What are the pros and cons of the siphon nozzle design over the pressurized waste oil nozzle design? It appears also that the oil must be heated to a much higher temperature with the siphon design, is this true? Also, how long does it take for a preheat using the band type heaters?

I think you are confused: the siphon nozzle IS the pressurized waste oil nozzle. Depending on the temperature of the room, the pre-heater should only take a matter of minutes to get up to the required temperature. I’d say under 10 minutes, but you just leave the band heaters on all the time, and if the pre-heater is insulated real well, the energy use is nominal.

I thought both types of nozzles were used with WVO, but the siphon was preferred by most who tried both. Are you saying you are putting pressurized oil through the siphon nozzle? The design of the siphon nozzle uses pressurized air flowing past a venturi where it creates a vacuum that sucks the oil from a constant level reservoir, which would typically be slightly lower than the nozzle. So that begs the question of those who have their resevoir higher than the nozzle, How do you stop the oil from continuing to flow after the burner is shut off?

Do you use a solenoid valve between the resevoir and the nozzle? Or, during burner shutdown, do you shut off the supply to the resevoir and let the level drop to below the output tube and let the tube drain through the nozzle? There have been comments that people have had better performance with the resevoir higher than the nozzle, but what makes it better? My guess is that by using a solenoid valve, the tube between the resevoir and the valve would be full and ready to go whereas with the resevoir lower than the nozzle and without some sort of check valve or solenoid valve, the tube would drain back to the resevoir upon shutoff and there would be a slight delay to fill it when starting the burner.

OK, now I know where you headed. Yes, I built two different oil burners, a standard nozzle and a siphon nozzle. The standard nozzle model uses the same oil pump on the side. I preheat the oil between 110-120 degrees F (43-48 Celsius)before it gets to the oil pump using cartridge heaters in an aluminum brick attached to the face of the oil pump. Preheats the oil pump as well. The oil pump high-pressure side pushes the hot oil down the nozzle tube that has three 1” brass collars on it with band heaters on those. That brings the oil up to 375 degrees. (190 Celsius) There are problems: specifically one of the nozzle and the Kagi air diffusor gunking up on the end at the nozzle tube itself.

It must be cleaned at least once every two weeks. That’s the longest I’ve gone, others may have gone longer. I think the burn is better and much quieter on a standard nozzle oil burner. The analogy would be that of a looser, blossoming flame that billows out into the chamber as opposed to a blow torch, where the flame is fast, concentrated and tight. The maintenance is better on a siphon nozzle setup. Eric is at the two month mark which is a goal I think is acceptable considering these home-built units are only similar in concept with the larger, commercial units. We have members that are or are attempting to set up their burner for pottery kilns. A full-attended use as opposed to a residential furnace where the temperature is controlled by the thermostat. So, if you are heating a kiln then a manual valve could be used as a shut-off, instead of a solenoid (using the gravity principle).