree F, 650 degrees C) used on wood stoves works well, although the oil heater canget so hot that it burns the paint off. Expect the paint to smoke a lot the first time you fire up theheater, so be prepared to ventilate your room.Please use a safe flue! It makes no sense to build a heater that uses free fuel and then have its flueburn your house down. Your roof opening should be lined with metal and a triple-wall, insulatedpipe should be run through it. If you are uncertain how all this is done, check with anyone whoinstalls wood stoves for guidance. 22
  23. 23. Burner design 23
  24. 24. The surface temperature of an oil heater can exceed 1,000 degrees (538 degrees C). So it is essentialthat you use safe installation practices. You should follow the safety guidelines for wood stoveinstallations.Specifically, this means that the heater must be at least 4 feet (1.5 meters) from any combustiblesurface. It must sit on a non-combustible surface like concrete, steel, or tile. The flue must beinsulated where it goes through the roof, and the rafters and other combustible surfaces in the roofmust be shielded by sheet metal.Burning vegetable oilAlthough I burn waste motor oil in my heater, I recognize that many readers will want to burn wastevegetable oil. So I did some experiments with my conical burner to see how it handled vegetableoil. I did not have any used vegetable oil, so all tests were done using new, generic, vegetable oilbought from the food store.First, it is obvious that vegetable oil doesnt burn as readily as motor oil. The burner must bebrought to a considerably higher temperature than needed with motor oil to initiate and sustaincombustion of pure vegetable oil. I was unable to obtain vegetable oil combustion using only asingle shot of kerosene as the starting fluid. But once started with a second shot of kerosene, veggieoil burned okay. A pool of liquid vegetable oil formed on the burner and the heater ran reliably andcleanly using only pure vegetable oil.I could even turn it down to a rather low setting without the heater "flaming out." The heater prefersto run a bit hotter with vegetable oil than what is needed with motor oil. However, it can be turneddown to a low enough setting with vegetable oil to still produce a reliable flame that is not too hot.At the opposite extreme, vegetable oil doesnt get the heater quite as hot as does motor oil. But itruns plenty hot enough.For ideal combustion, I found that vegetable oil needs a bit more air than does motor oil. I found itburned cleanest (virtually no smoke) with the air restrictor opened up from 2 inches to 2-1/2 inches(5 to 6.4 cm).Fuel consumption was quite reasonable. I found that at a low setting the heater consumed about 6ounces (0.18 liters) of vegetable oil per hour. At a moderate setting, fuel flow was about a quart perhour (0.95 liters).I didnt burn enough vegetable oil to get a really good feel for the type of ash produced, but afterburning the vegetable oil that I bought, I found that there was some soft ash that was all black(unlike motor oil "ash", which is light in color). But it was very easy to remove. So I think thatburning vegetable oil will make cleaning the heater quite easy.In summary, the heater will run quite well on vegetable oil. 24
  25. 25. Heater design 25
  26. 26. Automation optionsImproved starting systemWhile the heater is easy to start by squirting kerosene into the burner, this is not convenient orclean. Also, sometimes it doesnt produce enough heat to burn difficult fuels.Starting can be made easier and more reliable by installing a small tank (1-5 gallons, 3.8-19 liters)of starting fuel (kerosene or gasolene) above the heater. Connect this tank to a "T" in the oil linesuch that you can introduce starting fuel to the oil feed tube through a separate drip valve.Then when you want to start the heater, you simply start a flow of starting fluid through the valve ata brisk rate and light the burner. You can then turn on the oil at a low rate and let the two mix andflow into the burner.The starting fluid will guarantee that the oil will burn and the burner will heat up very quickly. Afterabout five minutes (depending on the type of oil you are using), you can turn off the starting fluidvalve and the heater will sustain oil combustion.If you have a fuel that is very difficult to burn (like synthetic oil or heavy gear oil), you can keep asmall flow (1 d/s) of starting fluid running at all times. This will ensure that the difficult fuel willkeep burning.Full automationThe heater design described above is simple, reliable, easy-to-use, and solves the problemsassociated with vaporization waste oil heaters. It uses no electricity, is quiet in operation, hasreliable oil flow, has a wide heat range, and is easy to clean and light. In other words, it is apractical design that you can use day in and day out for seriously heating your garage or workshopwithout