Good evening All,
I have fabricated and have been successfully operating my scratch built waste oil boiler. I am getting things figured out, and it has been (fairly) reliably heating my house... better than my high efficiency furnace could. I have learned a lot through reading, and even more through trial and error. I follwed Tim C Cook's lead by using a cheap and effective dog bowl drip burner. When fed with a reasonable amount of oil, the boiler makes enough hot glycol to heat my house and detached two and half car garage to about 85 degrees Fahrenheit with ambient temperatures in the single digits. At this loading condition the boiler consumes about 10 gallons of waste oil per day. Given my cost for the oil (nothing), I find this rate to be acceptable.
I have two issues that I have not been able to resolve:
1) There is a good deal of soot produced by the boiler. This soot precipitates like snow and makes a real mess (our black and white cat is now black and dark grey). Is there an easy way to reduce or altogether eliminate the soot?
2) The soot seems to adhere to the flue by a process I can only describe as deposition. Every other day a few vigorous taps with a wooden stake are all that is required to dislodge the soot and send it out the top of the stack. Still, it would be better if I did not have to do manually clear the flue. I would assume that resolving issue number one would subsequently resolve issue number two.
Attached are two pictures of my device. Please keep in mind that I have access to some very heavy and precise fabrication equipment, and there are laser cut parts involved. As such, this is not likely something that can be done in a garage. Please feel free to ask any questions, and I will answer them as best I am able.
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Maybe someone can help me with the pictures... it doesn't seem to be cooperating with me.
A nozzle with low 5 psi air pressure will make it burn very clean with no soot, its a huge upgrade I made to my drip burner this year, see:
Siphon nozzle for WVO woodstove drip upgrade
Its what most of the commercial WMO burners use.
YVORMV - Your veg. oil results may vary, see www.burnveg.com/forum
95 Dodge Cummins 4x4
Zero fossil house- 100% solar power and heat.
Sun Wizard, I'm kind of concerned about using a gun type burner as most of my oil for heating is complete crap (wet, soapy, unknown constituents, etc...). Do you find that you need to do a lot of filtering and quality control to have a consistent burn? How does the lighting process go? I would likely leave the system running 24 hours a day as it is part of a hydronic system. Would this pose problems? Are you able to burn glycerin? The tertiary purpose of this stove is to dispose of glycerin, so it must handle it.
I can certain rebuild a boiler in a horizontal configuration if a gun type burner would work for me...
Thank you for the insight.
From my testing, a simple drip burner will always produce some smoke and soot, there is just not enough excess air to allow a clean burn. I can eliminate the smoke by adding a bit of forced air through the bottom of a somewhat more elaborate drip bowl with a surround to direct the air but there is still a bit of soot produced. I used to clean out the soot manually but now just dribble a bit of startup fuel into it and light it up, it produces very high heat for about a half hour and you have to stand by the stove and control both the flue and inlet dampers to keep the fire under control as the heat can easily melt through the thin flue pipe material. During these burnoffs the outer casing of my 100 pound propane tank stove easily reaches 700 deg even under control.
There is one fellow posting under the name "imakebiodiesel" in the "Military heaters on ebay" discussion that is using the $25.00 mil surplus tent heater insert to heat a hot water boiler for home heating, has been using it now for a couple winters (his current posts on that discussion are here) (mild winters, I think he is in Ireland). He starts on diesel or bio using the original, but somewhat modified, float control carbutetor til everything is up to temp, then he switches to an external grease drip. Seems to burn considerably cleaner than a simple bowl as the tent heater insert burner unit has several internal baffles and lots of air inlet openings, Don't think he ever said anything about soot but the burner still needs a bit of cleaning every few days.
You could modify a Becket type pressure burner to a syphen type plus all the extra heating and control but it would still need clean oil, or build Murphies version af a vertical babington burner, I suspect it would burn crap oil but would likely still need maintanance. His discussion is the very first sticky discussion at the top of this forum. It is somewhat elaborate but can make LOTS of heat on about any type waste oil. it uses a bit of compressed air through the nozzle as well as a pump for the oil supply and a fan for the excess combustion air. Murphy has plans available for it and I think some have used it to heat a boiler.
