In Greece the heating oil went up to 1.20 Euros. Meaning that is WAY too expensive to burn. Therefore, I look for alternatives and the used olive/vegetable oil from local souvlaki/gyro store seems more appealing as alternative fuel.

But what modifications needed in order to use filtered used cooking oil to my central's heating burner? Usually the most common fuel for central heating is the red diesel, but that priced over 1 euro made it too expensive.

Central Heating in Greece use diesel to heat water and that is circulated to heating elements where heat is emitted.

Of course prior to use I'll filter it using cloth and possible stoned and sand before filling my diesel tank with used cooking oil. Also, filtering oil is cheaper than making it into biodiesel (requires no heat).

1 Answer 1


What you're looking for is "making biodiesel".

This is a process called transesterification which converts the longer carbon chain molecules in the grease into shorter chain molecules. That will give it the liquidity and flow of diesel, and will largely work correctly in burners made for diesel.

How to do this is far too broad for an answer here. What I can tell you is there's a large community of people doing exactly this. Mostly for automobile conversions, but most of this will apply to you. Thousands of Youtube videos, blogs, whole forum sites dedicated to the topic.

Or, modify the furnace for the fuel.

Waste vegetable oil generally has 4 essential flaws that make it unfit for use for diesel.

  • it is too viscous (solved by transesterification or heating)
  • it has particulate matter in it which will clog injectors. (Solved by filtering)
  • it has acidity which would corrode fuel handling equipment i.e. pumps and injectors (solved by titration, which is done as part of the biodiesel making process)
  • it has undesirable water content. (Solved by drying, also part of the biodiesel making process).

So you can adapt machinery to deal with each of these problems, instead of making biodiesel.

This is done in cars by modifying the car for SVO or WVO. Largely by providing heating of the SVO/WVO tanks, and switching tanks to real diesel during engine warm-up and near shutdown (so there is real diesel in the fuel injection system next time you start up).


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