costing you a lot of time and frustration.But many readers have expressed a desire to have a more automated heater that can do more (suchas heat their home) and requires less attention. The heater I actually use is self-cleaning and itoperates under thermostatic control. It has safety features so there is no possibility of an oil spill,and I only have to clean it once a month.Such a heater is much harder to build – beyond the ability of most DIYers – and it requireselectricity to operate. So the simple heater described above is best for most users. But due topopular demand, I am including the following discussion that describes how to build an automatedversion of the heater.This is a general discussion and will give many ideas for automating your heater. But because sucha heater requires custom fabrication, I will not provide any detailed plans because you will have tobe creative and develop your own automation systems.There are three issues to address for automation:1) Obtain automatic oil flow.2) Make the heater self-cleaning so you dont have to clean it every day.3) Safety features (automatic shut-off if there is a flame-out). 26
  27. 27. The drip system described above works very well with occasional monitoring, but the oil flow isunstable with temperature changes and therefore unsuitable for unattended operation. You eitherneed to make a temperature-controlled needle valve assembly or use oil pumps.An automatic, regulated, thermostatically controlled oil feed can be made to work withoutelectricity. I have not made a thermostatically controlled, gravity-fed drip system because I use oilpumps, but certainly one could be made.Conceptually, it is quite simple. A bi-metallic element (such as what is used in a thermostat) couldbe connected mechanically to either a needle valve or a disk valve such that as the temperatureincreased, the bi-metallic element would reduce the oil flow by either moving a tapered needle intoan orifice or by putting pressure on a flexible disk – and vice versa.The system would have an adjustment knob so that you could adjust the tension on the bi-metallicelement to control the temperature – similar to a typical thermostat.Im sure such a device could be built and that it would work beautifully. If you make one, pleasesend me the details.I use constant displacement oil pumps to obtain a constant and automatically controllable oil flow.Suitable pumps are difficult to find. While there are many chemical metering pumps available(check eBay), most pump too much volume, are incompatible with petroleum products, and haveshort life spans.There are two general types of positive displacement chemical pumps. One uses peristaltic motionwhere a flexible tube is squeezed along its length to push fluid through it. The tube fits inside acylinder and there are rollers on a wheel which is turned by a gear motor that pushes fluid throughthe tube as the wheel turns. I dont consider these suitable as the flexible tubing will fail ratherquickly with constant use.The other type is a diaphragm pump. These have a diaphragm that is operated by a crankshaft.There are check valves at the inlet and outlet to provide constant volume flow. By using a verysmall diaphragm motion, long-term reliability can be very good.Diaphragm pumps are normally driven by small gear motors. Such motors turn at high speed, usejournal bearings, and so have a life span of about 3,000 hours. Since the pumps will need to runmore or less constantly, they will be worn out in less than a single heating season.I use diaphragm pumps and replaced their gear motors with "Slo-Syn" motors. These motors haveso many poles that they operate at only 72 rpm, direct drive. They use double-sealed ball bearingsand will operate for millions of hours without attention.Adapting a Slo-Syn motor to a diaphragm pump usually requires a lathe. If you have access to one,I recommend making a Slo-Syn motorized diaphragm pump. You will need to change the "O" ringseals in the valves to handle petroleum. My pumps have worked for four years without failure.I use two pumps. This is because an oil heater cannot be automatically started easily like a propanefurnace can. 27
  28. 28. The first pump is used to keep the heater running continuously on "low" (about 7 ml/minute). Thesecond one is controlled by a common, programmable, wall thermostat to increase the oil flow (byan additional 10 ml/minute) when more heat is needed. This system works perfectly.To prevent any possibility of an oil spill during unattended operation (I leave my heater oncontinuously, including at night), I run the power to the pumps through a safety thermostatic switch.This switch is set at 120 degrees F (49 degrees C). If the temperature of the heater falls below that,such as during a flame-out, the switch opens and stops the pumps.Such switches are readily available for less than $20 from any wood stove store. They are used toswitch