The huge heavy oil burning apartment building sized heating boilers use a burner similar to what Sun Wizard described above except they use dry steam rather than air, heats the oil as well as atomizing/oxidizing it. Smaller home built versions of these steam powered syphon nozzles are also used to fire the boilers on many hobby steam multi-passinger sized steam boats, a fair amount of info about them is available on the web.
Thank you for the words of enlightenment. I am quite familiar with the "burn off" that you have described. Since I built this boiler from scratch, I went rather heavy with the materials, relatively speaking. I used 10ga material throughout and have, on more than one occasion, managed to get the stove to produce a dull orange glow. I accidentally discovered the burn off technique when my fire went out and my drip bowl overflowed. I began scooping the sooty sludge out of the bottom of the boiler, but thought it might be interesting to just light the whole thing on fire. I was completely unaware of the necessity to regulate the incoming air. What resulted is what can only be described as the largest blowtorch I have ever seen.
But, a quick and violent thirty minute burn and the burn chamber looked like new. So, now I try to burn off the system once a week. It is a dirty affair to be sure, but does seem to keep things clean.
I do have the equipment to clean my oil, as I also make biodiesel. I think a siphon feed, low pressure air, gun type burner is order this summer. I would imagine that I will need to reconstruct my boiler in a horizontal arrangement.
So, does the gun type burner handle glycerine?
Thanks, again. You have been a fantastic help.
Early on I also had the fire go out and the bowl overflow. lukily I had a 3 gallon drip pan under the stove and I cought the problem before the pan overflowed. The flamout was caused by high winds and is the reason I added the optical flame sensor, it turns off the feed pump if it does not see a flame, saved a lot of cleanup. I also added a barometric damper to the chimney and that pretty much eliminated the wind blowout problem, maybe had it happen once since then.
Burnoff - Yep, pretty dramatic - I should have stated that the stove casing needs to be pretty air tight to be able to control the burn with the dampers, if there are too many air leaks in the stove you may not be able to choke off enough air using the dampers to keep the burn under control.
CKburners.com is a website selling specialty produced parts for Beckett style syphon burner mods to allow burning either veg or used motor oil, they sell a nice machined aluminum block heated syphon nozzle assembly. They are the only place I have found where you can buy most of the critical parts needed for the conversion from the same place without haveing to cobble together heaters, nozzles, nozzle holders etc. from other sources (they sell there kits on ebay also but they are a bit cheaper from the website). Prices are acceptable and comperable with other vendors, what they don't sell directly they have links for. I bought one of there heated syphon nozzle block kits and ordered a Kagi SS blast tube air baffle, plus verious solenoid valves etc for the mod but I have yet to get back to the project, I just don't need that much heat for my small 800 sq ft house. The Beckett burner will eventually heat a friends 4000 sq ft high-bay shop.
The website has lots of straight info on what works well for the Beckett conversion. The info is good and condensed mainly from there own testing and the thousands of posts on the Yahoo groups altfuelfurnace discussion group.
This links to my "3rd heater" discussion with lots of drip heater info and details of my fuel feed pump mods (scattered throughout) as well as the schematic for the optical flame safty.
Burning glycerin - Everything I read says NO, some say they can mix a bit of glycerin with biodiesel and get it to burn but they usually also say they have to clean or replace nozzles a lot due to clogging (my experiance is that pressure nozzles really can not be cleaned reliably, not many times anyway, replacements are a few bucks but it adds up). The only burner I have read about that will burn glycerin is actually sold as an "incinerator" it seems to actually be a standard Beckett fuel oil fueled pressure burner that has had a second syphon or pressure nozzle added to it, the standard burner creats a full hot flame and the secondary nozzle injects a mist of glycerin into this flame, due to the high heat the glycerin burns fine and produces added heat, they also say it works with waste antifreeze. I don't rememember the product name but a web search for "incinerator burner" or similar should find it.
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