I ordered a nozzle (0.5gph) adaptor, and thermal snap switches from Jessie and installed them on an old burner I had lying around although I don’t know who makes it. I am good at building and figuring stuff out, but new to oil burners so I am not sure how to compare my results. I also made my own Kagi style retention head but I only had pictures to go off of (from a stainless steel candy dish I bought at Wal-Mart). I made the preheater similar to others design, although I only have a single 300 watt band heater.

I set up my modified burner on the sidewalk and turned it on, it sucked the oil through and fired up. The first time I ran it I did not have a solenoid on the air or oil, but just turned them on and off by hand for testing. I did get a flame at first although it was a lot smaller than I was expecting. I was surprised by one thing as well, which I am not sure if it is normal or not, the spark stayed on the whole time, is this normal? When I turned off the burner, I still had the air and oil on, so the flame stayed, I think I actually got a better flame without the fan on. I know the CDS cell saw something because it would not turn the fan and spark on again until I turned off the air and the flame went out.

I have since installed solenoids on the air and oil before the pre heater, I have another problem, when the unit is off, the nozzle drips. Is the solution to this to install a solenoid after the heater? And if so I saw others having problems with the seals being destroyed by the heat, has anyone solved this?

By chance I tried another experiment, when I was done and packing up, I wanted to get the rest of the oil out of the line, so I figured I would burn it, I decided to blow into the oil line to see what would happen. When I did this the flame got considerably larger although I didn’t take a picture of that.

The last problem is that I am not sure if I am getting complete combustion, I think some of the oil mist is not being burned, as well the flame had some smoke to it, although I am not sure what is normal. I tried adjusting the pressure up and down between 5psi to 20, it didn’t seem to help much, although it did change the flame size, although it never got bigger than what was in the picture. In general any help or suggestions on tuning up this set up would be appreciated.

Lastly for reference, the boiler I am planning on putting this into is a Weil-McLain 68V size 468V with a chamber size of 15.5 Height X 14.125 Width, X 12.5 Depth. I hope this is adequate as I bought this boiler just for this use. My home currently has a gas boiler so I am not worried about back up heat if this fails. The boiler came with a Riello burner but I haven’t modified it as my home must of at one time (before I bought it) had oil heat, since I have 2 tanks (275 above ground) in my basement which have about 400 gallons of HHO in them that I want to burn as well.

Great looking setup. Good job on the turbine difffusor as well, and yes, the transformer is on all the time. You do get quite a good flame when the burner is out of the combustion chamber, but it’s misleading, it’s an entirely different animal when the burner goes in so you do need that fan on.

I haven’t heard anyone mention putting a high-temp solenoid after the preheater and the dripping can be eliminated by using a ballpoint pen spring and a 4mm ball bearing in the siphon nozzle.

The hotter the oil the better the combustion; your oil is probably just not hot enough so you’re getting some overspray of cold, non-combustable oil feathering out on the sidewalk, in a hot chamber, more of it would burn away. Are you preheating the air as well?

The 4 mm ball works great as a flow restrictor in a Delavan SNA .5 GPH nozzle. I don’t know about Hago or other sizes. An other size of ball may be used.

Thanks for the suggestions. Last night I got a ball and a spring from a ballpoint pen and put them in the nozzle. After doing this no oil comes through the nozzle via the nozzle’s own venturi suction action. I have seen many posts on using a constant level device, and also on using a pump and regulator to feed the oil. I am a little confused on if you need some low pressure pump 1-4 psi to feed the nozzle, or if the constant level device provides this. I would think you need a little pressure to get the ball/spring in the nozzle to open (although I will play with the spring tension and see if that helps). I also posted some pictures last night of my burner firing while I was blowing into the oil line to put the oil under a little pressure (this was without the ball/spring since I couldn’t get it to open with my lung pressure).

There is also a picture with a smaller flame from just the venturi suction, I am not sure which one you looked at. I do preheat the air and oil via the preheater design that is posted on here, although I used a short section of ¾” threaded steel pipe and adaptors to go back to copper since the band heater fit very snugly around it. Some of the spray on the sidewalk was from when I was purging the air out, my heater isn’t insulated and it was cold out so I can also imagine more would burn in a chamber. Anyhow my main question now is do I need to pressure feed the oil, or will a constant level device work, and if so what height above the nozzle should it be. I did lift my oil supply up a few feet, but it didn’t seem to affect the flame size.

A continuous spark (or not) depends on the type of controller you have on your burner. Just be sure it doesn’t jump to the nozzle or head. To deal with afterdrip you could place the oil solenoid between heater and nozzle, but the solenoid will not like that. Place it before the heater and get some kind of afterpurge of atomising air. The afterpurge cleans the nozzle, burning the oil that would drip. A clean nozzle is also nice on startup: the flame starts small instead of a big boost with the first second of unburned oil mist. Two ways to get afterpurge:

1.In case of small compressor that runs at the same time as the blower: no air solenoid is needed. Use either a time relais to get the compressor running a few seconds longer than the burner or fit a small air tank in the air line. The tank empties itself after shutdown thru the nozzle.

2. In case of an independent air source (big compressor): put the time relais on the air solenoid.

The large flame you had when you purged the oil line was because you were feeding the nozzle with a lot of oil. You will need to find out the right settings on air and oil to get the right flame. Try out all possible combinations. First outside. Start with the blower vanes (almost) closed. Lots of air will give a beautiful short, roaring blowtorch, but cooles the flame and gives less BTU output. Read Coen’s bible on flame characteristics in the files section.

When you’re testing outside, it is normal to have some unburned oil mist and smoke. Even HHO smokes. Attach it to your boiler and it will be less or hopefully gone.

You have a wide but short combustion chamber. I see the retention head you made is conical. Try the head reversed on the blast tube. It will widen the flame. The trouble however with shortening the flame in whatever way is that it is difficult to get it “naturally” burning (my opinion; Ron Schroeder will not agree on this). It’s someway forced to burn not the way it wants. Heavy oil seems to need time to burn completely. In this case time is a long flame… If your boiler is old enough to experiment with it and you have a large door to the combustion chamber it could be wise to extend the chamber, to allow the burner a long flame.


I am not really in disagreement with you here but if the “natural” flame is as long or longer than the combustion chamber, it won’t burn completely either. Burn time is mostly related to mean particle size of atomization. (and partially combustion air temperature) Flame length is [burn time] X [air_fuel velocity] so either atomizing to a smaller particle size or slowing down the air by making the air stream bigger around (with the same volume) will shorten the flame. Swirl will also give a longer particle travel distance for a given distance from the nozzle. The difficulty is to get enough turbulence but not too much turbulence to get good mixing between the air stream and the oil mist.