on blowers that are commonly used on wood stoves.As should be obvious, you will also need a small switch to bypass the safety switch when startingthe heater. Once it gets hot, the thermostatic safety switch will close and you can then open thebypass switch for safe operation.I could write a book on my experiences trying to build a self-cleaning burner. This has turned out tobe one of the most difficult and frustrating devices I have ever engineered and built. It has taken methree years of experimenting to get reliable operation.My system is quite simple. I rotate the burner under a sharp blade that scrapes off the ash as theburner rotates under it.The main problem with a self-cleaning burner is that I mistakenly expected it to be easy to scrapethe ash off the burner. I made this false assumption because the ash is very easy to remove when theburner is cold.But I have discovered that the main reason for this is that the aluminum burner contracts greatlywhen it cools off, and this breaks the hard ash off the burner so it virtually just falls off when youhold it in your hand to clean it.A second reason is that the ash that accumulates on the burner is very porous. This makes it easy toscrape it off the burner.But when the burner is hot and you keep scraping the ash off it, the ash neither breaks away fromthe burner nor becomes porous. As a result, the ash takes on the character of polished marble ratherthan loose, fluffy ash. So you have to make your cleaning system extremely rigid, strong, andpowerful.My early attempts at self-cleaning used a small gear motor and relatively weak scraping blades, andeither the motor would stall or the scraper broke. As I made the assemblies stronger, I found that analuminum burner would actually warp and droop and finally break apart. I also had constant bearingfailures as they could not withstand the heat and pressure inside the heater.Experience has shown that I need a powerful motor system, an extremely strong scraper blade, anash distribution system, a secondary scraper blade, a super-strong burner, external bearings, amassive drive shaft, and a pulse timer. Here are the details of my current system:Photo #20 shows my gear motor system. Im using a 1/4-horsepower motor (0.18 kW) driving a300:1 dual worm-gear box. The gearbox rotates at 6 rpm and can handle 20 horsepower (14.9 kW). 28
  29. 29. Because the burner support bearings have to withstandsevere radial loads and high heat, I never could get bearingsto hold up when they were inside the heater. The biggestproblem with such internal bearings is that the heat causestheir ball separators to lose their temper, distort, and eitherjam up the bearing or fall out, leaving the balls to move toone side of the bearing, where they fall out and the bearingcollapses.Also, due to the heat, the bearings cannot be sealed or Photo #20effectively shielded. So they must survive withoutlubrication and they must tolerate having foreign material getting into them.The solution is to keep the bearings outside the heater. This requires a long shaft to extend from thegearbox up inside the heater. This increases the loads on the bearings due to cantilevering, but thebearings can be very large, oil-cooled, and sealed. The ones in my current gearbox are taperedrollers and are completely submerged in an oil bath. They have been 100% reliable.The drive shaft is 1-1/2-inch in diameter (3.8 cm). It has a keyway to handle the torque.Photo #20 shows this motor/gearbox assembly welded to the bottom of my heater.When an aluminum burner is hot, it has poor strength, and the pressure of the scraping action of theblade is so high that it causes the burner to deform and sag. So the burner must be made of thicksteel.The primary scraper blade is made of tool steel that is 1/2-inch wide and 1 inch tall (1.3 x 2.5 cm).It takes this much strength to handle the load, even though the cantilevered end of the blade is only3 inches long (7.6 cm). Ive had lesser steel alloys and smaller blades just bend under the scrapingload.The blade must be very strongly attached to the heater so that it can scrape the burner withsufficient force. The blade holder is made as a three-piece steel assembly that triangulates the bladeto two points on the side of the heater, 90 degrees apart, and a third leg is welded to the bottom ofthe heater. This lower leg must be very strong as the blade is forced upward with tremendouspressure as it scrapes the burner. I have had 1/4-inch-thick (6.35 mm) steel snap from the tensileforce.Note that you cannot weld the scraper blade to its holder. Welding embrittles the blade and it willsnap off. I solved this problem by using a carbide drill to drill a pair of holes in the tool steel blade.The blade can then be mounted with grade 8 bolts to the triangulated holder.The primary scraper blade will accumulate ash just like the burner does. The ash will eventuallyspread out over the top of the burner forming an "umbrella." If such an umbrella forms, it will catchthe oil and direct it over the edge of the burner into the bottom of the heater. So this umbrella cannotbe allowed to form.To break up the ash on the primary scraper blade and prevent an umbrella from forming, I use asecondary scraper blade that is welded to the center of the burner. This blade can be relatively 29
