What type of oil is typically used in residential heating systems?

Light fuel oil is the correct choice for residential heating systems because it is specifically refined for use in heating applications. This type of oil, often referred to as No. 2 fuel oil, has properties that make it ideal for combustion in oil burners, resulting in efficient and consistent heating. It has a lower viscosity than heavier oils, allowing it to flow easily through the fuel delivery system and be properly atomized for combustion.

In contrast, vegetable oil is not suitable due to its composition and properties, which are not designed for efficient combustion in heating appliances. Heavy crude oil contains larger molecules and impurities that make it a poor choice for fuel oil applications, as it can lead to inefficient burning and increased emissions. Diesel fuel, while similar to light fuel oil, is not typically used in residential heating systems because it is formulated differently and often has additives for automotive use, making it less optimal for residential heating.