I have just found this site, and I'm pleased to find that I'm not on my own wanting to burn waste oil.
I built a heater five years ago just to prove a point after a discussion with some friends on the viability of just such a project. I might add that I was howled down when I suggested that it should be possible, so, being a "pig headed" old coot proceeded to prove my point.
My heater works on the dripper principle with a two stage burn, to evaporate the oil at a low temperature, the idea being to trap as many of the volatile heavy metals as possible in the ash, then burn the resulting rich gas mix in a secondary airflow.
To cut a lomg story short, it worked pretty well right from the first burn but required a little fine tuning to adjust the secondary airflow.
There is a photo of the prototype on my web pages at: http://members.ozemail.com.au/~ekips/
Yeah,... I know, Why haven't I got a recent photo? The truth is that I've been too lazy to update my web pages for some time, but if enough interest is shown I will post a more recent picture.
Because of our relatively mild winters here in South Australia I have adjusted it to produce about 150,000 btu Max. When I first installed it in the house to test it, it nearly drove us outside on a cold wintry night and was only bought under control by cutting off the oil and lifting the manhole into the ceiling space to get rid of the heat as it continued to burn for about twenty minutes after the oil was cut off. (It did melt the TV aerial cable which was about 4 feet away though).
I have a 500 gallon tank in an old horse stable about 40 yards from the house and the oil is piped to the heater through a buried 3/4" polypropylene pipe, with the exception of the section inside of the house which is 1/2" copper with all brazed joints to avoid the possibility of leakage.
Shirl, my long suffering wife was horrified when I suggested bringing it into the living room, but I pacified her with the story that it was only for a test run and that the slow combustion heater would be going back. One thing led to another and 5 years later it is still in place, gradually Shirl has learnt that there are better things to do with your spare time than cut and carry wood and clean up sawdust, chips and ash from the living room carpet. I think that the final barrier came down when the local Mayor called in it have a look and was so impressed that he went home and built one for his workshop.
It also helps to be on good terms with your local trucking company, as many of the parts can be salvaged out of his junk heap. The body of my heater is made from two worn out truck brake drums.
Don't give up, it can be done, and it's not that expensive if you have a reasonable workshop and a few tools.