  30. 30. small, but it still must be quite strong. I use a 3/8-inch-thick (1 cm) Allen key and it extends up andradially out over the primary scraper blade.As the burner rotates, the secondary blade scrapes the ash off the primary blade. For reasons I donot understand, the secondary scraper blade does NOT accumulate significant ash, so thankfully, itis not necessary to figure out a way to keep it clean. Note that neither of the scraper blades actuallycontacts the other blade or the burner.The blades can ride as much as 1/4-inch (6.35 mm) above the surface they need to keep clean andthey will still work. Amazingly, any gap between the surfaces will quickly fill with hard ash andproduce a new, hard surface that will require forceful scraping to clean. So the problem of highforces cannot be eliminated simply by putting space between the parts.It is also essential to use a sharp scraper blade and be sure to use plenty of relief behind the scrapingedge. Obviously, if debris can build up under the blade from insufficient relief, the cutting edgecannot contact the ash and the blade will be forced upward with so much force that failure isassured.Photo #21 shows the burner, scraper blades, and distrib-ution vane.I have found that the system works best if it does NOTrun continuously. It is better to let a small amount of ashbuild up and then scrape it off rather than scraping the ashcontinuously. By letting it build up, it is not as hard as thealmost polished ash that is produced by continualscraping. It also saves the cleaning parts if they are notactually used very much. Finally, the system is noisy, so itis best to run it infrequently. Photo #21To achieve this, I use an ordinary timer from a hardware store. Some of these have 12 or moresettings per day. I set my cleaning system to turn on every two hours and the cleaning cycle runs forjust two minutes each time.The ash that comes off the primary scraper blade quickly builds up in a heap under the blade. Youwill need to spread this around the inside of the heater or else you will have to clean it out everyfew days. To do this, I attached a steel vane to the drive shaft. This sticks out about 2 inches (5 cm)from the shaft and as the shaft rotates, the vane catches the pile of ash and distributes it around thecircumference of the heater.These systems make it possible for the heater to operate unattended for a month at a time whilekeeping my shop at a constant 70 degrees F (21 degrees C). Flame-outs are very rare, but if theyhappen there is no significant oil spilled. Perhaps an ounce of oil will overflow into the bottom ofthe heater before the pumps switch off, but I can ignore it and it will evaporate once the heater isback up to temperature.Hot water and home heatingWaste oil heaters can be used to heat water – either for domestic hot water or to heat your homeusing radiators. Safety is the problem. An oil heater gets very hot and can easily boil the water in a 30
  31. 31. water tank or in water-circulation pipes. Of course, boiling water produces steam, which can causean explosion. So it is absolutely essential to install "pop-off" safety valves that will vent the tankand/or tubing in case the pressure rises too high. These valves are always used in all water heatersso they are readily available at reasonable prices.You should also install a safety shut-off solenoid valve in your oil supply line. This should becontrolled by a thermostat in your water system so that the valve will automatically turn off the oilsupply to your burner if the water temperature exceeds a safe level – probably around 190 degrees F(88 degrees C). It should have a second thermostat to turn off the oil if you have a flame-out.Always assume the worst because Murphys Law assures it will happen. You remember Murphysbasic laws, dont you? Ill refresh your memory:1) Nothing is as easy as it looks.2) Everything takes longer than you think it will.3) If anything can go wrong – it will – at the most inconvenient time.Murphy has many other laws, but these give you an idea of what you are up against. All mechanicaldevices will eventually fail. So think about what will happen when something like your watercirculating pump fails and the water in the piping in your heater doesnt move while being exposedto the intensely hot flames inside the heater.Will your safety systems provide adequate control? If the pop-off valve opens, will water flood yourbasement? If the fire goes out unexpectedly, what happens to the oil flow? Does it soak your carpetswith black