The beginnings of a waste oil fired foundry
Ronald E. Thompson
Copyright 2007, all rights reserved

Gun style burners look complicated at first blush, but they are relatively simple when broken down into the systems. A lot of the gear on one of these is for safety in unattended operation and can be dispensed with, greatly simplifying their use on a furnace.

A picture might help you visualize what I am trying to convey: 

The gun burner consists of a blower, a fuel pump feeding fuel to a nozzle at about 100 PSI, and a transformer that energizes a pair of electrodes to ensure combustion with a large, nasty spark. The nozzle and spark electrodes are contained in an air tube that directs the blown air across the nozzle and the resultant fog of fuel, which is lit by the constant spark, resulting in a very hot, white flame.

The whole thing can be run on a 120VAC extension cord.

So far I have learned that it is possible to burn alternate fuels in a gun type burner intended to burn home heating oil (HHO). To burn heavier fuels, such as waste vegetable oil (WVO) or waste motor oil (WMO) you need to change to a siphon nozzle and heat the incoming fuel. The siphon nozzle requires a small amount of compressed air to operate and requires a filter, such as an automotive oil filter. The original nozzles that come with these burners require a finer filter of 10 microns or better. It is possible to use the original nozzles for the heavier fuels, but everyone who has reported trying it gave up due to clogging problems causing too frequent disassembly, cleaning and/or replacement of the nozzles.

The yahoo group ( has pictures and files showing several iterations of homemade oil heaters. Most use band heaters or cartridge heaters and a thermostat of some sort. The ideal temperature range is 150 to 160 degrees F. Any hotter, while improving the burn, will cause problems with coking of the fuels and the resulting solids clogging the nozzle prematurely.

The 'go to' source seems to be Patriot supply (
They have a search function on their site that is useful.

The siphon nozzles are about $20US and they require an adapter that is about $17US (as of this writing, February, 2007).

As I said, they also require a small amount of compressed air. Patriots web site has specs that show a need for around 5 PSI and about 1 CFM of air flow (depending on the nozzle chosen).

Siphon nozzles can be had as low as .2 gallons per hour (GPH) up to 1 GPH, as shown on Patriots web site. Other sizes may be available from other sources.

I should also mention that gun burners are not the only game in town. It is possible to atomize the oil in other ways than with a nozzle that requires fine filtration.

I recently purchased a book from Colin Peck at
It is a spring bound book that talks about building an oil fired furnace. He uses a vacuum cleaner motor as his original blower, but ends up making his own. He also made a coarse oil flow valve with no small passages to clog easily. It is a workable design that accomplishes quite a lot, but the book is pricey. Since it is from the UK, I had to exchange US Dollars for Pounds and pay overseas shipping, all told around $40US.

I also have an excellent book from Steve Chastain titled Build an Oil Fired Tilting Furnace. It is available directly from Steve at
Steve uses a large homemade blower and a venturi to atomize the oil. Kind of like an over-sized carburetor for a lawn mower. Again there are no small holes to clog. At half the price of the former book, Steve's book is worth the price just for the burner info. Steve also has other worthwhile books for sale on his site.

Both of these, however, are large furnaces, burning several gallons of oil per hour. I am of the opinion that for a smaller furnace, the gun burners offer more to the hobbyist. And if you are willing to buy the fuel, they can run 'out of the box'. It is in trying to operate them on free fuel that the mods are needed.

All of these are capable of iron melting temperatures, but in the case of Steve's design, it it strictly for aluminum due to the built in steel crucible.