Now that I have my oil gun burning well, I’ve had more time to think over some theory. We are all burning relatively heavy oil in mostly siphon burners. Many of us have two problems: 1. A too long flame for the combustion chamber. 2. Some smoke or soot. With the existing boiler or furnace, it’s always a compromise between these two problems, because heavy oil needs time to burn completely. So the longer the flame, the more time for a total burn. My experience is: a very long, lazy, white flame burns clean; a short, crispy, orange (excessive air) flame not. Downsizing the nozzle helps, but there is a limit, because we want to have some BTU output. The existing combustion chambers are designed for a short HHO flame and our flames are always longer compared with an HHO flame at the same GPH output. Within some time we could be out of improving our oil guns and are stuck in this compromise. Improvement then, can only be found in (re-) building the furnace or boiler. Has anyone done this before?[

the flame length is something i’ve been fighting with. My boilers chamber is only 9.25” deep. There really isn’t anyway to make a siphon nozzle have a flame that short. I’ve built some great burners but they are always going to have some smoke because the flame is touching the refractory target on the back wall. It’s not cost effective for me to change the boiler since we only plan on being in this house for less than a year. I’ve got a great burner for my garage though.

Very true. That is why I have been doing a lot of research on blast tube and retention head design. Some success so far. Here in the US, almost all heating systems are way over sized (simple “rule of thumb” rather than true heat loss calculations) so underfiring us usually possible. Are the heating systems usually oversized in your country?

In the Netherlands 99 % of the homes are heated by nat gas. 0.9 % by propane. 0.1 % is me and some other lunatics who still heat with oldfasioned HHO. Most of us have boilers with very small combustion chambers. The boiler I use is a former commercial one with a big chamber. Hot air furnaces are not common in the Netherlands. Systems are not oversized in our country. We have only a few days a year some frost. In Belgium and Germany many homes are heated with HHO, but I don’t know about their sizes.