oil or contaminate ground water supplies? What happens to the system if you have apower outage?These safety issues are not trivial. Please deal with them competently and responsibly. Failure to doso could result in your injury or death – worse, how would you feel if one or more of your familymembers were injured or killed due to your negligence? What if you burn your house down?The biggest problem is how to control the heat when heating water – particularly when using arecirculating hot water heating system in your house. If you have too much fire, the water can boil.Too little doesnt give you enough heat.This is a serious problem when heating your home with hot water radiators as they need to be fedwater that is close to boiling to get adequate heat, but the water must never actually boil or you willget a steam explosion. So the temperature range is very narrow and you really need to have somesort of automatic regulation of the oil flow to hold a precise temperature.My heater is designed to work manually, like a wood stove, where you keep an eye on it and adjustthe temperature yourself. This works just fine for heating a shop or garage where precisetemperature control is not an issue, you are heating only air, which cant explode, you are present inthe room most of the time, and you dont heat it 24 hours per day. But the situation is different whenyou want to heat your home or water heater precisely and continuously.Therefore, I DO NOT RECOMMEND using this type of heater for heating water.If, despite my warnings, you insist on moving forward with your plan for hot water, I suggest thatyou wrap many feet of copper tubing in a spiral around the inside of the heater to act as a heat 31
  32. 32. exchanger. The flames from the heater will bathe these coils and will heat the water within them. Iwould use at least 3/4-inch tubing (2 cm), and larger is better.Use a safety pop-off valve at both the inlet and the outlet of this tubing. The heat will make thetubing weak and prone to sagging, so support it well.You need to be sure to pump water through the copper coil at all times that the heater is runninghard. This will keep the copper relatively cool and strong. If you run the heater hard with no waterin the tubing, the copper may melt.A water-only heater should be insulated on the outside to trap as much heat as possible inside theheater. You can use fiberglass insulation for this purpose as it will handle a lot of heat beforemelting and will not burn.For safety, I strongly advise that you place your hot-water oil heater outside so that only the pipesfrom it can reach inside your home. Use multiple pop-off valves where the pipes enter your home.Surround the heater in a strong structure so that if you have a steam explosion it will be contained.Wood stove conversionsMany readers wish to convert wood stoves to oil use. This should work well, although I have notbuilt one myself. Despite my requests, no readers have reported back to me to confirm their success.A wood stove is not as good as a round water heater because the flames will not uniformly heat itsinterior (assuming it is rectangular) and it is lower than a tall water heater tank. But it will looknicer than a water heater tank so may be acceptable in your home.You will need to completely block all air vents into the wood stove and install a vertical 4-inch airpipe (10 cm) – this is essential for proper operation of my heater design. If you wish to install thewood stove in your home, you will need to take some serious action to deal with the messiness ofan oil heater.This would include running the air pipe outside so that when you overfire the heater it wont belchsmoke and fumes into your house, but ejects them outside instead. You will then need to use adamper (a butterfly valve) since you wont be able to reach an external restrictor plate. You shouldmake the heater 100% airtight to prevent any smoke or soot from blowing out of leaks in the stove.Good luck cleaning the flue without getting some soot in your house. Frankly, I dont think an oilheater belongs in your home, but sometimes free heat makes us compromise.Probably a better way to heat your home with an oil heater is to place it somewhere where itsmessiness can be controlled. A good place might be found in the basement or outside in a small,enclosed, and well-insulated structure. You could then blow air over the heater and through ducts inthe house. Since most homes have forced-air heating, this should be relatively easy to do.To prevent ash and soot from blowing through the ducts and getting everywhere in the house, youshould install filters between the oil heater and the duct work leading to the house. You must also becareful to make the heater airtight so you dont get any odor in the house if you have an overfiredsituation. 32
