An oil furnace is a heating device that uses oil as its fuel source. There are several synonyms for this term, including oil-fired furnace, oil-burning furnace, and oil-powered furnace. These terms all describe the same type of heating system, which is commonly used in areas where natural gas or electricity are not available. An oil furnace is typically preferred by homeowners who want a reliable and efficient heating source, as well as those who live in colder climates where extreme temperatures are common. No matter what term is used to describe it, an oil furnace is an essential appliance for many households across the country.