Heating oil, or
oil heat, is a low
viscosity,
flammable liquid
petroleum product used as a fuel for
furnaces or
boilers in buildings. Home heating oil is often abbreviated as
HHO[1]
Heating oil is commonly delivered by
tank truck to residential, commercial and
municipal buildings and stored in above-ground storage tanks ("ASTs") located in the basements, garages, or outside adjacent to the building. It is sometimes stored in underground storage tanks (or "USTs") but less often than ASTs. ASTs are used for smaller installations due to the lower cost factor. Heating oil is less commonly used as an industrial fuel or for power generation.
Red dyes are usually added, resulting in its "red diesel" name in countries like the
United Kingdom.
Solvent Yellow 124 is added as a "Euromarker" since 2002 in
European Union.
Heating oil is very similar to diesel fuel, and both are classified as
distillates. It consists of a mixture of
petroleum-derived
hydrocarbons in the 14- to 20-carbon atom range. During
oil distillation, it condenses at between 250 and 350 °C (482 and 662 °F). Heating oil condenses at a lower temperature than the heavy (C20+) hydrocarbons such as
petroleum jelly,
bitumen,
candle wax, and
lubricating oil, which condense between 340–400 °C (644–752 °F). But it condenses at a higher temperature than
kerosene, which condenses between 160–250 °C (320–482 °F).
Heating oil produces 138,500 British thermal units (146,100 kJ) per US gallon and weighs 7.2 pounds per US gallon (0.85 kg/l),
[2] which is about the same heat per unit mass as the somewhat less dense diesel fuel.
Number 2 fuel oil has a
flash point of 52 °C (126 °F).
Leaks from tanks and piping are an
environmental concern. Various federal and state regulations are in place regarding the proper transportation, storage and burning of heating oil, which is classified as a
hazardous material (HazMat) by federal regulators.
Heating oil may be blended with
biodiesel to create a product that burns similarly