  33. 33. Heating a greenhouseHundreds of these heaters have been built per my article at the Journey to Forever website. Manyhave been used in greenhouses.I designed the heater mainly for workshops and garages. It will work very well in a greenhouse, butyou will have to tend it. If you are willing and able to do so, you will be well-served by the heaterand save a lot of money on heating costs.You should think of a waste oil heater as being much like a wood stove. That means that it requiresfrequent attention, although not nearly as much as a wood stove. But you cant just set a thermostatand ignore it for months like you would most types of commercial heaters.It requires daily cleaning. It is very easy to clean, and can be cleaned in less than a minute, but youmust do so every day.It is not operated by a thermostat. You will occasionally need to check its operation and adjust theoil flow valve to get the heat output you want.The oil-flow rate will not be reliable. The flow will change based on the ambient temperaturebecause oil changes its viscosity dramatically with temperature. So for a given valve setting, the oilwill flow faster if the ambient temperature increases, and it will flow slower as the temperaturecools. You will need to adjust the valve every few hours to compensate for this if you have largetemperature changes between night and day.If you want to run it in a greenhouse where you only visit it once per day or so, you probably wouldlike to have an automatic heater control system.The heater I actually use is self-cleaning and it operates under thermostatic control. It has safetyfeatures so there is no possibility of an oil spill and I only have to clean it once a month. But such aheater is much harder to build – beyond the ability of most DIYers. For details, see "Fullautomation", above.I strongly suggest that you find a reliable source of waste oil before you build the heater. You willalso need some way to collect it as most waste oil is to be found in tanks and you will have to pumpthe oil into your container in some way.My heater is very thrifty on oil use. But it will still use about 3 gallons per day (11 liters). So if youuse it regularly, you will burn several hundred gallons per year. I burn about 500 gallons (1,892liters) per year up here in the Rocky Mountains where we have long winters. So oil collection issomething that will require your serious attention. Dont expect to take a 5-gallon gas can down toyour local auto repair shop and get oil.Like a wood stove, an oil stove produces smoke, soot, and ash. Therefore, its operation is somewhatdirty. You will need to clean the flue every 500 hours of operation. You can use a small gardenshovel to remove ash from the bottom of the stove every month or so. When I clean the burner, Ihave a pair of heavy rubber gloves that I keep in my ash bucket. I put these on to keep my handsclean when I handle the burner. 33
  34. 34. My heater will put out an awful lot of heat. My shop is poorly insulated, yet the heater has notrouble holding a room temperature of 100 degrees F (38 degrees C), when the outside temperatureis -20 degrees (-29 degrees C). Thats a 120-degree temperature gradient (67-degree C) in what isessentially a 4-car garage. Thats a lot of heat.But if you want more heat, it should be a simple matter to scale up the heater to a larger size. Themain limitation on heat is the flue. Youll need to increase the flue from 6 inches to 8 inches. Youllalso need a larger heater shell, a larger burner, a 6-inch air pipe, and a larger oil-flow valve.Alternatively, you could use two heaters.SourcesFor the convenience of my readers, I now manufacture machined, conical, aluminum burners andhave them in stock. They cost $50. Shipping adds $5 for US domestic or $15 for internationalorders.I also have precision needle valves in stock. They are also $50 each, but shipping is free if includedwith a burner. Shipping for a needle valve without a burner is $5.Photo #22 shows this valve. Orient it vertically so you canwatch the drops fall from the nozzle.I accept all forms of payment including check, money orders,major credit cards, and PayPal. If you wish to send a check ormoney order, my address is: Roger Sanders 12054 Deer Trail Road Conifer, CO 80433 USAIf you wish to use a credit card, Ill need its account number,expiration date and the cards billing address. If you wish to use Photo #22PayPal, send payment to my e-mail generally ship the day following receipt of payment by Priority Mail.Waste oil filters can be obtained from Dymatic, Inc., in Chicago. They have a suitable filter madeby Lenz, part number DH-1000-100. Their price is $49.95. I purchased my waste oil filter/water-separator on eBay. It is made by COMBU, model number 70101. It is a 100-micron filter using acleanable metal screen rather than a paper element. The Lenz filter also uses a metal screen. TheCOMBU filter is made in Italy, but there is an American dealer who carries them: COMBU Inc. 2001 S. 21st St. Parsons, KS 67357 USA 34